Dr. Tommy Wood

There's a much more recent study that took again older adults and randomized them across three different groups. One was like a low intensity group. Another group basically did kind of zone two type work on a treadmill three times a week. And the third group did a high intensity interval training intervention, which is the Norwegian 4x4 protocol. So four minutes 85 to 95% of maximum heart rate. They had a three minute rest in their protocol. They did that four times over.

Dr. Andrew Huberman

That was three times a week.

Dr. Tommy Wood

Three times a week for six months. That's, that's pretty intense. But what they showed was that that high intensity interval training group, they improved their fitness just as well as the Zone 2 group, interestingly, but they had much better improvements in hippocampal function and maintenance of hippocampal structure on an MRI scan. And they maintained that benefit for five years after the six month intervention. So they worked really hard for six months, but that that benefit was maintained for, for a really long period of time.

Dr. Andrew Huberman

Welcome to the Huberman Lab podcast where we discuss science and science for everyday life.

Podcast Narrator

I'm Andrew Huberman and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. My guest today is Dr. Tommy Wood. Dr. Tommy Wood is a medical doctor and neuroscience researcher at the University of Washington in Seattle. He is also the Chief Science Officer of Better Brain, a company that provides free brain health coaching. Tommy is an expert in neuroplasticity and human performance and how science based protocols can be used to improve your focus, ability to learn and skill expression. His work applies to everyone from the novice to the elite expert and for all kinds of skills, cognitive language skills, athletic and creative endeavors. Today we discuss the brain states that favor learning and importantly how to get yourself into those states. We also discuss how to get the most from a learning session, for instance, how long that session should last, how many sessions to do per day, and perhaps most importantly, how to tune your mind and body to get better at learning. That's something we don't often hear in the context of learning. A neuroplasticity that our brain circuits for focusing and learning are also capable of plasticity, meaning you can literally get better at getting better. Today we discuss things like flow states and something called a clutch state, which is a seldom mentioned but critical brain state to accelerate learning and performance. In fact, a clutch state is the state that you want to seek to learn and perform at your best. We also discuss how different types of physical exercise, from long slow cardio to brief high intensity cardio and different forms of resistance training each open the window for distinct types of neuroplasticity and learning. So this goes way beyond the general discussion about exercise improving your brain. We get really granular about exactly what types of things to do to improve your brain in specific ways. As a career neuroscientist who has worked on and taught neuroplasticity for decades now, it's rare that I encounter someone with as deep knowledge about the real science and application of learning and plasticity as Tommy has. He's also extremely unique because he has a ton of knowledge about new science based protocols for plasticity and he's also an athlete. We discussed that a little bit at

Dr. Andrew Huberman

the end as well.

Podcast Narrator

So today you will hear a lot of information that I am confident you have not heard on this podcast or anywhere else, frankly, about exercise, mental training, nutrition and supplementation, and much more. And how you can leverage each alone and in combination to learn new skills with accelerated speed, precision and durability over time. I should also mention that Tommy recently released a new book that he wrote entitled the Stimulated Future. Proof your brain from dementia and stay sharp at any age. It's an excellent book. If you're interested in following up on today's discussion and learning more about how you can make your brain better at any age. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public. In keeping with that theme, today's episode does include sponsors. And now for my discussion with Dr. Tommy Wood.

Dr. Andrew Huberman

Dr. Tommy Wood, welcome.

Dr. Tommy Wood

So amazing to be here. Thanks so much for having me.

Dr. Andrew Huberman

This is my favorite topic in the entire world. What is more interesting than neuroplasticity? Right. The brain is so interesting, but its most interesting feature, in my opinion anyway, is that it can change itself.

Dr. Tommy Wood

Essentially, that's its core, most important function. If it can't do that, literally none of the other functions matter, you could argue. And it's something that we have to be able to do right until the end of our end of our lives.

Dr. Andrew Huberman

You have an eclectic research tapestry today. We're going to talk about neuroplasticity. What it is, what it isn't, how to access it for men, for women, different ages. And you also are a high performance coach. You're also a competing natural strongman. Yeah.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Does that mean lifetime? No. No gear.

Dr. Tommy Wood

Lifetime. Well, it's tested. I. Yeah, Lifetime. No gear for me personally, but it's a drug tested version of the strongman sport. So yeah, if you, if you compete in natural strongman, then you, you get tested.

Dr. Andrew Huberman

Great. So we'll, we'll talk about that.

Podcast Narrator

I'll resist the temptation to talk about

Dr. Andrew Huberman

your two boxer pups because I'm a dog lover. That's a different episode. Neuroplasticity, I know what it means to me. How do you conceptualize it? How do you think people should think about it in terms of wanting to learn things and not forget things?

Dr. Tommy Wood

I essentially just think of it as the brain responding to inputs in order for us to then be able to better navigate and survive our environment. And that's why I think it's such a fundamental part of what the brain does. And essentially every time you learn something, interact with something, remember something. The principles of neuroplasticity are engaged, right? You are making new synapses or strengthening synapses, weakening other synapses. A lot of people don't realize that, particularly brain development. But then also the refining of functions in the brain through neuroplasticity includes the pruning or removal of synapses. Often we think about, it's all about growth and new connections, but actually it also involves the refining or removal of other connections that aren't needed. That's a massive part of brain development in the first place. And this is a process that's essentially continuously ongoing. And you can think of it as its primary role is so that you can navigate, survive the world around you. And that's through learning skills, through remembering people and things. In fact, and where I. One of the. One of the things that's most interesting to me about neuroplasticity and the way we think about our brains over time is that I think people have conflated neurogenesis and neuroplasticity. So when we're thinking about brain development, we're thinking about then also brain function with age and either cognitive decline or maintaining cognitive function. We thought that the adult brain was fixed, or then it was fixed and then it lost function. And this goes all the way back to Cajal, who said the adult brain is immutable. He told us that you got into adulthood, it finished developing and then it was kind of done. He then at other times also said that changes in the connections between neurons could explain learning. And so there he's talking about neuroplasticity. But we kind of got this idea that the brain was essentially fixed as an adult and then couldn't change anymore. But that can't be true because you still learn and remember things on a daily basis as an adult. One of the things that I think we've gotten confused about is the fact that the adult brain does not make new neurons in many places, maybe in olfactory bulbs, in the dentate, gyrus, the hippocampus.

Dr. Andrew Huberman

Tiny. Tiny.

Dr. Tommy Wood

Yeah. But compared to the rest of the brain, you're not really making new cells. And so because of that, we thought, well, we can't then grow and adapt or change our brains as adults. But just because we have a fixed number, relatively fixed number of cells, doesn't mean that we can't change the connections between those cells. And that's happening all the time. And that is the main principle of neuroplasticity.

Dr. Andrew Huberman

Yeah, I like your definition, in part because I agree with it, in part because it encapsulates a lot of things, including helping to clear up this misconception that we generate new neurons. I think the attractiveness of the new neuron idea is just. It's so sticky. And so we would all love to believe that.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

But maybe there's good reason why we don't add new neurons. Maybe. Maybe it's not adaptive. Right. Adding new elements to a circuit is maybe not the best way to change a brain circuit. I think people also like the idea that, you know, every organ in our body turns over its cells, that we're not the same person, literally that we were. The brain is same cells you're born with, minus a bunch of them that die off, as you pointed out. And thank you for mentioning pruning and the removal of connections as a fundamental aspect of plasticity. In terms of motor skill learning. Let's say I decide I'm going to practice billiards and I'm okay now, hang in there. But let's say I want to get really good as I learn and get better and better. Can we reliably say that most of my improvement is the removal of inappropriate action and therefore synaptic connections?

Dr. Tommy Wood

I don't know whether it's the majority. You might know of whether it's the majority, but I think that there's certainly it requires both. Right. Either the development or strengthening of new connections and then the removal of other connections that decrease accuracy, say, or that don't allow you to do the exact motion that you were intending to do. This, like I said, kind of goes all the way back to the development of motor skills, say, in childhood. Right. The brain has kind of finished developing new neurons sometime around two or three Years old, Right. Beyond that point, you're actually primarily removing connections in order to refine functions based on the exposures that you have, be they language, motor, social skills, which is what the brain is essentially developing during that time period. So then that continues throughout our entire lives. And I think that something that happens later in life, one of the reasons why we may lose function is because we stop giving the brain inputs to maintain a given function. Therefore, that pruning continues. Right. I don't need to know how to do this, so I'm going to refer refine that away. That's kind of the developmental theory of aging or part of the developmental theory of aging. So in that, you know, when you're learning a skill as an adult or anytime, a big part of refining that motor patterns that you're developing has to be the removal of connections that are, or, you know, the downregulation of connections that aren't allowing you to do the skill that you want to do.

Dr. Andrew Huberman

If you were to tell people, look, you want to keep your brain as young as it can possibly be relative to your chronological age, you should. What, like it it. So this is a general brain health question, but really, I'm specifically asking about plasticity. And let's make it multiple choice, and then you can add things to it. Okay, you should exercise so it can be multiple things. And then we'll talk about which types of exercise you should continue to do, the things that you already know how to do. And then third option, not mutually exclusive with the others, of course, is you should try to do new things that you can't already do. I still toil with this. When I look at the literature on neuroplasticity and aging, right? Like, yes, use it or lose it is true. But we're also told that novelty and trying things that we're not good at is an essential component of building out brain circuits, continuing to make them function better as we get older. So how do you think about all of that?

Dr. Tommy Wood

I'll partly answer your last question and then maybe give a framework for how I think about it. So when you look at a combination of epidemiological studies and intervention studies in older adults where we think about maintaining cognitive function later in life, you definitely see that those who continue to engage in hobbies and activities that are cognitively engaged or cognitively demanding, and that can be lectures, that can be volunteering, that can be, you know, reading crosswords, that kind of stuff, those individuals tend to either have slowed rates of decline or better maintenance of function over time. And or lower rates of dementia. That's of course observational. Right. But that's usually people continuing to engage in the things that, you know, they've already been doing.

Dr. Andrew Huberman

Right. So they're holding on to what they've got.

Dr. Tommy Wood

Holding on to what they've got by continuing to do that.

Dr. Andrew Huberman

Okay.

Dr. Tommy Wood

Now of course it could partly be reverse causation because if you're maintaining function, then you will, you're more likely to continue to do the things that, that you enjoy doing. Right. So there's probably, it probably goes in both, both directions. However, there's an increasing body of literature that shows that by engaging older adults in novel cognitive activities, you see improvements in function. So that can be language learning, that can be complex coordinative movement or exercise. You see the same things with musical training, people learning a new musical instrument or learning musical theory, trying to identify different patterns in music. And you see in randomized controlled trials, improvements, particularly in executive function. That seems to be most common across those different interventions. Interventions. But you're seeing improvements in cognitive function with novel cognitive stimuli. There's a lot of recent trials that have also used types of brain training things like the pointer trial that was here in the US Maintain your brain, which is a massive online study done in Australia recently. And that's sort of broad cognitive training with like an online cognitive training platform. So again, it's a new or novel intervention or exposure that seems to provide a stimulus that improves function. So I think both can be or do seem to be important.

Podcast Narrator

I'm excited to share with you that my book, an operating manual for the human body is now available for pre order and will be coming out in less than two months. It's my first book and it's a reflection of decades of research, hundreds of conversations with leading scientists and medical doctors, and my own exploration of health, fitness and performance. Protocols is a straightforward to use manual for overcoming any number of different pain points you might have in terms of mental health, physical health and performance. And if you're already doing well with mental health, physical health and performance, it can make you that much better at

Dr. Andrew Huberman

any and all of those things.

Podcast Narrator

It's meant for anyone interested in achieving better health and vitality. It provides a deep dive into and clear explanation of tools to improve your sleep, nutrition, exercise focus, stress management, neuroplasticity and motivation, and much more. I'm truly thrilled to share Protocols with all of you. The launch date is September 15th. You can learn more about it by going to protocols book.com that's protocols book.com. i'd like to take a quick break to acknowledge one of our sponsors, David. David makes protein bars unlike any other. Their newest bar, the bronze bar, has 20 grams of protein, only 150 calories and 0 grams of sugar.

Dr. Andrew Huberman

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Podcast Narrator

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Dr. Andrew Huberman

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Podcast Narrator

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Dr. Andrew Huberman

ask what for an example of maybe one or two of the things that were in that large scale trial from Australia, like just at a very top contour level, older adults, meaning 65 and

Dr. Tommy Wood

older, are doing what the maintain your brain study was. Actually it was sort of midlife kind of 50s and 50s and 60s mainly. And they actually had interventions across four different domains based on risk factors within that given individual. So they had a dietary intervention, they had physical activity, they had cognitive behavioral therapy for those who had some potentially some mental health concerns. And then they had online brain training. There was something similar done in the pointer trial, which was in older adults now 60s and 70s. That was done here in the U.S. that was a replication of an older trial called the Finger Finger trial that was done in Finland. But what those guys did was something very similar. So it's a diet, exercise, monitoring and treating cardiovascular risk factors and then brain training. So what the brain training looks like. So the points trial is a good example. They use the platform called Brain hq, which is an HQ brain hq, which was developed based on the work of Mike Merzenich, who's like one of the godfathers of learning and neuroplasticity. Right. And they do various tasks primarily focused on developing and maintaining processing speed. Some of that evidence goes all the way back to an older trial called Activ that was done in the US in the 90s. It was still the biggest ever trial of like pure cognitive brain training again in older adults. So, 60s and 70s, they had three different training groups and then a control group. The training groups did memory training and kind of like mnemonics, memory palaces, that kind of stuff to help them remember. There was reasoning training, which is kind of like looking for patterns in numbers and letters. And then there was processing speed training, where in this example is visual processing speed. So things flash up on a screen in increasingly small increments, so could be hundreds of milliseconds. And as you get better at doing it, that time gets shorter and you have to remember what you saw and where you saw it on a screen. They just published a secondary analysis of the Active trial that showed that those who did processing speed training with booster sessions at one and three years had a significantly decreased risk of dementia 20 years later. And they've done some other studies showing that that kind of training improves cholinergic signaling in the forebrain, which we know is susceptible to the processes of dementia. So in particular, it's this training to be able to improve either visual or auditory processing speed, which is not something that as you get older, you tend to not do. Activities that require you to process information quickly, like driving is probably the main one, but you can do it in sports and music and other scenarios. But if you're not doing those things, processing speed tends to drop off sometime around 60 years old.

Dr. Andrew Huberman

When you say, well, I say processing, you say processing. Processing speed. Are you talking about reaction time improving reaction time or pushing people to stay at the edge of reaction time? And when I say stay at the edge, I should clarify for people some task where if you go too fast, you make errors, if you go too slow.

Dr. Tommy Wood

There's also a penalty in this scenario. And there are, you know, studies that look at these different functions over time. The biggest one looked at data that came from the implicit association test people might have heard of, where you show these pictures of different things, and depending on how quickly you respond, it tells you something about your implicit thought processes. They took some of the data from that. This was published in one of the Nature journals a few years ago. And what they showed was that you can separate out reaction time versus processing speed because reaction time is just the basic of response to a visual stimulus, whereas processing requires you, is based on how quickly you can process and remember the information that you're seeing. You actually think. Yeah. So what they showed in this study was that reaction time kind of slowly decreases, on average in a population of it was about 1.2 million people. Slowly decreases in sort of like from about our 30s, and then maybe decreases even more once we get past about 60. Processing speed, on average tended to be more stable until about 60 years old and then tends to drop off. So what you're doing in these training modalities is you're being shown information for a very short period of time and then having to remember what it was you saw and where you saw it. So it requires you to actually think and, you know, remember, process the information rather than just like responding to a stimulus.

Dr. Andrew Huberman

So for people that want to jump to the okay, what do I do? Can we conclude? Okay, if you like crossword puzzles, keep doing them, but do really hard ones for you. If you like lifting weights, continue to challenge yourself with those. If you like to run, you know, push harder. Or should it be we shift domains? You like to lift and run, Great. Start swimming again.

Podcast Narrator

Andrew.

Dr. Andrew Huberman

I'm telling myself I used to, I, you know, I just notice over time, it's such a cliche of aging, right. That you one does tend to become more narrow, quote, unquote, set in their ways. You like what you like, you don't want, but like, we don't. You get busier, probably don't actually get busier, but you convince yourself, well, I'm doing these things and I do plenty of them. So. But I'm not doing these other things. Or for those of us, I think this is everybody, if they really ask themselves an answer honestly, you'd love to hold onto your motor function and cognitive function as long as you can, maybe even improve it.

Podcast Narrator

Should we push ourselves to do something

Dr. Andrew Huberman

that's really far outside the box or maybe sort of current skill adjacent? So I think of those three categories, what do the data say? If you want the greatest effect for the minimum amount of time, assuming you're still going to do all the stuff you normally do, you're going to add something else. Should it be something really different, slightly different, or just push harder in the thing you do?

Dr. Tommy Wood

I think it's going to depend a little bit on what it is the things that you currently do. Right. So like crosswords are a good, a good example, even if you're doing hard ones. If you look at the work of people like Gloria Mark, the things like crossword and sudoku, they're less of like a true cognitive challenge, right. It almost has more of like a meditation, meditative like effect. Right. Which can be a good thing. Right. So you're focused, but not challenged, really. Whereas if we're trying to build capacity, you need to spend some time doing something where you are both focused and challenged cognitively. So that can come from learning new skills, be they motor, language, social, and ideally as broad as possible, because you're going to get better overall stimulus, as well as kind of broader potential for transfer into other areas of daily life. In reality, the narrowness of the response or the breadth of the response is proportional to the narrowness or the breadth of the stimulus. So you could get really good at one very specific thing, or you could try and learn a new skill that requires. That involves a wide variety of tasks. So I'll give like an example is learning a new ball sport, right. That is going to require multiple assets of motor skills, social skills. It's going to include both visual and auditory processing. That's going to get faster and faster and harder and harder the better you get. So something like that creates a much broader stimulus than if you get very good at one very specific brain training task on one computer program. This is one of the main arguments against online or digital brain training is that you get very good at doing that one specific thing, but it doesn't transfer over to other areas of your life. Whereas some of these broader, more complex, ultimately more human skills probably give us much broader transfer as well as, you know, because of the multiple pathways or networks that are being activated.

Dr. Andrew Huberman

If my interpretation of what you said is correct. Pick something hard.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Ideally pick something that's a bit outside or really outside your current skill set that involves motor and cognitive aspects, like maybe. And that's kind of tricky to find, right? I mean, with sports stuff, it feels motor and cognitive because you have to learn the rules of the game. You have to, in some cases, interact with others with cognitive stuff. The motor skills involved in writing or turning a page, they're not that significant, right. Even with a video game. I know video games can improve reaction time and visual search and things like that, but basically your thumbs get real, real good. I actually went to a video game competition. They have teams. A kid that used to work for me, I was like, what do you want for kind of end of year gift? And he was like, I really want to go to this Video game championship. And the kids actually who compete warm up their hands. The kids in the audience, like have these styrofoam things that they clap so they don't make noise. So they. And it was a whole thing.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

So I don't want to take anything away from the. The real sport I discovered that is playing video games. But mostly what was moving was thumbs and fingers. Not a lot of large scale motor activity. So if you had to maybe throw out three or four things that are particularly potent plasticity inducers, what would those be?

Dr. Tommy Wood

This definitely doesn't have to be super complicated. So like the things that you mentioned earlier, so you. Because you mentioned exercise and then skills. Right. And so you could do those things separately. Right. I would maybe we'll get into why aerobic and strength training do different things to different parts of the brain. Right. So ideally you do a little bit of both. If you don't feel super compelled to go and start a new sport, but you're getting these inputs from elsewhere and so you would rather say, learn a new language, which we have some good evidence for, then that combination is great. But if you're thinking about some of the things that we have very good evidence for that kind of hit multiple networks at the same time, dancing is probably, number one, learning a new dance, learning a new dance solo or with someone else.

Dr. Andrew Huberman

I'm sort of half joking, but some people dance on their own, some people dance with someone else.

Dr. Tommy Wood

So like dancing on your own in your living room, highly encouraged. Right. It's a great form, physical activity, it's fun. Of course, the, the best evidence is for ballroom and line dancing, which generally requires. And so there are meta analyses of these interventions in older adults showing that ballroom and line dancing have the greatest effect on cognitive function. And so both of those require other people as well as learning, you know, various sets of movements. So you have skill learning, you have social interaction. And the other physical activity component, there's probably also the musical component. Right. You have to listen for the timing of the music and those kinds of things. That is its own skill set. So dancing has a large body of evidence behind it. But then I think in the exercise realm, you've got all the sort of ball sports, board sports, team sports. I think skateboarding would be a great example. As long as you wear a helmet and don't hit your head too often. Most martial arts, again, as long as somebody's not punching you in the face too much.

Dr. Andrew Huberman

Something like Brazilian Jiu Jitsu.

Dr. Tommy Wood

Exactly. So there's a physical component there's a complex motor skill component. Usually there's a social component. There's a lot of responding, reacting to the environment or your opponent. So then talking about processing speed again. But then beyond that, there's some really interesting data on some other creative arts that do seem to have some effect on network stability and function in the brain. Particularly the networks like the frontal parietal network that we know is really important for focus and attention and its function does tend to decrease with age. So things like creative or visual arts, maybe some similar effects of learning a language again, similar effects from learning to play video games. Yes, of course there's no like big motor patterns involved, but you're having to do, you know, solve complex problems, you know, react quickly to a changing environment, that, that kind of stuff. So that's, you know, eight or nine different things that somebody could try and like just one of those I think is going to be a new skill, A new stimulus often happens in a social environment. A number of different things happening at the same time.

Dr. Andrew Huberman

Any particular instruments?

Dr. Tommy Wood

I don't think anybody's looked at instruments like the difference in different instruments. So I would say no, pick one. That you would. That you feel motivated and interested to

Dr. Andrew Huberman

learn dancing by oneself has a lower shame quotient.

Dr. Tommy Wood

Well, the shame quotient I think might be, might be important, right? There's the, you know, there's this, the discomfort of making mistakes. And we know how critical that is for learning. And so like you're, I think some of that can be important too. But if you do it in a class, everybody else is a beginner, you're all doing it together. Maybe that adds a fun component because you can laugh at each other when you don't get it right. So a few years ago I wrote a paper with my colleague Josh Turknett about this idea that potentially one of the reasons why we lose cognitive function as we get older is because we stop giving our brain novel inputs or complex inputs that help maintain function drive neuroplasticity. And I think one of the reasons that that happens is because adults hate being bad at things, right? You just like this thought like you, you, you just imagined it, right? I'm in a dance class and I'm gonna suck at dancing, right? I imagine that I'm gonna take my wife to, to a tango class. It's something I've always wanted to do. But when I go in the first time, I imagine I'm going to be like Arnold Schwarzenegger and Jamie Lee Curtis in True Lies. Do you ever see that? Movie. But anyway, so right at the beginning, they're like, they're spies and they're doing the tango at this gangster's mansion or something. And it's like he leans her over, she grabs the rose from the table in her mouth. I'm going to try that and I'm going to drop my wife and she's going to hit her. She's going to be mad at me and lots of people are going to see and I'm going to feel stupid. And so that's why we don't do those things. But it's so critical to driving those processes of neuroplasticity that we make those mistakes that we have to let go of some, some of that, that we feel as adults. Like we, we think that everybody expects us to be good at everything and the best at everything. And, you know, we shouldn't fail, we shouldn't make mistakes. But as you've covered many times, it's so critical to, to do that. And so I think acknowledging that shame component exists and leaning into it is going to be a really important part of trying to maintain this function over time.

Dr. Andrew Huberman

Couple of quick anecdotes and then some encouragement to do the tango class. I'll start with tango. My grandparents on my Argentine side did tango until they're into their 80s, so it can be done, but they learned it rather young.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

And Tim Ferriss, as I recall.

Podcast Narrator

Yeah.

Dr. Tommy Wood

Talked about dancer.

Dr. Andrew Huberman

Yeah, he learned tango. And, and that gets to the other point, which is I want to talk about sex differences and results of experiments in plasticity, but when you dance the sorts of dances that we're talking about, so salsa, tango, typically this is, you know, traditionally the male leads. Years ago I had a girlfriend who was really into salsa, so I went salsa dancing with her in the Bay Area one night. And it's, it's a tricky thing if you're not skilled salsa dancer because basically you're taking your girlfriend to go dance with a bunch of other men, you know, and then you, you until you learn. So the, the. It's, it's. There are conditions that make it harder, social conditions that make it harder for men to learn than women to learn particular types of dance. Unless, as Tim did, he got a dance coach, a female dance coach to teach him how to lead, and then he learned how to lead and then he was able to dance tango competitively. I think I have that right, Tim. They'll correct me in the comments, but as I recall, that's the story. So there's that. Not that following is, is trivial. It requires some skill. But the, if the person, and traditionally the male can't lead the whole thing, it doesn't work right. So I just made you more nervous about going to this class, but you should do it because I had a roommate when I was a postdoc who's a neurology resident at ucsf and she would go do tango late at night and she would come back a different person. And so this is like the other piece here is, you know, it seems that when we are trying something truly new that involves interactions with other people and we go into that willingness us to enter beginner's mind or whatever it is, embrace the shame, and as we start to get even just a little bit better at something, I mean, it almost seems like there's this kind of halo around the rest of our life. We go to work the next day differently, we interact with people differently. Like our nervous system is changed. What do you think that is? I mean, we can make up stories about chemicals and maybe we should because they're likely to be true. What do you think that is that like general change in arousal? Like you're sleeping better, you're. You're more excited for the other things in life when you're trying to learn tango and you get just a little bit better. What is that?

Dr. Tommy Wood

I don't think I would make up anything about, about chemicals. I think you could boil a lot of it down to we like to be good at stuff and we like to overcome things, right? This is like this, this like core needs to be challenged and then to overcome those challenges. And I think there's a lot of downstream effects of not doing that and they could be, you know, relates to mental health. It could also be related to physical health. Right? Because we think about physical and cognitive or, you know, stressor psychological related challenges and the process of overcoming them because that's what really drives, you know, a lot of physical or mental psychological growth. And I think that's something that, you know, fundamentally is part of what we need on a daily basis. And so you did this thing that you were bad at and you got better at it and you proved to yourself, hey, I'm capable, I'm able to overcome challenges. I'm able to, you know, engage and do difficult things. And I think the psychological benefits of that, you just. That process of engaging with a challenge, overcoming it, working hard to do that, I think that's just almost like a core psychological need that we have. And then that transfers to all these other things. Oh yeah. I can do these hard things, I'm going to do that other thing. I'm excited to try something else that's difficult. I'm excited to challenge myself again. And it needs to be something that feels meaningful, feels difficult enough that you have the ability to overcome with some dedicated practice or focus time working on it. If it's too hard, you can have the opposite effect. Making something so difficult, somebody can't do it and they just fail again and again and again and again. That can obviously have the opposite effect. But something that, you know, you can get better at, you know, you can work on, you can see progress. I think all of that then has all these knock on effects.

Dr. Andrew Huberman

Maybe we could talk about flow for a second. One of the most bastardized terms in neuroscience, performance psychology and the rest. When Csiksa Mihalyi talked about it initially, when he really defined the term, it was about being engaged in a process where you have a certain level of skill, but the thing you're trying to do is just beyond your skill level. So really striving a bit and that kind of general sense of well being that can come from that. Nowadays, I think people assume flow is when you are able to do something in the absence of kind of feeling of effort. It's like you get the magic power kind of thing, which is not what flow was originally intended to mean. I'd like to know how you think of this concept of flow and whether or not it's even a meaningful term. And I tip my hat to Steven Kotler and others who have written about it and studied it, and great respect for Stephen and what he's done with the concept and, and, and I think it's a meaningful concept, but I don't think we really know how to define it. And I think this is important in

Podcast Narrator

the context of plasticity because I think

Dr. Andrew Huberman

what we see in Harry Potter movies and sci fi and, you know, Fight Club and everything else is that suddenly we're just going to be endowed with these powers just because we want them and need them. And that is not how it works. So is flow an expression of skill or is it the striving to attain a skill?

Dr. Tommy Wood

I think of flow as the maximal expression of a complex learned skill. Like you said, you're right at the edge of your capabilities, but you're still managing to maintain function, whatever skill it is that you're performing at. The thing that really frustrates me is that because of that or some version of their definition of flow, people are like, well, I've always got to search for flow, everything happens in flow. Like we need to be in flow all the time, which doesn't make any sense to me whatsoever. There's two different parts of this. So one is that people assume that for optimal performance you need to be in flow. That is not true. Flow is one version of being able to perform at the best of your abilities. If we think about this in terms of sports performance, there might be broadly two states associated with, with top level performance. One is flow states, the other is clutch states. And so a clutch state, you are still at the optimal level of arousal, right. If we think about the arousal curve and performance, which we can come back to. But so at the optimal level of arousal, which is required for you to perform the skill that you're trying to perform, but when you're in a clutch state, it still feels like hard work, right? So like there are. You could talk to any athlete about a time that they, they performed well, they won, they, you know, they did the best of their abilities, but it was hard cognitive work, it was hard physical work, it was a slog, but they still managed to perform well. That's like, that's a clutch state. And people can perform at the best of their abilities in clutch states. And, you know, even though they're not in flow, it's not all coming to them easily. Right? It requires them to like, really focus and work hard to get, get the job done. And both of those are perfectly reasonable states in which to perform. And assuming that you have to be in flow to isn't true if you look at how athletes perform in the moment. The other side of it is that some people have intimated that flow is required for learning or optimal learning happens in flow, which doesn't make any sense. If we talked about making mistakes and errors and friction required for learning that is not conducive to flow because it can be stressful, it can be frustrating, and sort of the other side of that is if flow is expressing your skill, if you want to get better at that skill, you have to work even further beyond your current capacities, which will move you out of flow because of the friction, the mistakes and the errors that come from that. So I think flow is super interesting and I wouldn't pretend to be an expert in flow, but there are all these other states where learning happens, where performance happens, that aren't flow. And that's, that's fine too, right? But sometimes it's hard and that's okay.

Dr. Andrew Huberman

I'm so glad you're here. I've been looking for this conversation for. Well, since I started the podcast, because I completely agree about flow and the misunderstanding of the concept of flow. I've never heard of a clutch state. Is that a term that you coined or.

Dr. Tommy Wood

No, no, it's in the sports psychology literature they'll talk about.

Dr. Andrew Huberman

So that's why I haven't seen it. Yeah.

Podcast Narrator

Because I'm very familiar with the neuroplasticity

Dr. Andrew Huberman

literature, but I've never heard of it. Maybe I'm just not up, up, up to date on my reading. But thank you for introducing clutch state, which is when one is performing well, but it's, it's evolving. And this is a term I did make up sort of some limbic friction, like you have to push yourself. You're feeling constrained. It's that you're at that edge where it's. There's real challenge. You're not. You're definitely not in flow. Yeah, fantastic. Clutch state, everyone. Learn it, know it, embrace it, live there for some period of time in your life, across your lifespan, and you'll be better off. I, I mean that. Maybe we could drill into this a little bit more because, you know, several times on this podcast or more, we've talked about the anterior mid cingulate cortex, the structure that, you know, maintains size and superagers who take on hard things. And, you know, this area of the brain that seems associated with tenacity, which when stimulated, people feel like an impending challenge. There's actually neurosurgery experiments done by Joe Parvizi at Stanford. People feel like, oh, there's. I'm going to lean into it. This sounds more like the clutch state than certainly than flow state. So maybe the thing we need to embrace is the clutch state.

Podcast Narrator

It's pretty catchy.

Dr. Andrew Huberman

It's not quite as catchy as flow, but I like it because it has an element of friction kind of written into it. You heard it first from Tommy Wood, folks, not me, a good friend who comes from the special operations community. We talked about performance years ago and he said, well, there's unskilled, skilled mastery and virtuosity. Okay, cool. And he said, virtuosity is when someone who has mastery pushes out to an edge of effort where they're sort of inviting in the unknown. They don't quite know what they're going to do next. They have some semblance of an idea, like they're not being haphazard, but there's an inviting in of the unknown and they find themselves at a new level. I've probably mentioned this documentary four times in the last four episodes. But when Andy Stumpf, former Tier 1 seal operator, came on this podcast, former wingsuiter, Red Bull High Performance Team, came on here, he suggested a podcast that I'm now suggesting. He suggested, excuse me, a documentary that I highly recommend, which is the Dark wizard, which is about Dean Potter, who is a free climber, free solo climber, turn wingsuiter, et cetera. And you see that documentary how somebody

Podcast Narrator

who's pushing to their edge

Dr. Andrew Huberman

and a little bit beyond where the consequences, the death consequence is able to access levels of skill that are, like, jaw dropping, I think, even to him. So does that make sense? Like, is that sort of how you think about unskilled skilled mastery, virtuosity? Do you think virtuosity is, like, where someone is like, all right, I've mastered this thing. Now put me in a situation, or I'll put myself in a situation where I don't know what's going to happen and maybe it'll all go wrong. But when it doesn't, new levels of

Dr. Tommy Wood

performance emerge, as it's described that way. Because people might talk about virtuosos in a skill just because they're so much better than everybody else. Right. But that definition requires a specific scenario and moment of performance. Right, so then that sounds a lot like how I would think about flow. Right? And so, like, when you. When you look at some of the classic descriptions from individuals who've been in that kind of level. So, like, there's this one from. So I do a lot of work in Formula One. So there's one from Ayrton Senna, where he's from. Who? I'm sorry, Ayrton Senna.

Dr. Andrew Huberman

The driver.

Dr. Tommy Wood

The driver, yeah. Senna.

Dr. Andrew Huberman

Excuse me. Senra is David center, the great podcaster. He's the. He's the virtuoso of. Of performance and business and finance podcasting.

Dr. Tommy Wood

Don't let any of your F1 loving friends hear that part of the podcast.

Dr. Andrew Huberman

I like Senna.

Dr. Tommy Wood

Senna. Some people consider him to be the. The best Formula one driver of all time. He died tragically in. In a crash. But. But there's this famous quote from him where he's driving the Monaco Grand Prix. And basically what he describes is that he's going faster and faster and faster. He's like, this is beyond my capabilities. He doesn't feel like he's actually connected to doing the thing. It's just kind of, like, happening. He's going seconds faster around the lap than anybody else. And so that's kind of what he is so good. He achieved mastery and in that moment and he's displaying virtuosity under that kind of definition. And so that feels like there's a lot of overlap there.

Dr. Andrew Huberman

Yeah. Ever since seeing this Dark wizard documentary, which I've watched twice, all the way through because it has a mental health component. It's a brilliant and beautifully shot documentary recently released, I think about this virtuosity thing constantly. But I love this notion of the clutch state because it sounds to me that that's the state that we want to seek. And the assumption is that high performers are in this relaxed, mellow state. But I'm guessing they spend a significant amount of time there and drilling the really boring stuff to make sure they can get there. Twyla Tharp, who's in her 80s world class choreographer, sat in the chair that I'm in and described the daily routine of her world class dancers. They go through the most basic drills every single day, but every iteration for hours upon hours upon hours before they begin, quote, unquote practice, right before, before they try and embrace the, the new performance piece. But over and over and over, often after multiple hours of morning exercise. I think we don't see all of that foundational work and that it needs to be maintained. Which raises a question, do we always need to maintain practice the fundamentals.

Dr. Tommy Wood

Before I answer your question, I think there's, there's an another useful thing just kind of to remember that relates to all of this from, you know, in, you know, athletes and sports, particularly on the training side. There's this general idea of thirds, right? A third of your sessions, training, learning, whatever it is, are going to feel great, great. You're going to feel really good. You're just going to get stuff, you know, immediately. It's going to just come to you. A third will just be average, right. And a third are just gonna suck. And you just have to show up and get it done.

Dr. Andrew Huberman

This is all in the same day or this?

Dr. Tommy Wood

No, no, just a week across, across the week, across months, across years where this stuff undulates. And the, the main reason why I say that is because related to this sort of glorification of flow is this idea that these things should just like always come easily to us. But that's completely antithetical to the idea that we have to work hard and challenge ourselves in order to build capacity drive neuroplasticity. So there's kind of this weird tension between what people are seeking versus what is actually just the part of the grind of getting better over time. And sometimes it is a grind. And again, that's okay. It doesn't mean you're doing it wrong. Maybe it means you're doing it right. When you then think about maintaining the fundamentals, I think yes, but probably it's going to depend on the scenario that you're thinking about, because sometimes the skill that you're performing, the fundamentals are kind of baked into that in some way. So it kind of depends on what the fundamentals really are. Maybe if it's. So I'm thinking about one specific study that was done in pianists. So it was kind of related to the Erickson studies in violinists. But this time they were looking at pianists. And so they had four groups older and younger. So the younger was like 20s and 30s, older were 50s and 60s, expert and amateur pianists. And so the experts came from German music conservatories. And then they looked at sort of basic skills related to, you know, moving the fingers and other things that you would do playing the piano. And so there were very task specific skills related to piano playing. And what they found was that the most important predictor of how well somebody performed at those piano specific skills was not their age, it was how much they practice. So it's just that getting those reps in helps you maintain those sort of like basic functions. And maybe right when you're playing very complex piano pieces, you're encompassing all those fundamentals anyway. Right. You don't need to do your scales every day because some of that stuff is kind of built in. But you will also see people as they warm up, say maybe they will do scales and things because that's part of just like the warm up. Maybe that's routine, right? This is me getting in the mode of playing a complex piece, but then maybe some of it is just kind of helping to maintain those fundamental skills.

Podcast Narrator

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Dr. Andrew Huberman

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Podcast Narrator

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Dr. Andrew Huberman

So now's your opportunity to kill the 10,000 hours. I know other people have attempted to, but what does that really boil down to? Is it simply that about eight hours a day of practice for a dedicated period of time is what leads to rapid plasticity and that's what was measured? Or is there really some sort of rule about time under seeking clutch state?

Dr. Tommy Wood

The simple answer is what the study showed was that 10,000 hours was the average amount of time that an expert violinist had spent practicing by the time they reach 20 years old. That's what the study showed. They weren't even experts by that point. That was how much they'd practiced essentially in their youth. So that number of hours doesn't even translate over to true expertise in violinists in this one specific example. So I don't think there's some fixed number of hours required. It is interesting other parts of that study kind of looked at the practice routines of these expert violinists and what they found was that they tended to practice for about two sessions of 60 to 90 minutes a day. And I think that's a pretty good rule, right? If you're going to do something hard, you're pushing beyond your current skill level, focusing for 60 to 90 minutes, maybe with, you know, a couple of breaks in there a couple of times a day. That's probably about as much as most people can do. And I think that also relates to how we perform on a day to day basis in other areas of life, right? We kind of expect that we can go to work and we can work really hard for eight hours straight during the day. But like the brain doesn't really work like that if we're doing hard cognitive work, right? You're being, you're focused and highly challenged as you might be if you're a, you know, a future Virtuoso on the violin. And you're trying to, you know, really practice and push yourself. You can only really do that for, you know, chunks of 20 to 30 minutes, maybe a couple of times of the break. Right. So like, that's why pomodoro, even though there's no like good studies on the pomodoro technique, like for those time periods, you know, 25 minutes with a five minute break a few times, they do kind of fit into that kind of rhythm that translates over to multiple areas where we might want to use our brains. And just remember that hard cognitive work and that process of learning can only really happen in those kinds of size of chunks if you want to do them sustainably.

Dr. Andrew Huberman

Yeah. Before I started writing my book, somebody who's published several very well received books said you can only write for about four solid hours per day. Broken up into a couple of sessions. I was like, come on. I mean, like, I'm not trying to boast, but I used to go into the lab and sit down and work on a grant for six hours or something like that. And I started thinking like, was it really six hours? Go in there, see my students and postdocs, sit down. Okay. Then there was lunch. I need to walk my dog, you know, and there were some late nights, but then the next morning I'm kind of dragging because I was in, you know, in my office really late and. And you get real honest with yourself real quick and you go, oh, okay. In the periods of time where I definitely pushed to the 6, 8, 10, 12 hours of just non stop work, as a deadline approached, there was a compensatory drop in output after, after you click send. And so I, I think you're right. They're right. Somewhere between maybe, I mean, you're saying 60 to 90 minutes and they're saying four hours, but not a whole lot more than that. For real focused in clutch state work.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

So really digging in and no distractions, no phone, no checking your text messages, just, you know.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Do you ever give yourself forced constraints to get real work done, not to force it.

Dr. Tommy Wood

I will say that one of the best ways to like truly get deep, focused work done is to eliminate distractions. Right. That's one of the most important things that you can do. So close the email. I would like put my phone in a different room or something because like nowadays your own, you know, close Slack. I have Slack teams. My lab and I, we interact on, you know, message back and forth on WhatsApp. Like there's email. I've got like five or six different ways that people can like, constantly try and get my attention. Right. So, like, eliminating distractions is really important. And again, I return to Gloria Mark's work. She wrote an excellent book called Attention Span. If anybody's like, really interested in this, but you get used to a pattern of distraction such that when you're not actually being distracted, you will distract yourself. Right. But you can be trained out of that as well. But so you know that thing where you're trying to do work and you like, reach for your phone for no reason? It's because your brain is kind of used to this pattern of. Around about now, somebody will text me or send me an email and I'll reach out to my. For my phone. So you go looking for it even if it hasn't happened. But again, you can train yourself out of that if you, if you have periods where you're not getting constantly distracted. So I will eliminate notifications. But at least for me, what I found is that if I. If I have a ton of friction in terms of trying to get something done, I will usually step away from it because there's something in there that just like, needs to click or come back before I can like, really engage

Dr. Andrew Huberman

in it or if you're at a sticking point.

Dr. Tommy Wood

Point, yeah. So if I'm at a sticking point or it's like, if something feels like it's just not coming in the moment, I'll usually switch over to something else, which is also kind of a normal. It's one of a possible set of patterns of work, which is that you have two or three projects you're working on on any given time. If one just isn't quite working, then you can switch over to the other one and come back to it. And then the alternative is that when the deadline is so close, and this often happens with a grant deadline, or when I was writing my book and there's a book deadline and I've got to get this to my editor in however many days or hours. I tend to just not need to eliminate those things because I'll just focus in. I don't feel that kind of draw to be distracted by other things. But that usually only happens for relatively short periods of time. It's going to be a day or two or hours during a day rather than extended periods of time time.

Dr. Andrew Huberman

Are you familiar with this recent study about phone on the table, phone in the bag? We would just remind people that if your. Your phone has to be out of the room, even if it's in your Bag beneath your chair turned off, you can still focus, but there's a, a cost. Your cognitive flexibility, et cetera, really suffer. So that means that the brain is unconsciously expecting a call, you're waiting for it. And, and the way you describe this attentional break expectation thing that we get entrained to interruptions is really interesting. Maybe this is why meditation is such a useful tool for improving focus, is that it's just a forced no breaks thing. Although it's pretty easy to drift in meditation if you are not used to doing 20 minutes of meditation, you sit down to do that, you set the timer, your brain can end up way off the trail.

Dr. Tommy Wood

There could be some benefit to that as well. Right, because there's, you know, without kind of building that in. And I don't routinely meditate, but unless you have some part of your day where actually you're not either putting in information, distracting yourself, thinking about a specific thing, right. You don't necessarily get that time to integrate. You know, that's kind of, you know, the classic is you come up with your best ideas in the shower, right? Because actually the time when you don't have your phone on you and you're not watching TV and you're not not doing all these other things at the same time. So maybe, yes, that's not what meditation is formally for, but it could potentially be beneficial. If your mind's going to wander, making new connections, coming up with new ideas, having that space and time to do it could potentially be beneficial too.

Dr. Andrew Huberman

In these studies, these large scale trials, what was the diet intervention? Can we distill it down to some things that everyone should do or ought to consider?

Dr. Tommy Wood

Most interventions in the sort of cognitive and psychological space are focused on some version of the Mediterranean diet. There's the mind diet, Mediterranean intervention to prevent neurodegenerative delay. It came out of the Rush Memory and Aging project. And it's basically just a version of the Mediterranean diet, kind of focused on dementia prevention. And the way they initially created it was they looked at foods that people ate more or less of and created a score. And those who had a higher score tend to, you know, had a lower risk of later dementia. It wasn't an intervention when it was when it was first developed, but that was kind of diversion. It was kind of combination of the Mediterranean diet and the DASH diet, which is like a anti hypertension blood pressure treatment type diet. So it's, you know, seafood, vegetables, berries, whole grains, that kind of stuff, not

Dr. Andrew Huberman

too much saturated fat or animal protein.

Dr. Tommy Wood

And so this is Very similar to the diet they used in the SMILES trial, which was the first randomized controlled trial in depression that showed significant improvements in mood symptoms. I think the principles are useful, but there's not necessarily a huge amount of evidence to say that this is the way that you should or you have to eat to maintain cognitive health. There was actually a big trial of the MIND diet. It was published in the New England Journal of Medicine a couple of years ago, and they compared the MIND diet to standard caloric restriction, and actually they saw similar benefits in both groups. There have been big observational studies that have looked at how much their diet looks like a Mediterranean diet. And those whose diets look more like Mediterranean diets. Yes, they have a lower risk of dementia. Of course, this is observational data, so it's not. You can't say it's causal. But what's interesting in some of these studies, there's a big one that came out of the UK Biobank, was that that they took out individual foods or food components of the Mediterranean diet to see if that changed the relationship between the Mediterranean diet and dementia risk. And there was no food or olive oil or food group or eating more or less meat that changed the relationship between the Mediterranean diet and dementia risk. So what that tells me is it's much more about whole foods. They're nutrient dense, rather than avoiding any. You have to eat, you have to consume lots of olive oil. Right. Or you have to restrict meat, because if those things are eaten in the context of all this other stuff, it's really that bigger context of diet quality and nutrient density that really matters. So the parts of diet that I think about are there's three. So there's energy, there's nutrients, and then there's overall dietary patterns. So one of the confounding things about that trial I told you about, the MIND diet versus caloric restriction is you're like, well, the MIND diet should win out. How does caloric restriction do just as well? And in the kind of average population, we tend to have some issues with metabolic health and have been in a state of chronic energy excess for some period of time. There's been some very nice studies that have looked at that brain aging and brain volume or brain reserve across different populations. There was one group that looked at different tribes in Bolivia, the Bolivian Tsimane, who are hunter gatherer group, the Mercedin, who are kind of an intermediate group between sort of the Tsimane and like a standard kind of industrialized group, and then industrialized humans in the US and Europe. And what they found is this kind of this bell shaped curve between energy availability and brain volume, and in general brain volume, the more the better, we think. And so if you're chronically, calorically restricted, your brain is smaller because you just don't have the resources to invest in the structure and to maintain it. At the other end, you see the same thing. So if you're chronically in a chronic state of caloric excess, you also tend to have a smaller brain on average. And this is related to metabolic disease and potentially what comes with it, higher levels of inflammation, high blood pressure, things like that that we know can negatively impact the brain. So the most important thing, and I think this is where some of the benefits of caloric restriction happened in that trial compared to the mind diet, was that people's cognition improved just because they decreased their energy intake to a point that was more, was essentially what their brain needed, kind of supported their overall physical health, which then affects cognitive health and brain volume and brain function. So the first thing to do is to make sure that you're eating enough, but not too much. And that's very simplistic, but energy is really critical. Energy availability, not too low, not too high. Then the next thing that you need is nutrients. We know there are several critical nutrients related to cognitive function and risk of dementia. The ones that we have the best evidence for, vitamin D, iron, omega 3 fatty acids, the B vitamins involved, and the B vitamins involved in methylation. So particularly B12 and folate, also potentially B6 and riboflavin, although that might depend a little bit more on the individual. Then there are some other nutrients that have some pretty good evidence for them. So many of the antioxidant polyphenols, things that you get from berries, coffee, tea, chocolate, but the carotenoids that make things orange, yellow and red, lutein, zeaxanthin, astaxanthin, if it comes from seafood, that's what makes shrimp and salmon pink. And then some other aspects like dietary fiber seems to have some benefits as well.

Dr. Andrew Huberman

Not magnesium.

Dr. Tommy Wood

So magnesium is absolutely in there too. And in general, I think so. Magnesium, zinc, then there's some of the structural lipid components, things like choline and ethanolamine that you might get from nuts and seeds or eggs. They have some slightly less evidence really, when you're looking at brain changes over time and dementia risk, but they certainly do seem to be related to cognitive function. So there are some studies that show that those who have lower magnesium intakes tend on average to perform less well on Some, some cognitive function tests. So all of those do seem to be important.

Dr. Andrew Huberman

I have two questions about nutrients and brain health in the short and long term, and they have to do with interactions between nutrients, which, at least to my understanding, are rarely explored. You know, you'll see studies of supplementing Omega 3 or having people eat some fatty fish or, or less and so on, but rarely in the presence or absence of some other vitamin that you know that can potentially impact the same pathways. So there's synergy, there's also, you know, necessity. So that could impact results. The other piece is on what timescale are these nutrients needed and on what time scale are they metabolized? So maybe to just kind of drill into the second question first. So, you know, I'm not out here as like the defender of supplements, but I've been taking supplements in various forms and eating, eating whole foods and eating generally healthily, you know, less so when I was younger, but still pretty healthy, and more so as I get older. But here's where my brain goes, wait, whole food is great, but let's say dark leafy greens have a bunch of things in them that are fundamentally important for brain and bodily health. Great. And they have fiber, et cetera. How many times a week am I eating dark leafy greens? Let's say I do Monday, Tuesday, Wednesday, I'm great, but then I'm traveling on Thursday, Friday, should I be just supplementing Thursday, Friday, am I good until the next week? I think one of the reasons why eating really well, I think everyone knows what that means. Not enough calories, not too many, mostly whole foods, et cetera, enough vegetables, fruits, and high quality protein and quality fats. I think the reason why supplements still become enticing to me, maybe even necessary, is because you can take them every day very easily. So you can make sure that you're in range and maybe above range. So let's take one of these things, okay? Omega 3 fatty acids. I believe that the data are pretty compelling. They can be helpful for health, maybe even brain health. Certainly I believe that. But let's say the early part of my week is omega 3 rich, and the later part of my week is omega 3 poor. Am I good versus you know, spreading it out across the week. It just becomes difficult to eat in a truly healthy way if, if it's the case that it has to be consistent every 24 hours. So what do we know?

Dr. Tommy Wood

So again, I think we're often tempted to over complicate this and try and think, oh, you know, I have to hit all these things at this interval. And if I can't do that, then I have to supplement. And in reality, we probably have more buffer in the system than we realize. So omega 3 fats is a really good example. Your adipose tissue, your fat tissue is a depot. It kind of stores excess omega 3s. Actually, I wrote a paper on this with a colleague of mine, Rory Heath, a few years ago. The long chain Omega 3s that we have in our fat stores may help to explain why supplementation does or doesn't work in some of these trials. Because some people just have more kind of hanging around. And if you eat more than you need on one day, especially in a state of caloric excess, that's going to be stored in your fat tissue. And then when you're sleeping or when you initiate lipolysis, the breakdown of fat, so particularly during periods like if you're doing exercise size, those then get released and they, you know, the brain then has access to them. So there's some studies that show that when you. But this relates to the form of the Omega 3s as well. So many people will tell you that you have to take omega 3s in the phospholipid form, which is like a special, it's a special supplement. You can get it from krill. And the, the form is, with that the fat is attached to like a phospholipid head group, just like it would be if it was sitting in a cell membrane. And there's a specific pathway for those to get, get into the brain.

Dr. Andrew Huberman

It's only krill or it's fish oil also.

Dr. Tommy Wood

No. So fish tends to be the triglyceride form, which is your glycerol and then three fatty acids attached. When you compare a single dose of phospholipid versus triglyceride form, then more of the phospholipid form gets into the brain. Some of this, you know, most of this comes from rodent studies. But what's interesting is that if you supplement over several days, it all kind of comes out in the wash. Because the triglyceride form cycles through the adipose tissue as a depot and then it gets released and the brain can then use it. So if you're going to take just one day of supplement and you want to get as much of that Omega 3 in your brain, yes, you should take the. We think we should. You should take the phospholipid form. But the form that comes in seafood, which is primarily the triggers, triglyceride form, is regulated through the body's fat stores. So this is a really long way of me telling you if you eat some fish early in the week, you don't then have to supplement later in the week as long as you've got kind of enough. And especially if you've consistently eaten seafood across your entire life, because you probably have a bit of a depot. And so what you see in several trials where they've given omega 3s to decrease dementia risk or improve cognitive function, so many studies like that have been done. There was actually a very recent one that just came out of USC where they gave gave omega 3s for a long period of time. They measured omega 3 levels in the CSF in the spinal fluid of these people to show that the Omega 3s were getting into the brain. They didn't see any changes in terms of cognitive function or brain structure on an MRI scan. So everybody's like, well, omega 3s don't work. But when you kind of squint at the data and they didn't quite give me the data that I wanted. But when you look at it, the people in the trial just didn't seem that Omega 3 be deficient in the first place. So, right, if this isn't something that you need more of to start with, giving a load more of it isn't going to make that much of a difference. Right. And this is the case for all of these different supplements. So the best advice, if you have access to it, is to test your levels. Test your vitamin D levels, test your hemoglobin and iron levels, Test your Omega 3 levels, test your homocysteine levels, which is as a marker of B vitamin status, which we know is a, a risk factor for cognitive decline, dementia as well. So if, if you can test your levels and it shows that you need more, and yes, there are the, the normal ranges that you have on a blood test are not necessarily the same as the risk ranges. So homocysteine is a good example. A normal range for homocysteine which goes up. If you need some of these methylation dependent B vitamins, the normal range might go up to like 15 or 16. But we know that risk is definitely elevated above 13 and is probably elevated above sort of 10 to 11. So what your target range really might be is probably lower than what the normal range might be. But we have very good evidence that if you then supplement when somebody is above that range and you bring that down, you see significant improvements in cognitive function or slowed cognitive decline. That is particularly the case for omega 3s and B vitamins. That lower homocysteine. And so this is the interactions that you were talking about earlier. And this is the best one that we know of, although I'm sure there are many more. Like I said, there are lots of trials that have given omega 3s or have given B vitamins to lower homocysteine and just haven't seen much of an effect. And everybody goes, oh, well, they don't work. But there are now at least three randomized controlled trials that have shown that Omega 3 status and B vitamin status interaction and they're dependent on one another. So if you give B vitamins to somebody who has elevated homocysteine, you bring down their homocysteine, but they have poor omega 3 levels. You don't see any benefit. And that's been shown in two trials. It was originally shown in the Vitacog trial that was run out of the University of Oxford. It was then replicated in the B proof trial. Then the other side has also been shown. There was in the Omega AD trial, they showed that supplements with Omega 3s didn't result in any benefit if people had elevated homocysteine. So that's just one example. And you can imagine, like you kind of said, there are probably lots of these. And if we're not, you know, going into a study actually looking like, well, what nutrients does this person need? And then supplementing with them, you're not going to find any effect. You shouldn't be surprised when there's a. When the study doesn't show anything. Potentially the one recent example of kind of just giving a broad based kind of set of nutrients with a multivitamin that seemed to work fairly well was the Cosmos study people may have heard of. It was thousands of people of older adults and they were given either a multivitamin or a flavonoid supplement.

Dr. Andrew Huberman

Like a Centrum type vitamin.

Dr. Tommy Wood

Yeah, it was Centrum Silver, like the most, most basic multivitamin, just 100% of the recommended daily allowance. No massive doses of anything. And in that study, those who got the multivitamin saw changes in cognitive function that suggested some improvements, but that was literally just covering the bases. No massive doses, the most basic multivitamins. So in the kind of general population, I think you could say that something like that is probably a reasonable strategy. But what they also showed was that that supplementing with this antioxidant cocoa, flavanol was only beneficial in those who tended to have a poor quality diet to start with. Right. So they just weren't getting many of these kind of compounds for their diet. If you're drinking a lot of coffee, eating a lot of berries, seeing a lot of fruits and vegetables, you probably don't need it because you're already getting it.

Podcast Narrator

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Dr. Andrew Huberman

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Podcast Narrator

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Dr. Andrew Huberman

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Podcast Narrator

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Dr. Andrew Huberman

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Podcast Narrator

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Dr. Andrew Huberman

I look forward to a day, hopefully not long from now, where people get their blood work done, they are told and they decide it's a collaboration after all. Which supplements to take. Ideally, those supplements are tailored to them, so it's not not gazillion tablets and capsules and then they can redo their blood work and see whether or not things come into range. And of course that should be measured against subjective experience of well being and sleep and all of that. That's not hard to do in today's environment of technology and trackers and blood testing, it's just that we're a little bit still in the 90s even. Just the way that most people talk about supplements, certainly not you. But I think when people hear supplements and they go, oh, it's expensive. Urine, okay, that's vitamin, mineral, some of that is just getting urinated out. But then there's food replacement supplementation, and then there's supplements to get a specific desired effect, like speed up the transition, time to sleep, get more slow wave sleep, more focus, et cetera. So it's unfortunate that we don't have good nomenclature like we do in science, where, where. Where words are very important so that people can communicate with accuracy.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

And I also wonder whether, okay, if, if 1 gram of omega 3 EPA per day is good, but maybe 3 is better, even though I'm at upper reference range. And this is something that nobody really wants to address because then it sounds like biohacking. But ultimately I think people want to feel good, they want to live longer. No one wants to do anything dangerous. I feel like we're really like in the. In like prehistoric times with, with how we think, how most people think about nutrition and supplementation. I feel like the last 40 years have been spent mostly focusing on what's bad for us. Okay, Trans fats, bad. Fried food's bad. Eating too much bad. Right. Energy over energy toxicity, bad. Too much alcohol bad. 0 is better than any, but you could probably drink a little bit and be fine. Okay. If you're gonna take nicotine, don't smoke it or vapor dip it. Like, we sort of figured it out, right? Don't hit your head. If you do, don't hit it twice. You know, like, we've sort of been spending so much time on the don'ts that now I feel like we're in this exciting time of what can you do for one's health? And then there's this divide, right? Just eat whole foods, you'll be fine. And you've actually convinced me that we'll be fine. The question is, could I be that much better?

Dr. Tommy Wood

This is really interesting to me because there's two different parts to it potentially, although they may end up being the same thing. So one is, if we're thinking about. If we're thinking broadly about improving brain health, cognition at the population level, what's really important is kind of raising the floor, like, what is going to work for everybody and get most of us most of the way there. So, like, that really is improving food quality and Then access to those foods as well. Right, because that's different. That can be very inequitable. Like, can people afford it? Do they know how to cook it? Can they access it? And then within that, I think we also know we have very good evidence for cutoffs that predict risk. And if you can't get those nutrients from food, I think we should supplement. I think I like to call nutrients. The great leveler of there's no point in arguing about different diets because your body requires these nutrients and I don't care where you get them from as long as you get them. So if you need to get them from supplements, I think that's fine. Should be fine. When you then get kind of to the next level, like, how much further can we push function? My answer is, I genuinely don't know. Like when you say, like if I put. So if I. If I test my omega 3 and your omega 3 index, right, you said it was at the kind of the higher level. Maybe it's seven or eight or something like that. All right. If you push it to 12, is that better? I genuinely, genuinely don't know. Like some of these more complex AI systems, data collection, kind of seeing how you then respond individually. As long as you can perform your own sort of personal experiments, right. As much as you can hold one variable constant, have some meaningful output that you can kind of track over time, see whether it works or not, can we then aggregate those data to kind of better understand this? I'm excited to see where that goes. I will say that the best evidence we have just says is in reality, don't be deficient. If you can reach that threshold of not being deficient or insufficient, maybe that's enough. I'm hopeful that that's the case. Right, because then more people will get to that point more easily. But there's a lot that we have to learn there.

Dr. Andrew Huberman

There was a time in the 90s and 2000s where people would take stuff and do stuff. I'm not talking about anabolic steroids, although that was happening too. And the whole idea was find things that work, perform really well in one's job or in one sport, assuming you're not breaking any rules, right, but not tell anyone you were doing it. And what changed, I think, were two things. One is there became a market value for telling people what one does in order to make money. So people started doing that. And I do believe sharing is good.

Dr. Tommy Wood

Right.

Dr. Andrew Huberman

But also there's this problem that goes with that, is that people who sit on the outside of kind of Brain and sports performance or just life just trying to maintain memory and do well in school and be a busy person and still get sleep and all of that feel like, oh, you know, we're being sold this one thing that's supposed to make all the difference. And I think the thing that really came in and changed all of it are the GLPs. I've never taken a JLP, but I'm just struck by like Americans are now willing to inject themselves, themselves. So now it opens up this whole thing about peptides, which, you know, the major consumers of peptides are not the bro science guys like the gym bros. It's women who look, I have female family members, right, who have. And they'll tell me and, and there's a long history of people doing and taking things and doing things for their cosmetic appearance and not necessarily sharing it with the world. So these are the performance enhancing substances of, of a whole different kind. Right. And so how is it that this peptide industry is so intriguing to so many people that, yeah, like jabbing yourself with something that is not FDA approved, like people are doing it like crazy. Even people who are kind of cautious about what they'll do and put into their body because of this bridge that the JLPs have made, it's so much easier now to just. People aren't as needle focused. So I think we're entering a time now where people are saying, okay, you know what, the government, the food pyramid, the whatever, the food quadrants. Like, yeah, that's just like if you don't want to die, but I want to feel great. And there's actually this potential that you and others are sort of offering. Like you can learn things into your older age, you can be lean and have great posture into your 60s, 70s, 80s, 90s. We see examples of this. So I think that there's, there's this pull, we're getting kind of pulled forward towards this promise. And I don't think that promise is all about avoiding the, the bad stuff. And people say, oh yeah, well my grandfather lived to be 102 and he was smoking every great, like awesome.

Podcast Narrator

But a lot of people don't have

Dr. Andrew Huberman

those kinds of genetics in their family. They really. And genetics play a big role. So I'm kind of editorializing here. I'd love your thoughts on how you sort of sit back and you look at the landscape of things. Eat right, exercise, get good sleep, socialize is awesome. But that is just, that is difficult for people. That puts people into a clutch state just trying to do that. While managing family and profession and cost of life, you know, cost of living, that's a lot. So I think people do want something that gives them more energy, gives them better sleep, you know, picks up their mood, you know, and I don't think there's anything wrong with thinking about those things as long as it feeds back to, to better behavior.

Dr. Tommy Wood

Particularly when I think about this kind of, this new part of the, of the supplement industry. And like you said, the, the, you know, peptides are just the next, they're the next iteration of the pills and potions and things.

Dr. Andrew Huberman

Supplements more than drugs. Because look, there's no putting the genie back in the bottle. I don't care what the FDA does and they can, mark my words, people are going to find their way to get their peptides because they love of them. And most people are not playing a drug tested sport. And there may be adverse events out there. And this isn't a plug for peptides per se. But where are all these adverse events that are not from botched injections or from really bad black market sources? Where are all the roid rages of peptides? Where are all the, like, I think you can see way more plastic surgery like, like, whoa, that looks bad kind of things. And it's like, okay, melanitan is kind of an issue because people can really mess themselves up there. But where are all the adverse events? Until people start dropping dead from BPC injections people are going to get and they're going to take their bpc.

Dr. Tommy Wood

I'll admit I'm more conservative when you're trying a new supplement or peptide. I'm going to include peptides into this. But of course it could be a pill or whatever, right? Some peptides come as pills. I would want to want some reasonably good evidence of efficacy that this is going to work in humans like me. That's probably not a bar that most of these things are going to hit anytime soon.

Dr. Andrew Huberman

No, people don't care. I mean people who, who have no interest in walking into a gym are contacting me like crazy. These are adults who have kids they love, spouses they love. They are not medicine phobic like traditional medicine phobic. And they're like, should I be taking low dose? Should I be microdosing terzepat or red or true Tide? I'm like, red or true Tide is not even released yet. They're like, where can I get it? Like, are you kidding me? You know? But it's, it's incredible what's happened in the last few years.

Dr. Tommy Wood

So think about what might, what you might think about if you're going to start to consider one of these. First of all I would want to see evidence that it works. The majority of peptides don't have good quality evidence in humans except the GLP ones right there on the market and

Dr. Andrew Huberman

the growth hormone secretags but for reasons other than people are taking in.

Dr. Tommy Wood

Yeah, yeah. Sarcopenia, you know other and, and with, with the most of those growth hormones creator cogs come with a risk of insulin resistance, diabetes at high, you know, particularly at higher doses.

Dr. Andrew Huberman

Yeah, they're not the super popular ones. I think the super popular ones are besides the GLPs and retatrutide is a GLP and other things. But are I would say microdosing of retatrutide and tirzepatide 1 category for weight loss, fat loss. I would say BPC 157 people are taking it without even knowing what the desired effect is.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Recovery is again really broad. I think it's injury repair. That's the thesis. No human evidence as far as no good human evidence. And then there are these other kind of dot dot dot ones. I would say ghk copper for skin appearance. Those are the three biggies that sit team and the last one in particular with women.

Dr. Tommy Wood

So I would want evidence that in humans it does what I want it to do. Most of those if not all of them except for the GLP ones don't, don't have that evidence or for the thing that you're trying to get. Right. But beyond that a question that you have to ask and I like this reframing. I heard it recently, I heard it recently from Jeffrey Blake Land which is that if you're going to consider injecting or taking something the first thing you should want to know is is this safe? Right. If you have good safety data then trying it is low risk. Right. Even if it doesn't work. Right. At least you know it's not dangerous. But we don't even have that for most of these.

Dr. Andrew Huberman

No, we just have the absence of documented adverse effects.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

And in the time course that they've been used because we don't know about

Dr. Tommy Wood

long term use use and so everybody has their own risk tolerance. Everybody's welcome to do whatever they want of course but for me personally first I would want documented evidence of safety and then you can say well I'm willing to try it because it may or may not do this thing but you should also have a specific problem that you're trying to solve. Otherwise why would you bother taking it? But it's also the case for the vast majority of supplements that are out there and have been around for long periods of time. Time is, first of all, we don't have good evidence of long term safety at whatever dose that you're taking. And then second of all, we don't know whether it works.

Dr. Andrew Huberman

For some we do, like creatine, omega

Dr. Tommy Wood

3s, magnesium and creatine is actually the best. So like omega 3s, we know that they're a critical nutrient. Creatine, I think, is the best example because we know it's very safe. Right? So even though this idea of creatine responders and non responders, you know, maybe it's going to be useful to improve or support cognition for some people and not others, may improve physical performance for some people, not others. At least we know that you can give high doses of creatine to frail older, older individuals with essentially no side effects, right? We know it's very safe. So then you can try it and see if it benefits you. So creatine is a great example, but there aren't that many others that kind of fit into that category.

Dr. Andrew Huberman

Interesting times. Again, I go back to, I love the idea of, of blood testing, tailoring supplementation to the needs of the individual retesting so people can be really objective about whether their levels are moving in the right or wrong direction. Subjective experience. The sleep supplementation thing is kind of interesting because either people feel it improves their sleep or it doesn't. Even if it's a placebo effect, which in some cases it could be with sleep tracking, people can see, are they getting more rem, are they getting more slow wave sleep? Such a fascinating area. I mean, as you and I both know, there's no plasticity pill. But arousal, alertness, focus seems to be a prerequisite of plasticity, which is why things like caffeine and stimulants and L tyrosine and all these things that you can find some evidence for them improving plasticity, but it's very likely to be indirect, right? It's not that they make you learn, they set the stage for learning. It seems to always get back to arousal. So this is, I want to get back to exercise as a tool for opening the window for plasticity. Could it be that it's simply a matter of moving your body to get enough adrenaline in your body, norepinephrine in the brain, and maybe some dopamine as well, so that the stage is set for plasticity and it doesn't Matter whether you jump rope, do jumping jacks, sprint, or do deadlifts, it's all about getting your brain into an altered. Altered, admittedly endogenous, chemical altered state of just more arousal, and then, boom, you can go learn. Is it. I mean, could it just be that

Dr. Tommy Wood

before we get into the exercise, there's an interesting part with the supplements that increase arousal? Right. So the stimulants in particular. And I am a big proponent of thinking about or tracking how somebody feels. Right. I think that how you feel is this kind of ultimate integration of all these inputs and outputs that the brain is kind of bringing together. Right. And we know that how you feel. So how an athlete feels is a much better predictor of their performance than their HRV or any of their blood tests.

Dr. Andrew Huberman

What are you asking them? Like, how good do you feel today? Yeah, I'm one to ten.

Dr. Tommy Wood

Some. Some version.

Dr. Andrew Huberman

I feel like I can conquer the world.

Podcast Narrator

1.

Dr. Tommy Wood

I feel like exactly on. You know, and you. You can boil it down, or, I mean, you can spread it out to many more questions. So there's. There's a question there called the rest queue, which is all about. About, like, how you recovered, how recovered you feel, how motivated you feel to train or perform that kind of stuff. But essentially it boils down to how. How good you feel. If you feel good, you're more likely to perform well. And that works better than the vast majority of data that you. Like, biological, physiological data you can collect. There are papers that come out on this every year that essentially show the same thing.

Dr. Andrew Huberman

That's kind of cool.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Because mindset, as my colleague Ali Crumb has focused on so much like. Like, mindset can be. You can be honest with yourself, and you can lie to yourself and tell yourself, like, okay, you got a lousy sleep score, but, like, I feel good.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Or I'm. You know, maybe sleep scores are like, they mean something. But today, you know. Right. I mean. And it can work, right? I mean, in terms of performance.

Dr. Tommy Wood

Yeah. And so. Absolutely. Right. Then that gets into the, like, the nocebo effect of how we think about. About either our sleep data or these other things that can negatively impact our performance. And we have good studies that show that as well. So I think that tracking how you feel is really important. But when it comes to stimulants in particular, they seem to dissociate how we feel versus how we perform. So there are studies that show that giving people caffeine makes them. Them feel like they're performing better, but they're actually performing worse. On certain cognitive tasks. So there's been studies done with the NBAC tasks, very complex working memory tasks, Particularly as you get to N3, you're trying to remember, did I see this letter three letters ago? In those kinds of complex cognitive tasks, people who take caffeine feel like they're performing better, but they're actually performing worse. They're making more errors or they're reacting too quickly. They're not really thinking about it. And there is similar data from other stimulants, too. So there was a paper that came out in science a couple of years ago giving people methylphenidate or some of the other ADHD medications. In people who don't have adhd, these stimulant medications again show this dissociation between. So they feel great.

Dr. Andrew Huberman

It's like the inverse of the cannabis thing, where people think they've got all these great ideas, more creative, and then the next day, even they are like, oh, my goodness, this is dreadful.

Dr. Tommy Wood

Yeah. And that's again been formalized in studies where you can do these tests where then other people objectively see how creative were you. People taking cannabis felt like they were more creative, but actually they weren't. And so the reason why I say this is that when we're talking about supplements, all these other things, we're like, well, I feel much better, therefore it must be doing something good. We know that with many of these supplements, you can create this dissociation between how you feel and how you perform, Whereas some of these endogenous things don't have that effect. Effect. So that's why that kind of like endogenous increase in arousal. Using things like exercise is a much more reliable way to improve performance because you don't kind of get this association between the two. So with exercise in particular, we know very well that some period of exercise can be resistance training, aerobic exercise, very brief sprints, increase arousal, improve cognitive function across multiple domains, improve, improve learning and retrieval. Right. So you're definitely augmenting some of these processes of neuroplasticity. Some of that's going to be related to the catecholamines and other things that get released as arousal increases. But we also know that different types of exercise have different effects on different parts of the brain. So, yes, I think some of just the general process of moving your body and exerting effort definitely increases arousal, definitely improves cognitive function, improves learning, as long as it's not truly exhaustive exercise. Like anybody who's done some terrible crossfit wad or I used to Be a rower. We used to do a 2K test on the rowing machine. You do a 2K test on the rowing machine, your brain does not work afterwards. It's like a six minute flat out, VO2 max kind of level of exertion.

Dr. Andrew Huberman

Yeah, thanks. I'm going to interrupt briefly. Thank you for pointing that out because I think, think that people assume they have an infinite amount of energy and there's crossover. And I certainly have done, you know, extra sets to failure in a great morning workout. And then in the afternoon I'm dragging. If I hold back just a little bit in terms of volume, I find I get a real boost out of training. I do low volume, high intensity, usually two sets per exercise, two or three exercises per. Per muscle, like quadriceps being one muscle or something like that. If I do three, it's a small addition. Right. The rest of the day I'm kind of dragging. So leaving something in the tank.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Does seem worthwhile. Not during the sets, but leaving something in the tank in terms of volume really seems to help, especially if you

Dr. Tommy Wood

want your like to perform hard cognitive work directly afterwards. Sometimes if you're trying to really push, sure, performance or adaptation. Right. Is worth digging into that hole, but it really just depends on what you want to be able to do directly afterwards.

Dr. Andrew Huberman

I think student athletes, especially in D1 schools, they really come to appreciate this. I've had a few of them in my courses over the years and they really understand when they're pushing very, very being pushed very hard in their sport. And they know that they have to sit in the front of the classroom, sit upright, do ex. Take extra measures to make sure they're not dozing off, attention drifting. Especially in the age of phones and iPads and, and things like that, it's very, very difficult. Yeah, thank you for, for mentioning that. Because they're just an extreme case of the rest of us. You know, we're told we're all very busy, like, oh, you need to exercise. It'll help your brain and be like, well, I exercise and I'm exhausted. You know, that's not helping my brain. Let's get practical here. So is there any way to. It's got to be really subjective and depend day to day. Is, is there any way to kind of formalize that? Like should you, you train, let's say resistance training or running, you know, should you cap it at an hour? Should you pull back on the intensity if you have harder cognitive work to do in the afternoon? We all want the maximum effect of exercise, but we don't want it to undercut our efforts.

Dr. Tommy Wood

Yeah, I think that a lot of it's going to be based on what your current capacity is. Right. As, as with everything. So if you're, you know, you want to do some, you've got some, you know, learning to do, you've got an exam, you want to do some hard cognitive work, work at whatever it is, writing a presentation, analyzing data, reading papers, writing a book, then doing some kind of workout that's probably below your kind of typical or below what you would do when you're really sort of pushing the envelope. I think that when you look at meta analyses of exercise and then cognitive function immediately afterwards, the, the protocol that has like the best evidence for it is like a 20 to 30 minute jog. Right. So like that's the kind of level of activity that really seems to sort of like support all those general processes of plasticity and learning.

Dr. Andrew Huberman

What do you think is going on? Because it can't be that much arousal. I mean the amount of catecholamines released from again, catecholamines folks, being the, you know, adrenaline, norepinephrine and dopamine generally really increased levels. Arousal, alertness, propensity to move. You just. That's that I feel better. People often think about the runner's high and endorphins. The endorphins come from pretty long, intense duration effort. They're more of a, you're floating kind of like, you know, I think the catecholamines are really the, the cocktail of like, all right, I got a great workout in this morning. Showered, got dressed, I'm off to work. Let's go. That's the. So 20 or 30 minute jog. I don't expect you'd get that much catecholamine release.

Dr. Tommy Wood

I mean you'll definitely get some. Right. And like cortisol two. Right. Which obviously increases alertness and arousal and can. Can in the short term make you feel good.

Dr. Andrew Huberman

It's a good thing. Yeah.

Dr. Tommy Wood

You see similar effects of, you know, short resistance training workouts. I think of it, it's probably a little bit of like an area under the curve thing because you see some similar effects of like you go out and you do six second really hard, hard sprints, like max effort sprints. You do that a few times with a long break in between. Right. That seems to have a similar effect. But you're only working for very short periods with very long rest periods. So it's something in that sphere. And I think that's probably just it. It's just enough to just kind of boost catacombies a little bit. A little bit of cortisol. That's enough to kind of move you up the arousal curve to the point where you're then able to focus and engage a little bit better. I think, yeah, you don't need a huge dump of that in order to achieve that increase in arousal, particularly as it pertains to learning and then cognitive performance in formal cognitive tests, which is where this is usually done. If you're then thinking about the type of exercise that changes cognitive function or brain structure, long term effort and intensity do seem to matter a lot more. But, but those studies have looked less at, well, how did that, how do they feel directly afterwards? Right now you're thinking about what's the kind of stimulus that drives change over time. And then intensity matters a lot as well. So the best example is with aerobic exercise on the kind of zone two up to kind of zone four, five sprint spectrum. So most people who listen to your show are probably familiar with a study where in older adults they had them do a brisk walk, walking three times a week, 40 minutes. And when you kind of read the study and, and the heart rate levels they were trying to attain, it was basically zone two work, 40 minutes, brisk walking three times a week for a year. And they saw significant increases in the volume of the Hippocampus, increases in VO2 max fitness, increases in circulating BDNF levels. Though circulating BDNF doesn't actually get into the brain, but it's kind of telling you something about crow leaf BDNF that's being produced in the brain and improvements in memory with all of that. However, there's a much more recent study that took again older adults and randomized them across three different groups. One was like a low intensity group. Another group basically did kind of Zone 2 type work on a treadmill three times a week. Very similar to that previous study that I mentioned. And the third group did a high intensity interval training, training intervention, which is the Norwegian 4x4 protocol. So four minutes 85 to 95% of maximum heart rate, they had a three minute rest in their protocol. They did that four times over. That's really hard. Anybody who's done the Norwegian 4x4, if you then say, well, hey, do that three times a week for six months, like that's three times a week. Three times a week for six months, that's pretty intense. But what they showed was that that high intensity interval training group, they improved their fitness just as well as the Zone 2 group, interestingly. But they had much better improvements in hippocampal function and maintenance of hippocampal structure on an MRI scan. And they maintained that benefit for five years after the six month intervention. So they worked really hard for six months, but that that benefit was maintained for, for a really long period of time. And in several analyses within that study, they basically show that the harder people work worked and the more cortisol they released, the better the benefit. And so this is important because nowadays there's, or, you know, there's several people out there saying, oh, don't do high intensity exercise. It releases cortisol. That's stressful. Your body can't handle it. Right. This study directly shows that working really hard, releasing a lot of cortisol in high intensity interval training actually improves hippocampal structure and function over, over time. So yes, I imagine after they did their workouts, their brain wasn't maybe working at its best because that's a hard workout. But over same, this was this really strong stimulus that then resulted in significant improvements.

Dr. Andrew Huberman

Forgive me if you said it and I missed it. What was the form of exercise? Was it rowing or biking?

Dr. Tommy Wood

It was on a treadmill.

Dr. Andrew Huberman

Treadmill. Yeah. Really interesting. And you said it about 85 of max heart rate.

Dr. Tommy Wood

Yeah. So that's, that's a typical Norwegian 4x4 protocol. But I don't think that's the protocol you have to do. I think it's just this process of high intensity exercise that it releases a whole bunch of myokines and lactate in particular. We know that lactate very easily gets into the brain, generate, you know, stimulates BDNF production as kind of part of that support of neuroplasticity or augmenting recent neuroplastic processes. I think there's something about that, just that high intensity work that drives some of those factors that then support structure and function.

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Dr. Andrew Huberman

A.comhuberman yeah, two things, super interesting comparison between these studies and as somebody who incorporates one day a week of 4x4 type exercise and one day of longer slower cardio, maybe I'll should try maybe doing a bit more of the high intensity.

Dr. Tommy Wood

Well I think if you want it to be sustainable for long periods of time, like I would typically say one day of high intensity work is fine. Right? Because you probably you want to be doing some resistance training.

Dr. Andrew Huberman

You're doing that three days a week. I do one long slow for me jog of about 60 minutes, 45 to 60 minutes and then one kind of moderate, kind of maybe more like zone three four. So thank you for, for putting in a strong word for cortisol, not always being the bad guy.

Podcast Narrator

People are so afraid of cortisol.

Dr. Andrew Huberman

You want your morning cortisol high. It's going to make you sleep better at night. You'll have more energy during the day.

Podcast Narrator

It was interesting to me to dive

Dr. Andrew Huberman

into the literature on cortisol and find that a moderate intensity resistance training session or cardio session probably a little bit easier, heavier than the 4x4 will triple one's baseline levels of cortisol and like or quadruple it. It's transient but nobody's freaking out about these workouts. But they're afraid to get in a cold shower which doesn't have nearly the same impact on cortisol or it's kind of wild how afraid of cortisol people are. People think they're going to get Cushing syndrome. It's been, I don't know what the psyop on cortisol was all about but you know you're to going to get moon face, you won't be able to lose abdominal fat. I mean there is a real condition which is you and I know it's Cushing syndrome where cortisol is pathologically elevated. But come on folks. Like cortisol goes up, Cortisol goes down 20, 30 fold from the morning until night in a healthy individual. So what do you think it is that people get afraid of cortisol? Afraid of some stress like your hippocampus, Obviously in this case, their hippocampus got better. It's not dissolving into a puddle of its own tears. What is this? What did our predecessors do wrong? You know, let's blame it on the parents because we weren't doing science communication then what in the world was the incentive for like demonizing molecules? It's so crazy.

Dr. Tommy Wood

So even though his framework, frameworks are still potentially very helpful, some of it we can blame on Hans Selye and his general adaptation response. The original idea that if you were chronically stressed, it would lead to true exhaustion of all your physiological systems. Because that was the final phase of his general adaptation response. People have conflated acute stressors versus chronic stresses. And yes, we know chronic stress, be they psychological, physical, increased allostatic load code increase, metabolic disease, inflammation, blood sugar dysregulation, insulin resistance, significantly associated with heart disease, dementia, all these kinds of things. So we know that these chronic stresses can be really detrimental to our health. But we've kind of conflated that any stress is bad because chronic stress is bad. But the way that I think about it, or I try and talk about it, is that actually the stress response? And this is as kind of cel originally described, it is stress drives adaptation. He called it general adaptation syndrome or general adaptation response. Because what stress is is your body acknowledging that you need to respond to some external stimulus, right? And so stress diverts resources so that you can then adapt to that stimulus, Be they physical, cognitive, neurological. Right? A stressor diverts glucose to the immune system, right, in, in an infection so that it functions better, you can eliminate the infection. And so yeah, if you took somebody and you like, you measure their cortisol levels after a workout, it actually looks very similar to how it would look if you just broken your arm or if you were like really sick, right? But this is the body adapting to a stimulus. And like everything we've talked about here, physical training, driving neuroplasticity, that requires adaptation. And so some of that core stress response is involved in that, the release of catecholium as you talked about in the brain. Those are stress related molecules that are driving adaptation so that your body can deal with the stressor better in the future. And we also know actually that there's some evidence for the cross stressor adaptation, particularly with exercise. Right. So. So if you exercise regularly, you are better at dealing with other stressors like psychological stressors. You're more robust to stressors. Your mood or your cognitive function doesn't dip as much when you're then psychologically stressed. So stress is actually really important because it's the fundamental driver of adaptation. But because we've kind of, we know that chronic stress is bad if you never get a chance. And that's because you never get a chance to adapt, you never get a chance to downregulate, you never get a chance to respond because it's just continuous but intermittent exposure to these stresses is really important. And Celia also talked about the idea of hypostress not having enough stress because then you don't adapt, you don't build function and response. So we just need to think about them very differently because those acute stresses are incredibly important for driving adaptation.

Dr. Andrew Huberman

Way I think of it is pick your stressor. You can either be exercise or it can be psychological stress. If you take it in the form of exercise, you probably have less in the form of psychological stress. It's obviously not completely true at a one for one, but I think as you pointed out, we and all organisms thrive on some degree of stress. I think if people are getting enough good sleep at night, yeah, sleep is the, I don't wanna say there's no limit to the amount of stress they can absorb, but when it starts to erode your sleep, that's perhaps when things need to be adjusted. Resistance training. Is there a particular protocol for resistance training that opens the opportunity for plasticity better than others that is supported in the literature.

Dr. Tommy Wood

Literature Again two different windows say of, of action. So there's that, that acute kind of arousal and this would be, you know, you, you go in the gym, you do a couple of sets, you're not maxing out, you know, it's, it's probably going to be your fairly typical couple of sets of 8 to 12 reps, kind of 80 of, of max, something like that. You do compound movement. So most studies use machines.

Dr. Andrew Huberman

Right.

Dr. Tommy Wood

So maybe do a leg press and a chest press and a lat pull down.

Dr. Andrew Huberman

Okay.

Dr. Tommy Wood

But multi joint movements, multi joint movements usually with machines. And again if that takes 20 to 30 minutes, that kind of shows some similar effects to that 20 to 30 minute jog that I talked about in terms of some acute bumps in cognitive function, probably through arousal, mild activation of those arousal pathways. Actually quite similarly though the, the, I mean probably slightly higher Intensity will also be beneficial as long as you're able to recover over time like that. That, that recovery is, is critical. Just like I was just saying, in terms of any kind of adaptation, There are several studies of resistance training looking at cognitive function and brain structure over time. I say several. It's like three or four in older adults. And they typically do do two or three times a week, five to six exercises, three sets of eight to 12 reps. Very, you're very similar. So those multi joint machines in the gym that anybody can do, they're in any gym.

Dr. Andrew Huberman

Presses, pull ups, rowing, pull downs, leg press, hamstring curls. Exactly.

Dr. Tommy Wood

Okay, yeah. And what you tend to see is that if you do that for at least six months, so the studies go on for like six to 12 months. Months, you see significant changes in the structure of the white matter of the brain and with that improvements in executive function in particular.

Dr. Andrew Huberman

Do you want to remind people what white matter is? Just for the newbies?

Dr. Tommy Wood

Very broadly, you have white matter and gray matter in your brain. In the human brain, white matter makes up approximately 60% more than most other species, any other species. And so the wrinkly outer part of your brain, the cortex, that's gray matter. Yours more gray matter deep inside the brain. In between that is the white matter, which is where you have the myelin sheaths on your axons. That's what allows those nerves to conduct information really quickly. Whereas aerobic exercise on that kind of intensity spectrum we just talked about seems to particularly benefit the gray matter, which includes the hippocampus. Resistance training seems to particularly benefit the white matter. And so you see improvements in a white matter structure which. And changes in white matter structure with age are one of the best predictors of cognitive decline with age. Interestingly, outside of other things, you see in terms of neuropathology, amyloid tau, et cetera, that loss of white matter structure and function is closely tied to cognitive decline over time. So you see improvements in structure and function of the white matter and potentially improvements in something that we call white matter lesions, which tend to happen around areas of poor for blood flow within the Y matter of the brain. And with that improvements in executive function. So aerobic exercise is gray matter and memory and resistance training is Y matter and more sort of executive type, decision making, processing speed type functions. We talked about lactate and some of these other things that might increase BDNF with the aerobic training. In resistance training, training. I think the primary mediator of that or one of them is IGF1, which is in particularly increased with resistance training. We know that IGF1 is really critical to the development of white matter right in the womb and then as a baby. And it seems to be also really important for white matter structure then throughout the lifespan. So resistance training is a really great way to then create these boosts of IGF1. So that's probably part of why we see that difference, but that's why you need to do both. Though they may have similar kind of acute effects in terms of cognitive function, they seem to be having very different effects in terms of the structure and function of the brain long term.

Dr. Andrew Huberman

I so appreciate that you're basically telling us that different forms of exercise impact different critical aspects of brain structure and function. So resistance training, white matter, cardio, gray matter, broadly speaking, and many different molecules, IGF1, BDNF, lactate and on and on. Just for, how do you say in Britain it's not kicks. They use a different word, but for kicks and giggles. I'll just tell you. There was sort of two running jokes in the field of neuroscience when I was coming up, which was if you desperately need a thesis. Fortunately this was not the position I found myself in. If you desperately need a thesis and like it's not going well, study the effect of pretty much any compound on REM sleep because it will reduce REM sleep sleep. There are very few things that increase REM sleep, very, very few, except sleep deprivation and then REM rebound. Likewise, there was a review published by a guy named Jeff Lichtman and Josh Sains who were in a different field. So they did a kind of cocky thing. But they, back then they were like, like they're good guys, I know them both. But they published this review about long term potentiation where they said, they did a review of the literature and they said basically you can throw any molecule on a couple of neurons and do

Podcast Narrator

the protocol for long term potentiation and you enhancement of long term potentiation.

Dr. Andrew Huberman

Now that wasn't completely true. The reason I'm raising this is that there's this theme, right? Like it's. There are certain processes, like processes that are not that hard to disrupt, like REM sleep. You just kind of tweak the system a little bit. You see a deficit, small or large deficit, and then things like long term potentiation, which is thought to underlie a lot of forms of learning and memory. In a dish with some neurons or maybe even an animal, you can knock something out or overexpress something and whoop, you get more or less long term potentiation. It's not that hard to tilt the scale on it. But in reality, the human body has tons of molecules that it deploys and it now to me makes perfect sense why plasticity, which of course is the foundation of learning sort of one and the same in many ways is brought about by resistance training and by, by cardiovascular training. Because they're both motor. Yeah, just like crossword puzzles. Certain plasticity effect, maybe less than, you know, dance, where there's a number of different things, social inputs, balance inputs, and on and on. So whereas two, three years ago I would have said, all right, are we really talking about exercise opening plasticity? This always seemed like mice running on wheels and you get a few extra

Podcast Narrator

neurons, you get a nature paper like,

Dr. Andrew Huberman

I love that work, don't get me wrong. But it turns out, out to not be that meaningful in terms of new neuron production. Isn't that doesn't seem to be that meaningful for human memory and offsetting cognitive decline. So. But now I have a completely different view of exercise based on your work, based on the studies that you're describing, because it's like, yeah, these are the big guns in terms of deploying lots of molecules that without question are interacting with one another. So I no longer think about exercise as like, okay, well, it's just increasing vessel growth. You're getting more metabolic health, so then the brain gets better. I now think about resistance training and cardio and their various forms, as you pointed out, four by four, et cetera, as like the real plasticity triggers. So that was a long winded way of saying thank you to you and your colleagues who've been doing this and thinking about things like clutch states and molecules that shift plasticity. Because, because I love reduction of single molecule manipulations. I think they're very important in a certain context. But for a while it was like, gosh, everything opens plasticity and everything disrupts REM sleep. And like, when are we going to get to this stuff anyway? Alzheimer's, Parkinson's, nobody wants these neurodegenerative conditions. What is the current thinking about the factors that make one susceptible to Alzheimer's? Alzheimer's. I'm beginning to think that it's not just one. But then there's a genetic predisposition issue that maybe you could touch on. And what can we do besides the things that we're already talking about today to best reduce the chance of accelerated cognitive decline or full blown Alzheimer's?

Dr. Tommy Wood

First we talk about dementia. Dementia, which is essentially the end stage of cognitive decline. There's some trajectory of decline that happens from your peak to that point where ideally we'd intervene much sooner. But right now we don't really do much until dementia is diagnosed. But it's very similar. We don't do very much until diabetes is diagnosed. Ideally, we can act much earlier in that trajectory. And that's increasingly being accepted in the neuroscience and neurology communities that actually we could potentially change that trajectory or at least decrease risk. And so within dementia there are as an umbrella term, which is essentially the loss of cognitive function, such that you can't look after yourself on a day to day basis, you can't do the sort of the basic activities of daily living. Alzheimer's disease is the most common. It makes up about 60 to 80% of cases of dementia. The next most common common is vascular dementia, although vascular dementia and Alzheimer's disease overlap a ton. Like, the vast majority of people who have Alzheimer's disease also have some element of pathology or changes in the blood vessels in their brain, which is what you get with vascular dementia. And then there's also dementia with Lewy bodies, frontotemporal dementia and then dementia related to Parkinson's potential, although that overlaps a lot with Lewy body dementia and, and dementia. And Parkinson's may just be. May actually mostly be Lewy body dementia. But we've gotten to a point now where it's generally accepted that potentially half of cases of dementia are preventable. And I think the majority of that falls into those first two buckets, Alzheimer's and vascular dementia. Although metabolic disease and other risk factors for Alzheimer's disease also increase the risk of Parkinson's disease and those other dementias as well. When you then think about Alzheimer's disease specifically, there's one small slice of Alzheimer's which is like monogenic dominant mutations that you have in either. Most of them happen either in the presenilin genes, presenilin 1 and 2, or the amyloid precursor protein gene, they make up at this point less than 5%, maybe as little as 1% of Alzheimer's disease. So we set those to the side a little bit. The vast majority of Alzheimer's disease is what we would call late onset Alzheimer's disease, although it's happening actually early and earlier in some populations. Yes, the genetic component, your APOE gene, is probably your most common risk gene. It's also associated, there's also polygenic risk. So thousands of genes can give you a little bit more, a little bit less risk of Alzheimer's disease, but it's much more related to lifestyle and the environment than say, that kind of early onset monogenic Alzheimer's disease. And the best accepted review of all of this is run by the Lancet Commission on Dementia Prevention overseen by Professor Jill Livingstone. And the most recent version of this suggested that there were 14 risk factors who between them accounted for about 45% of dementia risk or dementia cases. And there are modified, identifiable. So early life education, high blood pressure, diabetes, hearing loss, vision loss, brain trauma, high high cholesterol. They recently, recently added high ldl, high LDL cholesterol, low physical activity. So this is all related to the things we've already talked about. Right. Maintaining good physical health. Maintaining, maintaining inputs, getting inputs in the first place. Right. Education is, is, is critical.

Dr. Andrew Huberman

And hearing loss, as I recall, was an important one.

Dr. Tommy Wood

Right.

Dr. Andrew Huberman

In reference to, to inputs like you don't want sensory input degrading.

Dr. Tommy Wood

Absolutely. So hearing loss, vision loss, social isolation, they didn't, it was quite. So two things they didn't include that were fairly controversial and were sort of debated, letters were written to the editor and all that kind of stuff as happens in, in academia, related to. So they didn't include sleep loss or sleep deprivation as a risk factor for dementia, even though the evidence, particularly if

Dr. Andrew Huberman

you're didn't look at it or didn't

Dr. Tommy Wood

include it, they didn't include it. So like they talked about it, but they felt that the level of evidence wasn't high enough, though it was probably as high as some of the other things that they included.

Podcast Narrator

It's a tricky one.

Dr. Andrew Huberman

I don't want to take us on too much of a tangent, but having looked at these data a lot, I do think that people need to get enough sleep. But some people like myself do fine on six and a half or seven hours and other people can do fine on only seven or eight or nine. Very few people are a okay all the time on just four to five hours for prolonged periods of time. But, but when we say not a

Podcast Narrator

okay, what tends to happen with shift

Dr. Andrew Huberman

worker people that are chronically sleep deprived is most of the other things you're talking about get worse. LDL goes up, stress. So it's, it's like I can understand why they might not have included it, but it seems so foundational to me that it does seem kind of a shame.

Dr. Tommy Wood

Part of it is related to how they analyze the data. So we can, we can, we can get to that. But I mean in reality, when you look at the data on sleep loss and dementia risk, the cutoff is really around six hours hours. So if you're consistently sleeping fewer than six hours. That's where risk starts to increase. So that. That kind of.

Dr. Andrew Huberman

Yeah, that sounds about right. Because it's the. I think it's a la. It's the lack of those last two cycles where that are REM enriched.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

You know, because in the beginning of the night you get your growth hormone surgery, you get a lot of deep sleep, assuming you're, you know, doing things right during the day. And, and then it's those last, you know, two 90 minute ish cycles that you glean most of your REM.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

And if you're not getting those night in and night out and night in, night out, like sooner or later you're going to have issues.

Dr. Tommy Wood

Yeah, yeah. So sleep was one, then the other one was nutrient status. So they didn't talk about omega 3s B vitamins, which we do actually have some quite high quality interventional and observational kind of epidemiological data for. So there was kind of some discussion as whether those things should have been included. Other analyses that looked at those suggested that they potentially contribute a significant of the amount of the population attributable risk of dementia. So all that to say that their 45% estimate could be quite conservative. If we consider some of the other things. There are some other studies that suggest that as much as 70% of dementias may be preventable. But then you have to start including things related to socioeconomic status and deprivation and other societal factors that we know have a massive impact as well. So that's less modifiable on the individual. Individual level.

Podcast Narrator

Right.

Dr. Tommy Wood

It really would require a lot of changes at the societal level, which is kind of harder to do.

Dr. Andrew Huberman

Can I ask you a question? It's going to be a very controversial one, but there are people arguing, there are very smart people, I should say, arguing that the shingles vaccine is lowering rates of dementia significantly. I haven't looked at those data closely yet. I plan to. But it certainly is intriguing given the. The data that herpes viruses of various sorts have been correlated with Alzheimer's.

Dr. Tommy Wood

This comes off the back of three or four very large natural experiments that have been done in various countries. And really how you interpret these data is going to depend a little bit on your kind of risk tolerance and what you think should be done in terms of the level of evidence required to intervene. So I'll describe the studies in a second. But some people are definitely saying if you want to say that the shingles vaccine decreases dementia risk, you have to have a clinical trial that's adequately powered to show that. And there is a trial like that being planned currently. So the studies that have happened so far, there was one in the UK in Wales, one in Australia and one in Canada. And in each of those countries, what happened was that on a single date, a huge tranche of people became eligible to get the shingles vaccine, whereas if they were born one day earlier, they weren't eligible. So you get what you call like a natural experiment where from one day to the next, those people shouldn't be that different otherwise. And they showed that rates of other diseases weren't that different. Rates of uptake of other healthcare and other vaccines wasn't that different. But there was a big shift in the uptake of the shingles vaccine. And so what they essentially consistently showed across all those different populations was that those who got the shingles vaccine or were eligible to have the shingles vaccine, depending on whether they had access to the data, on whether people got it or not, had a decreased risk of dementia. And that was consistently seen across those three groups. All those three trials used an older version of the shingles vaccine called Zoster Zostavax, which was a live attenuated vaccine. There's now a newer version called Shingrix, which is a recombinant vaccine. And there was a study done in the US that compared people who switched from. There was a similar switch from Zostavax to Shingrix and saw that Shingrix was associated with a lower risk of dementia compared to Zostavax, although both were associated with a lower risk than none. When you look at some of these trials or studies, because they're not trials, people have made a very fair comment, which is that when you look at the trajectory of dementia over time, you look at something called a Kaplan Meier curve. So it's like a survival curve. So like every time somebody gets case of dementia, like, the line goes up and you look at the trajectory of the two lines, those who got the vaccine or not, they diverge very early. Early, which kind of says that, oh, it only takes a couple of months to kind of see this difference in dementia risk, which you wouldn't really expect based on the natural course of dementia. Takes years to happen. So this is very common in these kinds of studies and it's due to residual confounding. So there's something inherently different about the populations that may be driving some of this different. They were going to get less dementia anyway. And so maybe, maybe the shingles vaccine isn't having that big of an effect. But I would say that having looked at all those trials and all those data, I'm fairly. I'm convinced enough that there's a signal there. There should be a randomised controlled trial that's happening. But there's a number of reasons why this might be the case. One, obviously, we know it reduces cases of shingles. Shingles can be. Be very painful. It can change how people interact with the world. You stay at home, you don't feel good, you're in a lot of pain for a long period of time. That can go for many months. It's rare for it to last many months, but it can last a long time. Then they've hypothesized in some of those papers that the magnitude of the reduction of dementia risk didn't map perfectly onto the reduction in cases of shingles. There had to be something else going on as well. They've suggested that it may be due to an immunomodulatory effect. It may be because you're also suppressing other viruses like herpes simplex virus, that we know may also be associated with certain cases of dementia or Alzheimer's. And the reason, one of the arguments for the immunomodulatory effect is because not in all the studies, but in most of the studies, there's a slightly bigger signal in women than there is in men. And it may be that. That sort of meaning it's more effective, more effective in women than it was in men.

Dr. Andrew Huberman

And we should mention that the shingles virus lives on neurons.

Dr. Tommy Wood

Yes.

Dr. Andrew Huberman

Yeah. The herpes viruses tend to live on neurons and they hang out on neurons, which is why people who get herpes 1 infections will get a. A cold sore at a particular location that will come back because it's living on the trigeminal nerve. It's just, you know, I think people don't often understand that viruses can harbor in particular cell types. And so the logical link between herpes viruses and dementia risk is, you know, it's not. I mean, that alone is not a causal relationship, but it makes sense mechanistically. And a fundamental feature of herpes viruses is they generally don't kill the norm. Iran they can, but that's why they stay alive. These viruses are very smart. They know how to get infect their host but not kill their host, which is what really smart viruses do.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

So what age are people getting the shingles vaccine?

Dr. Tommy Wood

The study is actually quite late. It's like people in their 8, 70s and 80s.

Dr. Andrew Huberman

Oh, wow.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

Okay.

Dr. Tommy Wood

So again, it would be very fair to argue that getting it much earlier, we don't have any evidence for. Because, you know, in reality, in these, particularly in these, the studies like the uk, this is done in the national healthcare system. It was for the highest risk older adults. And so getting it in your 50s or mid-50s, which is sort of the guidelines in the US that yes, to reduce shingles, absolutely, but it doesn't map onto the dementia risk age that was seen in these studies. A final piece of this that I think is important and kind of goes beyond just the shingles vaccine, is that if you want to maintain function over long periods of time, one of the best things you can do is minimize your chances of getting really sick. There have been several studies. One was the Adult Changes and Thought study done at the University of Washington in Seattle. Primarily a similar thing was shown in the Rush Memory and Aging Project. But basically, when you at look at the same individual over time and you measure their cognitive function every few years, which these studies did, cognitive function doesn't just decline linearly or steadily with age. It goes down a little bit on average. But the biggest decreases happen stepwise after periods of significant illness. In the Adult Changes and Thought study, those who'd been sick in between had a major illness in between having their cognition retested, they had a step change down. And those who were hospitalized, that step change down was even bigger. So you could talk about how people maybe could have changed things in order to recover some of that function afterwards. I think that would have been possible if we thought about how you might intervene. But a major. I think it's a reason to say if I can do as much as I can to minimize the chance that I get really sick. Because what happens then is I'm at home, I'm not receiving any stimuli, any inputs, I'm not moving, I'm not eating well. Obviously there's all the downsides of the infection itself. Then if I can avoid that as much as possible, then over time that could lead to greater benefits, change the overall trajectory. So I think that's one reason why some of these vaccinations could be beneficial is just you're minimizing the time you spend really sick as you're older, which we've seen as results in these sort of like step changes down in cognitive function.

Dr. Andrew Huberman

Fascinating. I realize that we could and probably should do an entire podcast about traumatic brain injury and concussion, but as a teaser for that, are there anything that people should do and. Or take. Take in the immediate aftermath of a head hit? Now I'm not talking about, hopefully people are getting checked out for brain bleeds and things like that. So I'm talking about moderate concussion. Someone got their quote, unquote bell rung, they slipped and fell, they got clipped in soccer practice, their kids a little dizzy. Now, of course, somebody young or old is vomiting or, you know, not able to sleep or real issues. I mean, everyone should probably be checked out in the first case. But I get asked this question all the time. Is there anything that people can take to kind of get over mild concussion or moderate concussion?

Dr. Tommy Wood

The evidence base on this is a little shaky, but I think for most things it kind of fits into this idea of positive asymmetry.

Dr. Andrew Huberman

Right.

Dr. Tommy Wood

Low risk, high potential for benefit. And there have been lots of, you know, there have been randomized control trials that kind of look at some of these things. So we, a couple of years ago, we published a paper looking, looking at different nutritional supplements after concussion that, you know, we have some reasonably good evidence for. So, yes, you should be seen by a doctor. You should get whatever scans and, you know, immediate medical care that you need. Absolutely right. That's. We're assuming all of that is done or will be done. Yeah, immediately. There are a couple of things that I think we know from sort of animal studies that translate fairly well onto onto humans, but also some, you know, maybe some observational studies in humans. But a couple of things are important. So one is temperature, temperature management, temperature regulation. There have been. This is what my PhD was actually in. Hypothermia after acute brain injury.

Dr. Andrew Huberman

Hyperthermia.

Dr. Tommy Wood

Hypothermia, yeah. So cooling down. Although I did do some studies where we heated up and that makes things worse. So this kind of pertains to what I can imagine.

Dr. Andrew Huberman

Brain doesn't like to get too hot.

Dr. Tommy Wood

That's essentially what I'm about to say. So there have been lots of studies where they've done cooling hypothermia in people after traumatic brain injuries and concussions hasn't really shown much of an effect. What seems to be important is preventing hyperthermia. So one of the effects of cooling somebody down is that they don't get hot. So that's probably something that's really important. So often concussions happen in a heat, stressed environment. You're on a football pitch, it's August In Alabama, it's 40 degrees. Right? Get inside, get cool as quickly as you can. Because there are studies. That doesn't mean you have to get an ice bath. Just don't be really hot. If you get a fever, which you might, might do after a more significant injury, you know, Tylenol or something like that to help maintain thermoregulation will be really important. The next is blood sugar regulation. So we know that after a significant brain injury you have increases in, in blood sugar that's associated with worse outcomes. Some of it's like what's caused, what's consequences. The injury driving the blood sugar. Is the blood sugar driving the injury? I think an easy thing to just say is I would avoid any super sugary, refined carbohydrates that might just sort of, you know, kind of pile on, for want of a better word. Right.

Dr. Andrew Huberman

About alcohol.

Dr. Tommy Wood

So alcohol I would avoid as well, mainly because it impairs sleep and we know that sleep is going to be critical to recovery. Some people would say something similar about caffeine acutely after injury because it's a, it's a stimulant. One thing that the reason why hyperthermia, you're getting too hot. Hot makes the injury worse is because it simply speaking, increases the gap between energy requirements and energy production. So one of the hallmarks of these acute brain injuries is a deficit in energy production with mitochondrial failure or mitochondrial dysfunction. And so if you get too hot or you stimulate the brain, you're asking for more energy when your neurons can't produce it. And that is a trigger. That kind of deficit in energy production is a trigger for cell death and neuroinflammation and some of these other processes that then may happen. So avoid alcohol, avoid caffeine, both of those potentially related to improving sleep. Then things that we have some reasonable evidence for immediately after concussion are creatine at what dosage? The best trial was actually done in a pediatric group, although very broad. It was like 11 year old to 18 years old, but they gave 0.4 grams per kilo per day. So.

Dr. Andrew Huberman

Whoa.

Dr. Tommy Wood

Yeah, so it's, it's a pretty, it's like double a traditional loading dose if you're a hundred kilo person, but like if you're seven, if you're 70 kilos, you know, 155 pounds or something like that, then that's 28 grams of creatine. So like it's a lot, but trips

Dr. Andrew Huberman

to the bathroom could be expected, but you would just spread it out across the day, right?

Dr. Tommy Wood

Yes, so. So. Well, one thing I'll say about that is the most recent meta analyses show that you actually don't get. It's actually quite rare to get more GI side effects with creatine compared to placebo. Some of it is probably related to the quality of the supplement. So poor quality creatine supplements have more adulterants that may cause some of those GI side effects. Some of it can be due to high. You can saturate the creatine transporters, it doesn't get absorbed. Water gets drawn into the gut. That can then cause diarrhea or something. But some of the GI issues that people experience are probably due to poor quality products that they're taking.

Dr. Andrew Huberman

For the non head injured individual, is there any reason to go back to the old loading protocols of taking 20 grams per day, putting it in a little bit of grape juice or something else to spike blood sugar for this very reason that it could augment the the passage of creatine into your cells as opposed to drawing water into the gut. In the 90s we would take 5 grams of creatine four times a day in an ounce or two of pure grape juice.

Dr. Tommy Wood

Yeah.

Dr. Andrew Huberman

And you draw a lot of water into your muscle cells. You put on. You know it varies but for me anywhere from 5 to 8 pounds of it's water weight. But it's mostly in the muscle muscles. It's not insignificant translates to big strength increases. I don't take nearly that much now. I just do the 10 grams per day. But is there any reason to go back to those traditional loading.

Dr. Tommy Wood

So if you're just like long, like long term creatine supplementation, probably not in this kind of setting. I think the evidence is for a loading style protocol. Right. So for most people it might be 20 to 30 grams of creatine spread across the day. If anybody's just taking creatine for other reasons, this is a standard dosing protocol I think is fine.

Dr. Andrew Huberman

I thought you were going to tell me I could get it to work that way.

Dr. Tommy Wood

Some of the studies that use traditional creatine monohydrate and look at creatine levels in the brain, they did use a loading protocol for a week and then you see significant increases in brain creatine. But creatine having other effects on the brain, potentially improving mood, improving, improving memory. And in older adults some of those benefits happen at just like a traditional creatine doses. So you don't need to take massive doses. You know, think loading doses. You can actually see some benefits of like 5 to 10 grams. So that's creatine. So magnesium, so 400 milligrams once or twice a day. There have been some trials that shouldn't what form those studies actually use magnesium oxide, surprisingly. But I would probably use magnesium glycinate. The, it's very bioavailable. Athletes usually need a bit more glycine anyway. But any bioavailable form will, will be fine then. O omega 3 fatty acids. The evidence is, is, is a little bit better for like there are now several studies in like America, in like collegiate American football players where they take a couple of grams of omega 3s every day and across a season you see less accumulation of biomarkers of injury like neurofilament light that are circulating in the blood. So that's something that I would just take longitudinally. If you're somebody who's at risk of a concussion because of your sport or your job, I would just take a reasonable Omega 3 supplement just long term because we have some reasonable evidence for that. Then other things might become a little bit specific to the symptoms that you're experiencing. So if you have sleep issues then there's studies that have used melatonin and that's shown in improvements are branched chain amino acids at high doses for sleep. And that's interesting because outside of tbi, high doses of branch chain amino acids may actually impair sleep because they compete for tryptophan uptake into the brain decreasing potentially decreasing serotonin melatonin production. But in TBI there are two studies that suggest improvements in sleep with high doses of branch chain amino acids.

Dr. Andrew Huberman

If somebody's going to take branch chain amino acids, presumably they're going to look at how much leucine is there for a variety of reasons. So do you recall how much leucine to get this effect post tbi?

Dr. Tommy Wood

So I, I don't think they, at least I don't remember the leucine dose but they were taking up to 60 grams of Branch Amy acids. 6060.

Dr. Andrew Huberman

Okay. Because a typical kind of suggested supplement bottle gym dose would be three to five grams. That's usually about three, six capsules.

Dr. Tommy Wood

Yeah. So okay, so like one study they did in veterans, they had, I think it was three doses of 20 grams spread across the day.

Dr. Andrew Huberman

Are you curious about these ibogaine studies that are looking at, you know, TBI and brain recovery? I mean ibogaine is a, it's a whole other thing because it's the most powerful long lasting psychedelic at least that I'm aware of. But it seems like there's, there's some interesting data coming out.

Dr. Tommy Wood

Absolutely. And then in people with a history of brain trauma and PTSD and I think some of these other psychedelics are going to be very interesting there as well. Potentially due to their neuroplastic effects that tend to particularly happen in macro doses, in the psychedelic doses. I think that there's a lot more to come there. But certainly the trials that have been done so far are quite compelling. But that's obviously in a very, very controlled kind of clinical.

Dr. Andrew Huberman

Yeah, the heart rate monitor. Again, it's not legal in the United States, although things, things are shifting.

Dr. Tommy Wood

But choline is another thing, particularly acetylcholine. So best evidence is for 1 to 2 grams a day of choline. Of choline, you know, in the form of cdp, choline or cytocholine, which is that, which is the same thing. Those are the main ones. Then there's some other, like NISHA supplements that do have some evidence. The one that's probably has the most evidence for it is Boswell. Boswellia, yeah, which is Indian frankincense. But there's an extract of Boswellia that's been tested in I think three different clinical trials after TBI showed some benefit. Enzogenol, which I think is a pine extract. Slightly less evidence than Boswellia. I typically would recommend people stick to the first group of kind of nutritional type supplements, but in very specific use cases based on specific symptoms, some of those other things might be beneficial. Then beyond that, we know that return to physical activity as soon as possible is really important without getting another head injury. Without getting another head injury. And so this really changed over the last few years, maybe five, ten years ago. People like rest is what you need to do. Go lie in a dark room if you've got a concussion. In sports, you would expect the team to have a rigorous return to play protocol that included low level, level aerobic activity. As soon as you're able to tolerate it two or three times a week at a level just below what might make your symptoms worse. And then first you do sort of like non specific aerobic exercise and then you start to bring back skill specific exercises, sports exercises, then go back into full training and then go back into, into playing kind of in that order. And that should be quite systematized now. So I would expect sports teams to kind of have, have that in place. So like the standard of care is generally physical therapy. If you have any ongoing cognitive or physical symptoms sort of a month plus after any kind of traumatic brain injury, there's some evidence that like virtual reality or augmented reality physical activity might improve cognitive symptoms. Vestibular therapy for balance and dizziness issues. And then then increasingly there's a focus on ocular motor training for convergence or other eye issues that are very common after concussions, but aren't picked up as often as people might like. But increasingly, eye tracking and these kinds of things are done particularly in professional sports or other arenas after brain injuries to kind of. Ideally you'd have a baseline, you figure out what's changed and then you would track that over time and you can, you can train that depending on the deficit.

Dr. Andrew Huberman

Those recommendations are going to be extremely helpful for people, athletes at all levels. I mean, I think for people that don't have access to the, you know, all the latest and greatest, you know, technology and coaches and nurses and doctors that, you know, there's a lot of head hits out there that aren't ne. You know, unfortunately aren't full blown brain bleeds and brain damage. But the, the low level trauma to the brain is obviously a consideration. Especially kids, like just falling off the monkey bars. Like parents want to know what they can do. So thank you very much for those recommendations. You're doing a strongman competition, all natural. This is not the enhanced games. No, just tell us what the format of that is. Well, first of all, how old are you?

Dr. Tommy Wood

You 41.

Podcast Narrator

Cool.

Dr. Andrew Huberman

Have you done one of these before?

Dr. Tommy Wood

Yeah, six or seven competitions at this point. I started during COVID I've done like a competition or two every year since then.

Podcast Narrator

You're a tall guy.

Dr. Andrew Huberman

You're like six two.

Dr. Tommy Wood

You weigh like 210, 215 usually.

Dr. Andrew Huberman

And is it. So it's height and weight class or just weight class?

Dr. Tommy Wood

So it's. It's weight class. I now. So now that I'm older than 40, I compete in the masters category. So there's a. This is one of my favorite things about strongman is that if you weigh less than £200, you're a lightweight. So I'm, I'm in the lightweight masters category. It means that I usually usually have to like do a water cut to like for a weigh in because I don't normally. I'm not. I'm normally above 200 pounds, but yeah, they, so they have, they have weight. They have weight classes and age classes.

Dr. Andrew Huberman

Can you eat your way and hydrate your way back up to after?

Dr. Tommy Wood

Oh, yeah. Like the. Usually weigh in 20 hours, 24 hours before. I'm. I'm definitely back to my usual weight by the, by the next day.

Podcast Narrator

Gotcha.

Dr. Andrew Huberman

Yeah, we don't want you trying to lift up heavy things. Dehydrated. What are the big events? Are you carrying stuff overhead? You're carrying stuff at your sides, you're.

Dr. Tommy Wood

What are you doing a standard Kind of local regional competition is five, is five events. I qualified for the natural World's Strongest man, which is going to be seven events. But there's usually some kind of deadlift, some kind of overhead pressing event, some kind of medley where you're like carrying something, lifting stones, farmers walks. So in truck pull, something like that. So like more dynamic. So there's like usually like a static max strength thing, but then also like more dynamic.

Dr. Andrew Huberman

The teeth, you do the teeth pull the.

Dr. Tommy Wood

Oh no, no teeth. No, no teeth pulling the. We didn't talk about oral health and cognitive function, but that's really important too. The events in the competition that I've got coming up, the, the World's strongest, there's going to be a farmer's walk. So that's where you just like pick things up at the side and kind

Dr. Andrew Huberman

of until first guy, let's say you, you hydrate Back to like 2 205, 210 or something like that. What, what, what's a good distance and weight to carry?

Dr. Tommy Wood

I know the weight in the competition it's 120 kilos per hand. So that's 264 pounds per hand. And as far as you can, as far as you can carry it.

Dr. Andrew Huberman

That's a big human in, in each hand.

Dr. Tommy Wood

Yeah. So typically, you know, if you, if you can get to where you've got like your body weight in each hand and you're able to pick it up and move with it even if it's not very far, I, I think that's pretty good. But like, you know, some people might say half your body weight. In reality, if you pick something up heavy and move with it, that's great. Like, and then get better.

Dr. Andrew Huberman

We're not talking about recommendations. This is your time to shine, my friend. People can work their way up. I, I, I watch Tom Havin's. Oh yeah, Instagram. We'll put a link to it. Everyone should see that his wife and his kid also work into the workouts. He's got a but man, he's strong. But yeah, carrying heavy weight. No, no, this is not your time to tell people people how to tiptoe into. That's a different podcast. So you're carrying £220 in each hand.

Dr. Tommy Wood

£264 per hand. And walking how far it's maximum distance in. I can't remember if it's 60 or 90.

Dr. Andrew Huberman

Can't set it down.

Dr. Tommy Wood

You can set it, you can set it down.

Dr. Andrew Huberman

Okay.

Dr. Tommy Wood

So as far as you can get in that period of Time and then be similar with it with a yoke walk. So there's a yoke where, you know, sort of like put it on Your back is £700. How far can you, how far can you walk in that period of time?

Dr. Andrew Huberman

This so primitive. Love it. Pure hypothalamic event.

Dr. Tommy Wood

Yeah. So in that event, in the, in the yoke walk, if you get to the end, I think it's 30, I think it's 30 meters, 90ish feet. If you can carry that in that far in the time cap, then you do reps on a circus dumbbell. So like this big massive dumbbell that you have like shoulder to overhead, there's one at £110 and the next is £135. Then there's going to be a loading medley. So sandbags and kegs like over a platform that, that's like, I think 200 to 300 pound implements. They kind of increase over time. There's a maximum squat and you have a choice of two different weights. And so like if you choose the bigger weight and you get reps on the bigger weight that you get a better score than somebody.

Dr. Andrew Huberman

Standard back squat, it's a.

Dr. Tommy Wood

Standard back squat is with an axle bar. So like a thick bar. And then in strongman when you have squatting, you usually have pads that you squat down to, so it's a specific height you squat down to to. So like that could give you an advantage if you're shorter. Right. Because you have to go less distance to get the weight on the pads.

Dr. Andrew Huberman

But like there's no geeking it and calling less than a one rep. No, people have done that. It doesn't look good.

Dr. Tommy Wood

Yeah, no, no. Like it just has to hit the pads and come back up. And the weights are 170 kilos and 200 kilos. So that's what, nearly 400 pounds and 440 pounds log press for reps. And again, it's a similar stock mile and I, I think it's 100 kilos, so 220 pounds and then 120, so 264. And then there's a sled like you, I think you push a sled and then you load it with a 275 pound sandbag and then you drag it in a time cap. I think that, I think that's all the events.

Dr. Andrew Huberman

Awesome. You'll let us know when it is?

Dr. Tommy Wood

Yes, it's at the end of August.

Podcast Narrator

Cool.

Dr. Andrew Huberman

Will it be on online?

Dr. Tommy Wood

It won't be online, but I'm sure there'll be some stuff on Instagram.

Dr. Andrew Huberman

Cool. I love that you do this. Clearly you got a lot of brains in that skull of yours and you're also super strong. Love hearing it. That's great. And you have no excuse not to carry the groceries at home. Right? So you lost that. Right. But there's no doubt you would anyway. That's awesome. I'm very impressed by people who continue to take on athletic challenges in their, in their adult life as, which is very appropriate to context today. So, Dr. Tommy Wood, thanks for coming out today. I learned a ton from you. And you know, going into this, I like, I like to think I know a thing or two about plasticity, having spent so much time in it and studying it over the years. But I learned a lot from you today and I know everyone else did as well. You're an exceptionally clear communicator and you're working on not just an important issue, you're working on the issue, this neuroplasticity thing and a whole lot more. So let's definitely get you back to talking about, talk about recovery from brain injury and stroke and things of that sort because there's a lot of additional things I think we could dig into. But meanwhile, you've given us a lot of actionable tools and yeah, I, I love that you're doing the Strongman competition. And come back again.

Podcast Narrator

We appreciate you.

Dr. Tommy Wood

I will. Thank you so much.

Dr. Andrew Huberman

Thank you.

Podcast Narrator

Thank you for joining me for Today's discussion with Dr. Tommy Wood. To learn more about his work and his book, please see the links in the show Notes caption if you're learning from and or enjoying this podcast, please subscribe to our YouTube channel. That's a terrific zero cost way to support us. In addition, please follow the podcast by clicking the follow button on both Spotify and Apple. And on both Spotify and Apple, you can leave us up to a five star review and you can now leave us comments at both Spotify and Apple. Please also check out the sponsors mentioned at the beginning and throughout today's episode. That's the best way to support this podcast. If you have questions for me or comments about the podcast, podcasts or guests or topics that you'd like me to consider for the Huberman Lab podcast, please put those in the comments section on YouTube. I do read all the comments. For those of you that haven't heard, I have a new book coming out. It's my very first book. It's entitled Protocols An Operating Manual for the Human Body. This is a book that I've been working on for more than five years and that's based on more than 30 years of research and experience and it covers protocols for everything from sleep to exercise exercise to stress control, protocols related to focus and motivation and of course I provide the scientific substantiation for the protocols that are included. The book is now available by pre sale@protographsbook.com there you can find links to various vendors. You can pick the one that you like best. Again, the book is called Protocols An Operating Manual for the Human Body. And if you're not already following me on social media I am Huberman Lab on all social media platforms. So that's Instagram X threads, Facebook and LinkedIn. And on all those platforms I discuss science and science related tools, some of which overlaps with the content of the Huberman Lab podcast, but much of which is distinct from the information on the Huberman Lab podcast. Again, it's Huberman Lab on all social media platforms and if you haven't already subscribed to our Neural Network newsletter, the Neural Network Newsletter is a zero cost monthly newsletter that includes podcast summaries as well as what we call protocols in the form of one to three page PDFs that cover everything from how to optimize your sleep, how to optimize dopamine, deliberate cold exposure. We have a foundational fitness protocol that covers cardiovascular training and resistance training. All of that is available completely zero cost.

Dr. Andrew Huberman

You Simply go to hubermanlab.com, go to

Podcast Narrator

the menu tab in the top right corner, scroll down to newsletter and enter your email. And I should emphasize that we do not share your email with anybody. Thank you once again for joining me for Today's discussion with Dr. Tom Brady Wood. And last but certainly not least, thank you for your interest in science.