The Brain Professor: "Popular Treat Now Considered Deadlier Than Smoking!", "Alcohol Is Shrinking Your Brain" - David Raichlen

As humans we have evolved to move, but why are we getting it wrong so often? David Raichlen is the Professor of Human and Evolutionary Biology at the University of Southern California. His research focuses on the connection between human evolution, physical activity, and health, examining why inactivity leads to so many chronic diseases in the modern world. In this conversation David and Steven discuss topics, such as how modern exercise levels compare to hunter-gatherers, the dangers of sitting, how air pollution is linked to dementia, and the misunderstanding of just how much exercise it takes to get health benefits. Follow David: Twitter - https://bit.ly/483oZIF Watch the episodes on Youtube - https://g2ul0.app.link/3kxINCANKsb My new book! 'The 33 Laws Of Business & Life' is out now - https://smarturl.it/DOACbook Follow me: https://beacons.ai/diaryofaceo Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  If you sit for 10 hours a day compared to nine hours a day, it's about a 10% increased risk of dementia. If you sit for 12 hours a day, it's about a 60% increased risk of dementia.

• 0:10Steven Bartlett?

  60%?

• 0:11Speaker 00

  Yes, so it's a problem that we have to deal with.

• 0:14Speaker 02

  David Reichlandt, professor of human evolutionary biology, exercise physiology and neuroscience at the University of Southern California.

• 0:22Speaker 00

  We are dealing with brain health problems that are only going to increase as our population ages. And healthy aging is linked to three behaviors: diet, physical activity and social connections. For example, people who have stronger social connections tend to have better brain outcomes than people who don't.

• 0:39Steven Bartlett?

  Does excessive alcohol use shrink the brain?

• 0:41Speaker 00

  Yes, over one drink per day is associated with negative health outcomes.

• 0:45Steven Bartlett?

  Sleep is the other one. That's a big factor in cognitive decline, right?

• 0:48Speaker 00

  It is. Less sleep and lots of sleep are both associated with higher risk.

• 0:53Steven Bartlett?

  Is there an optimal amount of exercise?

• 0:55Speaker 00

  Physical activity guidelines are 150 minutes per week, but only 25% of adults in the US meet those guidelines with older adults doing two to four minutes per day.

• 1:04Steven Bartlett?

  Two to four.

• 1:05Speaker 00

  But there are these small activities that provide big benefits, that generate new neurons and those neurons get integrated into key parts of the brain. Number one is...

• 1:16Speaker 03

  Remote work is dangerous.

• 1:17Steven Bartlett?

  Is there a natural for the human body?

• 1:19Speaker 03

  I'm concerned about physical health.

• 1:21Steven Bartlett?

  What's the practical advice to people that work at home that is realistic for us?

• 1:24Speaker 00

  If you combine [BLEEP] with [BLEEP], it will literally change your life.

• 1:38Steven Bartlett?

  David, if you had to summarize the essence of what your work shines a light on and what it intends to help us understand as human beings, how would you summarize that?

• 1:48Speaker 00

  What my work has been focused on is understanding how and why physical activity especially and lifestyle behaviors in general can impact health and most specifically, impact the health of our brains. And I think that, you know, we are dealing with...

• 2:10Speaker 00

  Brain health problems that are only going to increase as our population ages. So we have, we have six million people in the US today that are diagnosed with Alzheimer's disease or other related dementias. That's projected to grow to around 13 million people over the next 25 years or so. It's, we're projected to have 150 million people diagnosed with dementia worldwide over the next 30 years or so. So it's a problem that we have to deal with. And I, my work has been focused on ways that we can prevent these diseases that are associated with aging.

• 2:46Steven Bartlett?

  Why does the brain matter? And I say this in part because I think for most of my life, I just assumed, you know, I understand muscles, I can go to the gym and work on my muscles, but the brain, I just thought was this like piece of tofu in between my skull that I have very little control over.

• 3:01Speaker 00

  Yeah. I mean, I think that is, that was the prevailing view for a long time, that, you know, we grow our brains as children and during adolescence, and by the time you're in your twenties, your brain has done all the growing it's going to do, and now it's just this progressive shrinking over the rest of your life. And, you know, over the last few decades, we've realized that's not true, actually, that you can generate new neurons, especially in key areas of the brain, like the hippocampus that's associated with memory, and that that growth of new neurons may be the key to preventing or staving off these neurodegenerative diseases that have this big impact on the aging brain.

• 3:43Speaker 00

  And so, you know, if we can find ways to do that, and what I study is kind of doing that through physical activity and exercise, then we might be able to prevent some of the cognitive decline people experience with aging, maybe even stave off or prevent the development of Alzheimer's disease or other dementias.

• 4:02Steven Bartlett?

  What evidence have scientists got that we can actually grow?

• 4:07Steven Bartlett?

  Our brain.

• 4:08Speaker 00

  Well, that's a great question. The evidence in humans is a little trickier. So I can talk more about the evidence from animal models because with animal models, you can actually look inside the brain and see what's happening after, say, an exercise intervention. So there have now been many, many studies, especially in mice and rats, where researchers have shown that if you give them access to running wheels, or if you have them run on a treadmill, that you actually generate new neurons. And those neurons survive and get integrated into key parts of the brain. And we focus a lot on the hippocampus because it's so important to memory, which is a major aspect of being human, is being able to remember things.

• 4:51Speaker 00

  And researchers have shown very clearly that exercise and physical activity in these rodent models leads to the birth and survival of new neurons.

• 5:01Steven Bartlett?

  What is a neuron?

• 5:03Speaker 00

  A neuron is the main brain cell. So a neuron is sort of the main cell in your brain that's responsible for communication and transmission of information across brain regions.

• 5:15Steven Bartlett?

  And you said this hippocampus thing, which is where, I know you referenced that it's a sort of center point for memory.

• 5:20Speaker 00

  Yeah.

• 5:21Steven Bartlett?

  Where is that located in the head?

• 5:22Speaker 00

  So the hippocampus is in the temporal, deep in the temporal lobe of the brain. It looks like a seahorse, if you know, if it's kind of this curved, curved object in the brain that plays a big role in different aspects of memory. So it plays a big role, especially in working memory, which is keeping things in your memory over the short term that you may need to recall quickly. And it also plays a big role in the formation of memories of events that happen in your life, and also in spatial navigation, which is an important part of moving around in the world. So it's a really key part of the brain. And it's also one of the parts of the brain that is most affected by neurodegenerative diseases like Alzheimer's disease.

• 6:06Speaker 00

  So it is a part of the brain that deteriorates in these diseases, leading to memory deficits that have a big effect on your daily life.

• 6:16Steven Bartlett?

  Is that the only part of the brain that we're able to sort of regenerate? Or is it, can the rest of the, you know, I'm thinking about these rats and these mice. If we put them under a brain scan, would we see the mass of the brain increasing? And is it just that little seahorse hippocampus part, or is it the whole brain growing?

• 6:34Speaker 00

  So in rodent models where researchers have done sort of this detailed work, the hippocampus is mainly where new neurons have been found associated with exercise. In human studies, brain effects have been more widespread, so you do see volumetric changes in the hippocampus, but you also see volumetric changes or preservation of brain volume in frontal lobes, which are associated with executive cognitive functions. So things like planning and decision making.

• 7:06Steven Bartlett?

  Where do we need to begin to understand this relationship that humans have between exercise and their brains? There's got to be a point in history where exercise became, I guess, pro-survival in a way, where it became sort of imperative for us as a human species to do in order to preserve and extend our cognitive capacity, I guess?

• 7:29Speaker 00

  Yeah, I mean, all animals generally have to move to survive, right? They have to move to find food in some way. But at some point during human history, our pattern of movement shifted pretty dramatically, and we think that was around 2 million years ago. And at that point, we shifted from a more ape-like lifestyle to a hunting and gathering lifestyle, where our travel distances increased drastically. So we were moving over, you know, 20 kilometers sometimes per day, sometimes longer. And our intensity of movement probably shifted a bit to higher intensities. And so the need to be physically active changed.

• 8:12Speaker 00

  And if we think about the way that our physiology evolved, our physiology evolved in this context of Large levels of physical activity on a consistent basis. And so I like to think of that as sort of the normal condition for humans. And anything else, so as we kind of progress into modern times and many people have dropped their activity, that's actually the condition that is quite different from the way that our physiology functions best and from the way that our physiology evolved.

• 8:44Steven Bartlett?

  Does this mean that if I don't do physical activity, my brain will shrink?

• 8:50Speaker 00

  That's a good question. I mean, on a broad public health scale, yes, you know, low levels of physical activity or inactivity is associated with poorer brain health, smaller volumes of key brain structures, so smaller hippocampal volumes, for example, and worse cognition overall, and greater risk of dementia and Alzheimer's disease. On a personal level, it's hard to say specifically, right? Because there's so many factors that go into your risk of dealing with these conditions. But I can say that the best way for any individual to reduce their risk of cognitive decline is to be physically active.

• 9:30Steven Bartlett?

  What exactly is going on in my brain then when I'm physically active? That's causing my brain to be protected, insulated from things like Alzheimer's and dementia, and in some areas of the brain to actually grow. What is actually happening inside?

• 9:43Speaker 00

  A lot, a lot of fun things. So, I mean, one of the things that happens when we exercise is we increase blood flow to the brain. And that helps bring nutrients and keep our neurons functioning properly. But another thing that happens is that your muscles actually generate proteins called myokines. And those travel to the brain and they interact with neurons in ways that upregulate neurotrophins. So there's this great neurotrophin called brain-derived neurotrophic factor, BDNF. And BDNF acts kind of like a fertilizer for brain cells or for new neurons. So BDNF, when it's upregulated with exercise, helps both the birth of new neurons and it helps them to survive and integrate

• 10:27Speaker 00

  into the processes that they're meant to work for.

• 10:30Steven Bartlett?

  This suits probably a stupid question, but I'm just wondering why the brain just doesn't do that anyway.

• 10:34Speaker 00

  I know, wouldn't it be nice?

• 10:36Steven Bartlett?

  Wouldn't it be nice if it didn't have to exercise for the brain to restore itself in such a way?

• 10:41Speaker 00

  It would be nice in some ways, but that's just, that's not really the way that our physiology works, right? So, you know, as I was, as I was saying, if you think of the sort of natural condition of humans as being physically active, because that's what we had to do to find food and survive, then our physiology is adapted to that condition. And over the course of two million years, we never had to adapt to low levels of physical activity because it just wasn't a part of being human. And so it's only been in the last, you know, few hundred years that we've seen this rapid decline in activity. And that's just not enough time to see that sort of adaptation occur.

• 11:24Steven Bartlett?

  What happened a couple of hundred years ago that caused this decline in physical activity? Was there like a certain invention or something? Was there a change in cultural understanding?

• 11:33Speaker 00

  I mean, I think things start with the Industrial Revolution.

• 11:35Steven Bartlett?

  Okay.

• 11:36Speaker 00

  As we, as we mechanize and we find ways to, to reduce our, the need to be physically active, to gain access to food, to survive. And then as, as we move on, you know, in the last 50, 60, 70 years, we start to see a lot more office jobs, right? We start to see changes in our work life that reduce activity patterns throughout the day.

• 12:02Steven Bartlett?

  Cars, I guess.

• 12:03Speaker 00

  Cars, so in terms of commuting, leisure time, what do we, what do most people do during their leisure time? The couch is really comfortable. Our screens are really enticing, TV screens, but now phone and computer and all these things. And so we end, we end up sitting a lot.

• 12:22Steven Bartlett?

  Do you have the stats on the increase in sedentary behavior? That is basically people being still.

• 12:28Speaker 00

  It's hard in terms of increase because we, we haven't measured time spent sitting for very long. That's really been a pretty recent part of research. But we do know that today people are sitting for on average nine to 10 hours per day. And that level of sitting is also linked with really low levels of then being physically active. So we can think about, you know, how many of us are actually? Active enough to meet the kinds of guidelines that are prescribed for health. And we're talking about 25% of US adults actually meeting those guidelines. And that number hasn't changed in 20 years or so. Even with all the messaging, physical activity is good for you. You need to be more active.

• 13:13Speaker 00

  You need to exercise. You know, people just don't do it.

• 13:17Steven Bartlett?

  I guess the very heart of this is this idea when we're talking about the brain not just taking care of itself without physical activity is this notion that all parts of our body and all parts of our being are created in response, pretty much, or at least develop in response to an external stimuli of some sort. So like me going to the gym, the example I gave earlier, if I pick up the weight, then the muscle grows. And whenever I try and implement a very sudden behavioral change, like when I suddenly started training football four times a week, my muscles basically exploded in my feet because they just weren't strong enough to deal with that demand. And I guess the same applies to the brain, that if we don't use it, we lose it, basically.

• 13:59Speaker 00

  Yeah, I mean, our bodies are fantastic at tuning what we put energy into to maintain to the kinds of activities that we're engaged in, right? And so, you know, I like to think of our bodies as great energy minimizers in some ways that, you know, if you're not using muscles, those muscles will get smaller because it takes energy to maintain that tissue. If you're not, you know, creating the need for your heart to pump blood across your body by exercising, you'll atrophy some of that tissue, you'll reduce blood vessels, your heart will become less efficient because you've signaled to your body that you don't need that energy to be put into that tissue maintenance.

• 14:41Speaker 00

  The same, it seems, holds true for the brain, that if you're not active in some way, then you're kind of signaling that you don't need some of that energy to be put into that tissue.

• 14:52Steven Bartlett?

  Is all activity the same? So if I'm doing strength training. Is that as beneficial for my brain as potentially going for a run outdoors?

• 15:01Speaker 00

  That's a great question. And you know, we, there is not a ton of very clear work that's compared directly different types of activity in ways where I could tell you for sure, this is the best one. Right. There are data that suggests that resistance training is beneficial to the brain. There's more work on endurance activity. And I actually think that's probably because it's easier to do rodent work on endurance activity than resistance. And so trying to translate across those models is a little bit easier. Both forms of exercise have benefits. They may be through different pathways. There may be different biological mechanisms that are underlying those benefits. I've kind of seen some cool work coming out lately that has tried to look at,

• 15:45Speaker 00

  for example, different types of endurance exercise. So there's a great study that came out. Are you familiar with orienteering? It's a sport where you're given like a map and a compass, and you have to find your way across a route as fast as possible. So it kind of mixes endurance activity with spatial navigation and, and moving around your environment and figuring out where you are.

• 16:08Steven Bartlett?

  Typically done outside, right?

• 16:09Speaker 00

  Oh, yeah, always done outside. Typically done on natural, like on trails and things, but people do do it in cities as well.

• 16:16Steven Bartlett?

  Okay. So like, and this is over miles and kilometers?

• 16:19Speaker 00

  Yeah, this would be like, like a trail run, kind of, or something like that. And there's a great study that just came out looking at, it was a randomized control trial. So they actually randomized people into either an orienteering group, or a hiking group, or a control group. And over a couple of months, they found that the orienteering group actually had better performance on cognitive tests, like memory tests and executive function tests than even the hiking group. Both of those groups did better than the control group, but there was actually this extra boost if they, for the people who were in the orienteering group. So we're starting to see that maybe some different activities could potentially enhance the effects of exercise on the brain.

• 17:00Steven Bartlett?

  What's the conclusion there? What does that study hint at in terms of, because hiking, you're out in nature, you're navigating your way up a hill or something. Orienteering? That it's it's almost like solving a puzzle, right? Because you've got a map and a compass.

• 17:14Speaker 00

  Yeah, I mean, I think it it fits into an evolutionary model, at least in my mind, where the purpose of being physically active is to move around a habitat to find things, find food, find water, find firewood. And so, physical activity in in this sort of ecologically relevant world is a combination of cognitive challenges and physical challenges. So I think that when you combine them in the way that perhaps orienteering does, or maybe some other sports, you might actually get a bigger boost for your buck, a bigger bang for your buck, in terms of the brain benefits. And that, I think, is rooted in our evolutionary history.

• 17:56Speaker 00

  Like I said, I think that being active in an evolutionary sense always comes with sort of a cognitive challenge. Nobody's ever just going out for a workout. There's no reason to. If you're not, if you don't need to find something, you're going to relax and rest because you're an energy minimizer, right? Don't spend that energy if you don't have to.

• 18:14Steven Bartlett?

  Is there any animal studies that show how have doing challenging exercise, so cognitively challenging exercise, so exercise that involves problem solving, improves our neuroplasticity or increases our the amount of brain cells we have across our brain?

• 18:28Speaker 00

  Yes, yeah, there there have been. And a great impetus for our work was some of the work done in rodent studies by a professor named Gerd Kemperman. And he and his group did some work in in mouse models where they combined access to running wheels with a very enriched cage environment. So they looked at, they they did a very careful study where they looked at some mice who were just living in their cage, you know, normally a control group. They looked at mice that were given access to a running wheel. They looked at mice that were given access to this enriched environment that's cognitively challenging and things to play on. And then they looked at a combined group where they combined the running wheel with the enriched environment.

• 19:12Speaker 00

  And they found this effect where the combined environment doubled the growth and survival of new neurons compared to either. Wheel running alone or Cajun Richmond alone. So you got this really cool additive effect where you really enhance the effects of either one of those behaviors by combining them.

• 19:33Steven Bartlett?

  If we can pull that conclusion over to human life, if we can, if one assumes that the same effect will be seen in humans, what does that then tell us we should be doing? If we, if our objective is to live long, happy, healthy lives with fantastic brains, what should we then be doing exercise wise?

• 19:51Speaker 00

  Well, I think number one is just getting active, right? So I think, you know, to me, the number one recommendation is, you know, to be physically active and especially for people who aren't that active right now, the best thing they can do is get out and start walking. But if we want to enhance the effects of physical activity on the brain and build on this animal work, we're starting to see some good evidence that if you do something similar, if you combine physical activity with cognitive challenges, you can boost the effects of physical activity on, on the brain, on especially cognitive performance. And so, you know, most of the work has been in controlled environments. So we've done a study where we built a game that you can play while you're on an exercise

• 20:36Speaker 00

  machine. So you combine exercise with challenging activities, right? And we've shown that you can actually get a bigger benefit for cognition when you do that than when you just exercise or you just play a game. And so we can, you know, take that and perhaps translate that into the real world and think about ways that you can make your exercise more cognitively challenging. So can you go out and challenge yourself spatially? Take new routes, right? Oftentimes, especially runners or walkers, they just do the same route every time or the same, they have two or three routes that they do every time, depending on how long they want to go. But maybe we should be challenging ourselves a little more, right? Maybe we should take new routes where you get a little lost and then have to find your way back, right?

• 21:21Steven Bartlett?

  I'm someone that runs on the treadmill, but Jack over there, he runs outdoors. So you're telling me sort of top line that Jack is serving his brain more than I am when I'm just on that same treadmill every day in my hotel room while I'm out here in New York, whereas he's running around Central Park?

• 21:37Speaker 00

  It's possible. So I think there's, there's a couple of things. You know, running on a treadmill may end up being a little more like running on a running wheel for a mouse without the extra enrichment. And yeah, running outside may provide some of those better benefits. We also know that running outside actually has a lot more benefits than just maybe cognition, but also seems to boost mood a little bit more than running or exercising in more impoverished environments, you know.

• 22:06Steven Bartlett?

  Really?

• 22:07Speaker 00

  Yes. So there's like, there's a research movement called the green exercise movement that is focused on the impact of exercising in green spaces versus more urban environments or indoors on exercise equipment. And I don't want to scare anybody.

• 22:24Steven Bartlett?

  No, no, no.

• 22:25Speaker 00

  Like I said, exercise is great. If, if you, if running on a treadmill works for someone's lifestyle, it is fantastic exercise.

• 22:32Steven Bartlett?

  But you know what I mean? I could go outside.

• 22:34Speaker 00

  Yeah.

• 22:34Steven Bartlett?

  So the only reason I'm not is because I don't know the difference.

• 22:38Speaker 00

  Right.

• 22:38Steven Bartlett?

  So, you know, it's for, for someone like me, of course I could have gone outside this morning instead of just being on the treadmill. But I've, I did, I thought they were the same.

• 22:46Speaker 00

  Right.

• 22:47Steven Bartlett?

  So you're telling me that there is potentially some upside, according to research, in me getting outside and running in both mood and neuroplasticity makes me go, okay, tomorrow I'll make a different decision.

• 22:56Speaker 00

  Absolutely. I think that, I mean, to me, that's the really surprising outcome of a lot of this research is that moving outside and especially moving in green spaces, so moving in parks or near parks or moving on trails, things like that, seems to have bigger benefits, especially for mood. We don't know yet about the cognitive benefits. That's our hypothesis. But certainly some of the research out there suggests that for mood and feelings of well-being, moving your body in a green space provides a little bit extra benefit than moving in, in, like I said, in city streets or in, in indoors.

• 23:33Steven Bartlett?

  One of the things I'd, I notice all the time is if I exercise before I do this podcast, my brain just seems to work.

• 23:39Speaker 00

  Yeah.

• 23:39Steven Bartlett?

  Whereas if I get out of bed. And I don't exercise and then I come and do this podcast. It's like the words just don't go from my brain to my mouth properly.

• 23:47Speaker 00

  Yeah, I mean, that's why I got into this, right? Because I started noticing the same thing. And I started noticing how much better I felt after I exercised. And, you know, and to this day, right? I mean, my wife knows when I didn't go for a run in the morning. I'm not that pleasant of a person to be around the rest of the day.

• 24:04Steven Bartlett?

  What is going on there? Do you know the sort of physiological reason why it feels like if I exercise in the morning before I have a two hour conversation, my brain and mouth seem to be connected?

• 24:14Speaker 00

  One of the things that I think is happening is that you've activated reward centers in your brain that have increased your arousal, right? They've activated these centers in your brain that are making you feel good. And when we feel good, we feel more confident. We're not as sort of stuck in our heads. We're not as, we're more present. But I think that is rooted in the rewarding sensations of exercise, right? It makes us feel better. And when you feel better, you function better across all aspects of your body, of your life. And those rewards are molecular rewards that are popping up. There's similarities with how people feel when they use certain drugs.

• 24:57Speaker 00

  They're activating similar receptors in your brain is when you're using certain drugs, although to a much lower extent. And it's really, it's making you sharper and making you more confident and making you feel better.

• 25:09Steven Bartlett?

  Is there an optimal time of day to exercise? I know to your point about any exercise is better than no exercise. But is there an optimal time to exercise? I mean, when do you exercise and why?

• 25:20Speaker 00

  Well, I exercise first thing in the morning.

• 25:21Steven Bartlett?

  Why?

• 25:22Speaker 00

  Because I will feel better all day, right? And so, I mean, there's two reasons. I think, one, if I save exercise for later in the day, there's a greater chance that things will come up and I'll, you know, I'll find excuses not to. But mainly it's because first thing in the morning, if I exercise, my whole day is better. Right? And so that's the motivation to get out of bed for me and get out the door is I literally think about how I will feel if I don't do it. Because sometimes it's cold, sometimes you don't, it's dark, you know, this time of year, you don't want to do it. But if I think about how I'll feel the rest of the day, that's a big motivator.

• 25:59Steven Bartlett?

  And people might hear this and they might be starting from zero, right?

• 26:02Speaker 00

  Yeah.

• 26:02Steven Bartlett?

  They might not be exercising at all. What would you say to those people?

• 26:06Speaker 00

  Not to be intimidated by the advice out there about how much you have to exercise, because it's actually surprising how little you need to exercise to gain benefits. So if you're starting from zero, the biggest bang for your buck from a public health standpoint are people who are starting from almost zero and just starting to exercise a little bit, right? Just getting out the door and taking a thousand steps, right? Something like that. You know, those, those sorts of small amounts going from zero to two, three, four thousand steps per day of exercise, that's, that's the biggest public health benefit. Then you start to see diminishing returns, right?

• 26:48Speaker 00

  So if you're, if you're already exercising a lot and you, and you want to bump it up a little higher, you know, the amount of benefit you get is, is smaller than going from very little to, to more. But I think that's the, I mean, that's the surprising thing for me is that, you know, if you, if you are not an exerciser, getting four or five thousand steps per day is going to give you a big cardiovascular benefit and a big benefit for your brain.

• 27:13Steven Bartlett?

  You've studied some of the tribes around the world, so the Hadza tribe, right?

• 27:16Speaker 00

  Correct, yes.

• 27:18Steven Bartlett?

  What, what work have you done with them and when did that research begin?

• 27:22Speaker 00

  So I started working with the Hadza in 2009. That was my first time out there. And we've been working with them and interested in what kinds of health impacts you see in a, in the context of a hunting and gathering lifestyle.

• 27:39Steven Bartlett?

  And they live in what part of the world?

• 27:40Speaker 00

  So they live in northern Tanzania.

• 27:42Steven Bartlett?

  Why did you want to spend time with them?

• 27:44Speaker 00

  So the Hadza provide a window into what a hunting and gathering lifestyle looks like. And so if you work with individuals who are still pretty much full-time hunting and gathering, they give you a view of how much physical activity does it take to be a hunter-gatherer, for example? And how does that relate to biomarkers of cardiovascular health? Or how does that relate to their cognition? How does this lifestyle impact the way that they age? And the Hadza give us this really important view of what that lifestyle is like in terms of behavior and activity and, and aging.

• 28:23Steven Bartlett?

  Is there a optimal amount of exercise that's in line with our evolutionary past? We said that we've evolved to be active. Is there like an average amount? Do we see this in the Hadza tribes? Do we have any clues from history?

• 28:38Speaker 00

  Yeah, I mean, so we can look at what living hunter-gatherers do, and that provides us with a clue as to what that lifestyle might entail. And I do like to think about things in terms of steps per day often, because that's an easy metric for people to understand and track for themselves. There are more complicated ways to measure physical activity, but steps is a good one, step counts. And so the Hadza, as we've measured their step counts, are getting a lot. So it's like 15,000 to 20,000 steps per day in that range, which is quite a bit of movement. And that's not to say that that is the optimal amount, but that's what we see in hunting and gathering lifestyles. The benefits that we get from a public health standpoint

• 29:21Speaker 00

  start to occur at much smaller levels. So 4, 5, 6,000 steps per day, you start to see some real benefits. And as I said, you start to maybe see diminishing returns as you get higher and higher levels. So what we see in the past or see in living hunter-gatherers may be quite different than what's necessarily optimal for our health in terms of where are we going to get the most benefit? And where do we start to trail off?

• 29:48Steven Bartlett?

  With the Hadza, is that across all age groups?

• 29:51Speaker 00

  So, I mean, there is a decline in physical activity with age. That's clear. But even older adults, we've measured physical activity in adults in their 70s and even their early 80s, and they're still far exceeding what we do in the US or the UK.

• 30:10Steven Bartlett?

  By a factor of?

• 30:12Speaker 00

  A lot of times, the way that we measure physical activity is in terms of how much time they spend in moderate or vigorous intensity activity. So these are activities that get your heart rate up up to about 50, 55% plus of your maximum heart rate. And older adults are still engaging in 60, 70, 80 minutes per day of that kind of activity. Whereas, say, in the US, you might see older adults, on average... Engaging in two to four minutes per day of that level of activity.

• 30:44Steven Bartlett?

  Two to four.

• 30:45Speaker 00

  Yeah, so on average, right, for older adults. So we just don't see as much physical activity in the US. Like I said before, only 25% of adults in the US meet physical activity guidelines. And physical activity guidelines here are 150 minutes per week of moderate to vigorous physical activity. So in the US, 25% of adults meet those guidelines. In the HADSA, those that we have measured are meeting weekly physical activity guidelines on average in two days. So they're getting 300 minutes of physical activity in a couple of days versus, you know, adults in the US who aren't coming close to that.

• 31:27Steven Bartlett?

  One of the biggest killers, I think maybe the biggest killer of people in the US, and I believe in the UK as well, is cardiovascular diseases.

• 31:34Speaker 00

  Yeah.

• 31:34Steven Bartlett?

  Is, am I right in thinking that is the single biggest, that's the disease you're most likely to die from?

• 31:39Speaker 00

  Yes, I believe so.

• 31:40Steven Bartlett?

  When we look at the HADSA, how are they doing in terms of cardiovascular illness?

• 31:44Speaker 00

  So we don't see a lot of evidence of disease risk. So we have not yet measured cardiovascular outcomes, like we haven't measured mortality, for example, from cardiovascular disease. But we have measured biomarkers, so things like cholesterol levels, triglyceride levels, blood pressure, so looked at whether there's hypertension. And we see very little evidence of cardiovascular disease in this group. Others, other researchers have looked at other groups. So there's a long-term study of a group in South America called the Chimene that have been studied in a lot of detail. And there, they found almost no evidence of cardiovascular disease. And they've been able to look in a much more detailed way at outcomes like, you know,

• 32:29Speaker 00

  death from cardiovascular disease. And they see almost no evidence of high levels of cardiovascular disease.

• 32:35Steven Bartlett?

  Diabetes.

• 32:36Speaker 00

  Very little evidence of diabetes, very little evidence of dementia. I mean, these diseases that we look at as inevitable parts of aging, they're just not, right? They are not inevitable. A lot of them are a product of our lifestyle. And you know, I'm most familiar with dementia, and something like 40% of risk of dementia is preventable. It's due to lifestyle. Right? We have the ability to modify our risk in really big ways by altering the way we live.

• 33:07Steven Bartlett?

  What else has inspired you or caused you to implement behavioral changes into your life, new habits, based on your work researching the Hadza tribe? Is there anything at all that has either changed your mind or modified how you live your life?

• 33:21Speaker 00

  Yeah, I mean, I think a couple of things. Number one, physical activity is sort of the cornerstone of my life. That's sort of, that is, that is, that's been driven by my personal sort of enjoyment of it. But also, from a research standpoint, that's been really motivating to maintain an active lifestyle across these years. But more recently, I've been really interested in sitting, which is, you know, in some ways, it's not really the opposite of being physically active, but it's another behavior that we engage in actually for much more time per day than anybody's physically active. And we've done a lot of work on resting behaviors in the Hadza.

• 34:04Speaker 00

  And that's been an area that I've sort of tried to pull into my life as well, is trying to understand, you know, how sitting can impact our lives? And then how our evolutionary biology may be tweaked by this behavior. And so I've tried to implement some things like trying not to sit too long, trying to break up my sitting, finding ways to not be stuck in a chair all day. And a lot of that's driven by my research.

• 34:35Steven Bartlett?

  What's the issue with sitting?

• 34:36Speaker 00

  So sitting is, sitting's a beautiful thing, right? I mean, we're doing it right now. It's really comfortable. And the reason it's comfortable is because we've basically taken all of the load off of our lower body. So we're supporting ourselves in these chairs, right? You gotta move around.

• 34:51Steven Bartlett?

  Suddenly you mention it.

• 34:52Speaker 00

  When I give talks about sitting, all of a sudden I start seeing people fidgeting, right? Some people get up and stand up in the back. So, you know, you take the load off of your lower legs and your muscles don't have to work. And, you know, not surprisingly, that's super comfortable. We're not working hard. But at the same time, what's happening is The, our muscles not being active means that what we normally do to fuel muscle activity, which is, you know, we break up triglycerides in our bloodstream and that's, you know, that's, those are broken up into fatty acids that fuel muscle activity. That's not happening. And so those, those fuels now build up in our, in our blood vessels and that's associated with cardiovascular disease. So sitting for long periods of time is associated with some

• 35:37Speaker 00

  negative health outcomes. And one of the things that we've learned from working with the Hadza is that, you know, people rest a lot. Like the Hadza, they sit for as, or rest and sit for as long as we do, which was actually super surprising to us. We thought that wouldn't be the case. We thought they were going to be active, you know, all the time and there would be much less sitting. But when we finally actually measured it with accelerometers, they're resting for the same amount of time that we are. But they're not sitting in chairs. They're resting in postures that require a little muscle activity. So they're squatting, or they're, they're kneeling, or they're sitting on the ground in ways that, you know, you have to kind of keep shifting your body around. And it's possible that just that kind of low level of muscle activity is, is how

• 36:22Speaker 00

  our bodies are well adapted to rest. And what's weird is the invention of chairs. And what's weird is the invention of these objects that completely eliminate the need for our lower bodies to use muscle activity.

• 36:34Steven Bartlett?

  Chairs are a fairly new invention. When, when did chairs come into the picture?

• 36:37Speaker 00

  The first chairs that we know about from the archaeological record are about 5,000 years old. But, you know, the ubiquitous use of chairs is, is probably even more recent than that, right? Chairs are, chairs are these weird objects that they're not only, you know, ergonomic and, and made for, you know, our comfort, but they also over history have had implications for economic status and power and, you know, taking a seat at the table and a throne in, in, you know, in, in terms of political power. Where you sit has always been important from a political and economic and social standpoint. So chairs have, have sort of taken on a big part of our lives. And if you, you know, if you walk

• 37:19Speaker 00

  into someone's house, you know, generally the first thing that you're seeing is their seating environment, right? Chairs and couches and, and, and places to sit are

• 37:31Speaker 00

  Part of the way we design our world, we don't think about them that often, but we use them more than almost any other object in our lives.

• 37:39Steven Bartlett?

  Kind of like we assume they've just always been a thing. It's most of these things in our life, we assume that this is just the way it's always been. And this is therefore normal and acceptable. But it must be pretty illuminating to go and see these tribes who, they must think we're crazy. They must think we're so strange by the things that we do.

• 37:55Speaker 00

  I mean, they do, but at the same time, you know, when we work in in Hadza Land, we bring chairs because they're comfortable. And, you know, the the first thing that happens when we're out there is, you know, this crazy game of musical chairs that if one of us gets up, you know, someone comes over and sits in our chair. And why is that? Because they're super comfortable. And so I don't think they they necessarily think we're crazy. I think they they, you know, they enjoy sitting in the chairs. They just don't have them.

• 38:22Steven Bartlett?

  Be careful not to leave any of them there.

• 38:24Speaker 00

  Well, that's what, you know, that's what happens is, you know, we'll go out for the day and and go, you know, go, you know, foraging with people and and come back and, you know, you can't find, you want to sit down and you can't find a chair because everyone's sitting in your chair. But that's totally fine. They they deserve to rest just as much or more than than anybody else.

• 38:42Steven Bartlett?

  What's the practical advice, do you think, there for for employers, for people that work at home, for people that sit in chairs often? Because we, people can't just, we can't just do this podcast squatting.

• 38:52Speaker 00

  Right.

• 38:52Steven Bartlett?

  Well, we could, but you know what I'm saying?

• 38:54Speaker 00

  It'd be very challenging.

• 38:55Steven Bartlett?

  It'd be very, very challenging. Is there some kind of middle ground that is accessible and realistic for us?

• 39:00Speaker 00

  Yeah, I think the I think the best thing people can do is just try not to sit for prolonged periods of time. I mean, there's no way to eliminate sitting. And I don't think that standing all day is is necessarily the answer. I don't think that that's necessarily a benefit full time. I think breaking up sitting into smaller periods is probably the best thing we can do. So, you know, one of the pieces of advice is is actually that I always tell people is, you know, just drink more water. So you got to get up and pee more. That is, that's an easy way to to kind of force yourself not to sit for two hours at a time. But, you know, having those kinds of reminders that you should get up, move around. There's been this popular notion of take And exercise snack break. So, you know, every 30 minutes, every 45 minutes,

• 39:46Speaker 00

  get up and walk up a staircase or do some pushups or something just to get your body moving, get your muscles working, do some squats. And so that can be, you know, really beneficial.

• 39:56Steven Bartlett?

  Some people will hear that and go, yeah, but if just doing, just getting up and doing a two minute walk, how's that going to help?

• 40:01Speaker 00

  Yeah.

• 40:02Steven Bartlett?

  In the grand scheme of things.

• 40:03Speaker 00

  There's really good evidence. So, okay, a couple of things. From an epidemiological standpoint, there's been this really great work coming out on something that's called vigorous intermittent physical activity. So this is activity that's not purposeful. It's short in duration, but it's vigorous. So going up the stairs or walking really briskly for like a minute or two. That in the long run, people that do that often have a lower risk of mortality and a lower risk of cardiovascular disease, regardless of purposeful physical activity, right? So you can actually get big benefits by just doing these short bursts of activity.

• 40:41Steven Bartlett?

  Walking to get your lunch or?

• 40:43Speaker 00

  At a vigorous pace.

• 40:44Steven Bartlett?

  At a vigorous pace.

• 40:45Speaker 00

  Right. Yeah. I mean, walking to get your lunch is great, but you get a little bit more benefit from doing it at a vigorous pace. So, you know, if you're walking and you can't sing at the same time, or you can't talk at the same time, that's, that's now you're getting into kind of a vigorous intensity. And there's also been randomized controlled trials where people have actually in the lab, had people sit for, you know, eight hours, not do anything. And then they've taken those same people on another day and had them sit, but break it up into, you know, 20 minutes, break it up and walk on a treadmill for two minutes, something like that. And those studies have shown changes in cardiometabolic markers. So they've shown, shown changes in insulin levels and changes in

• 41:29Speaker 00

  in triglyceride levels and cardiovascular disease biomarkers, just from breaking up your sitting into, into shorter periods. So you really can have a profound effect, I think, on your health by implementing some of these small changes.

• 41:44Steven Bartlett?

  Is there, you know, a type of exercise? We touched on this a little bit earlier on, but I'm really trying to make a case to myself that I should be doing more aerobic exercise. Then I typically do a little bit of aerobic exercise unless I'm training for something in particular and a lot of sort of resistance training. Is there any case that I should be doing more aerobic exercise or resistance training if my goal is to improve my brain, my memory, my cognition?

• 42:12Speaker 00

  I think, I mean, I think both are important. From, from my perspective, aerobic activity, you know, we're, we're thinking about this from an evolutionary standpoint, right? We've been talking about this idea of can we boost the effects of exercise by adding cognitive challenges, right? And so from my perspective, aerobic activity is probably the place where you can do that in the easiest way. So by moving yourself outside in new environments, by adding in some, some spatial navigation challenges to a workout, you might be able to do that a little easier than, than when you're lifting weights.

• 42:46Steven Bartlett?

  You know, this whole brain training industry that emerged, I think it emerged like 10 years ago and there became all of these apps that were kind of like puzzles and stuff. And they claimed that if you use these apps and do this brain training stuff, then it will make your memory better, your IQ higher, all of these things. Is there any merit to these brain training games?

• 43:05Speaker 00

  There does appear to be some. So there do appear to be some training games that, that do improve aspects of, of cognition. You know, it's been a, it's been a tough industry because not all of the studies are super high quality and, and some of the claims can be a little bit further ahead of maybe where the science is. So are the effects that big? Like if you do it, you know, every day and you invest all this time, are you going to get the biggest effect? But there does appear to be some benefit. You know, if I were in a perfect world, would I be doing everything I could to stave off the potential for developing dementia? Yes. And so if there's a little bit of evidence that that could be helpful, I would, I would

• 43:49Speaker 00

  definitely jump in and do it.

• 43:51Steven Bartlett?

  Just learning generally?

• 43:53Speaker 00

  Yeah, learning, so learning.

• 43:56Speaker 00

  Education, keeping yourself cognitively challenged throughout your lifespan is clearly a way to keep staving off cognitive decline.

• 44:07Steven Bartlett?

  Is there research to support the idea that learning or reading or some kind of education?

• 44:11Speaker 00

  Yes, for sure, for sure. And, you know, education is a difficult one because education is wrapped up in a lot of other things, right? So, education is wrapped up in your parents and socioeconomic class. And so, when we study education from an epidemiological standpoint, it's really hard to deal with the kinds of other variables that could confound those relationships. But certainly lifelong learning seems to be associated with better reserve. So, one of the things that we think about in terms of cognitive aging is how much reserve do you build up over the course of your lifespan so that as we undergo some atrophy and decline, which is kind of inevitable, have you built up enough reserve so that that decline doesn't impact your daily life, right?

• 44:55Speaker 00

  You have enough of this built up tissue and built up reserve and built up connections that even if you undergo some decline in tissue, it doesn't impact you.

• 45:05Steven Bartlett?

  Reserve being kind of like pathways, is that?

• 45:08Speaker 00

  Reserve could be pathways.

• 45:10Steven Bartlett?

  Right.

• 45:11Speaker 00

  It could be volume.

• 45:12Steven Bartlett?

  Volume.

• 45:13Speaker 00

  So, it could be a bigger hippocampus.

• 45:14Steven Bartlett?

  Okay.

• 45:15Speaker 00

  Or it could be the connections between your hippocampus and other parts of the brain. And both of those are important. And you can build those up across your lifespan with physical activity, with cognitive engagement, things like that, and with avoiding some of the sort of negative health behavior like smoking or excessive alcohol use.

• 45:35Steven Bartlett?

  Does excessive alcohol use and smoking shrink the brain?

• 45:38Speaker 00

  They do. They are risk factors in cognitive decline and the development of dementia and Alzheimer's disease.

• 45:45Steven Bartlett?

  How much alcohol?

• 45:46Speaker 00

  We know that excessive, like, you know, excessive consumption over the sort of one drink per day or two drinks per day for a man, one drink per day for a woman.

• 45:56Speaker 00

  That level of alcohol consumption is associated with negative health outcomes, including risk of dementia and Alzheimer's disease.

• 46:04Steven Bartlett?

  So, sleep is the other one that's a big factor in cognitive decline, right?

• 46:09Speaker 00

  It is. And sleeps, I mean, a lot of things happen during sleep that are really important. One of the things that happens during sleep, we think, is that it's a time where your brain is clearing these plaques that can build up, that are associated with neurodegenerative disease. And so if that's the case, and there's been some evidence that suggests that sleep is when some of that clearance is happening, then poor sleep quality just doesn't allow that function to occur. It allows those plaques to build up. Sleep is weird in some ways because it's not always more is better. So it follows a U-shaped curve in terms of risk

• 46:49Speaker 00

  of developing dementia, for example, where less sleep and lots of sleep are both associated with higher risk. And there's like a sweet spot, right? There's a sweet spot of, you know, call it seven to nine hours a night, something like that, that is where your lowest risk is going to be.

• 47:08Steven Bartlett?

  So you can oversleep?

• 47:09Speaker 00

  You can. Here's the caveat to that is what's going on with oversleepers that you're not able to suss out in your analysis. So a lot of times, people oversleep because they're depressed. And we know depression is linked with these neurodegenerative diseases. And so it's possible that it's those, it's not the actual sleep itself, but it's what's linked with too much sleep.

• 47:34Steven Bartlett?

  Like inactivity. They might not be exercising as much as other groups.

• 47:37Speaker 00

  Yeah. What are you displacing? So another, yeah, that's a great point. Another thing that we can look at is, you know, you have 24 hours in a day, right? And so if you sit for an extra hour, that's going to come at the expense of something else. If you sleep for an extra hour, yeah, or exercise, or light physical activity, just housework or something. So you can't, the day is not infinite. So anything that you choose to do is displacing something else.

• 48:05Steven Bartlett?

  What about having friends?

• 48:06Speaker 00

  Yeah.

• 48:07Steven Bartlett?

  Having a partner, you know, does that, is that going to increase my chances of having a great cognitive function and a big brain?

• 48:13Speaker 00

  Well, it depends on how good your relationship is. So, I mean, just having a partner, sometimes, you know, if it's, if it's, there are ways that that can be associated with negative outcomes if, if your relationship is

• 48:24Steven Bartlett?

  Tell me about it.

• 48:25Speaker 00

  is challenging, right? But, you know, so I, I think of healthy aging as linked to really three main behaviors. Diet, physical activity, and social connections. Okay? Social connections are key. And so, you know, we're, we're hearing now, there's a kind of a buzzword, the epidemic of loneliness, especially coming out of the pandemic years, that is really, it's kind of frightening because people have gotten more used to sort of living alone and being alone. And those social connections are a key aspect of maintaining a healthy brain when we age. We know that.

• 49:01Steven Bartlett?

  How do we know?

• 49:03Speaker 00

  Well, mainly from epidemiology. There's two ways to, two ways to analyze these, these, these questions. There are randomized control trials and sort of observational trials. It's really hard to do randomized control trials on loneliness and, and look at long term outcomes. So we look at observational data and people who have stronger social connections, who have, it's not necessarily more, but it's, it's higher quality social connections who, you know, if you ask them if they have people they can confide in, they'll say yes. Those people tend to have better brain outcomes than people who, who don't have those connections. And if you think about it, again, I don't want to make a sort of, an easy evolutionary

• 49:44Speaker 00

  argument where we just say, this is how we evolved, so this is how we should live now. But I mean, if you think about our evolutionary history, for the most part, we lived in, in a time where social connections were imperative to survival. Right? I mean, if you are living in a, in a hunting and gathering lifestyle, you know, you need those social connections. You can't guarantee that you will find food every day. So you need to have connections with other people who you trust and they trust, who you are willing to share with. Right? And so those social connections become, become inextricably linked to your health.

• 50:21Steven Bartlett?

  Does pollution have an impact on our cognitive performance?

• 50:24Speaker 00

  Yeah, that's been so that's been a surprising and really kind of sad result of a lot of research lately is that air pollution has real negative impacts on brain aging. And we've seen that in acute studies where people have looked at the effects of, you know, what's going on in your in your peripheral blood when you commute in traffic, right? When you ride your bike in traffic, but also from an epidemiological standpoint, people who are living in areas with higher air pollution have a higher risk of developing Alzheimer's disease and other dementias. One of the things that we've done some work on, we were really interested in whether

• 51:05Speaker 00

  physical activity either could, you know, diminish those impacts of air pollution on the brain, but also we were thinking, well, when you're active, you're breathing more, right? Your your your your respiration increases, so you're breathing in more pollution, more particles. So could that actually, you know, have an impact on the benefits of activity on your brain? And we found we've looked at a look at this in a couple of ways and both for some brain structural outcomes and for risk of dementia, exercising in or being physically active in in an area with even moderate levels of air pollution diminishes the benefits of physical activity on the brain, which is a real bummer, especially for me. I live in Los Angeles, which is a very, it's an area with a lot of air pollution.

• 51:49Speaker 00

  And and so being physically active in that environment when there's a lot of pollution in the air, it doesn't, it doesn't make your health outcome worse, but it diminishes the benefits of physical activity.

• 52:02Steven Bartlett?

  So if you go for a run in the middle of London, for example, or in the middle of New York City, the cognitive benefits are diminished?

• 52:09Speaker 00

  That's what we're seeing in the data. We're seeing, and in fact, the study that we did was was from data based in the UK, where, you know, we're not seeing the kinds of levels of pollution that we see in some other cities around the world where it's really drastic, or even in Los Angeles, where it's much higher levels of pollution than we'd see in, say, London. But even in those levels with more moderate levels of air pollution, people who are active in in higher levels of air pollution don't show the same brain benefits as people who are active in areas with lower pollution.

• 52:41Steven Bartlett?

  I had my brain scanned, uh, what, two months ago now, and it was okay.

• 52:46Speaker 00

  Okay.

• 52:47Steven Bartlett?

  It wasn't amazing.

• 52:48Speaker 00

  What do you mean by okay?

• 52:50Steven Bartlett?

  I mean, he just told me there was room for improvement in terms of like, some things he saw in my brain. He also diagnosed me with ADHD following that and a few other questionnaires and things. One of the things in my sort of prescription that he asked me to do more of was racket sports.

• 53:05Speaker 00

  Interesting. Okay.

• 53:06Steven Bartlett?

  He said, if you do this list of things that he's asked me to do, things like hyperbaric chambers and blah, blah, blah, blah, blah. And racket sports, um, will see an increase in certain parts of your brain. Now that somewhat ties into what you're saying with doing this physical activity, but comparing it with some kind of cognitive challenge. Racket sports seems like a prime example.

• 53:29Speaker 00

  Actually, it's funny. It is the number one question I get after I give a talk is about tennis. And I think I probably, you know, I give talks a lot in, in, you know, to communities with, you know, more, sometimes more affluent, older adults who probably play a lot of tennis. But it is, you know, it's an activity that people play, can play later in life, you know, um, and, um, and it does involve a lot of strategic thinking. It involves a lot of fast reactions and it involves aerobic activity. And so it is, it's a great contender.

• 54:00Steven Bartlett?

  And you're doing.

• 54:00Speaker 00

  And you're doing it with someone. It's social. Um, oftentimes, especially when you get a little older, you play doubles. So you don't have to run the court as much.

• 54:08Steven Bartlett?

  What are the other questions, people, after hearing you speak? What are the other questions that people often are most curious about?

• 54:14Speaker 00

  How much activity? That's the big one, right? How much do I have to do?

• 54:19Steven Bartlett?

  Do I have to do?

• 54:19Speaker 00

  Right. And that's the way people think about it. Yeah. And, you know, I think.

• 54:23Steven Bartlett?

  Have to do.

• 54:24Speaker 00

  Yeah. And it, it, it's, it sort of does bum me out to frame it that way because, um, because I think of physical activity as, as something that, as, as we were just talking about. It improves your whole day. Um, it's something that many of us want to do because of that, right? And so I think, you know, first, the first thing I always tell people is find the activity you want to do. Because that's the one you'll keep doing. And so don't look for the perfect, right? If running on a treadmill makes you crazy and you don't want to do it, then you won't keep it up. If playing tennis does it for you, maybe it's not the best if we fit you, if we can even figure out what that means. But you're gonna do it for the rest of your life, then by all means, that's the one to do.

• 55:08Speaker 00

  And so I think that is the first thing that everyone should be thinking about is, you know, what do you, what do you, what makes you excited to get out the door and do? And don't worry about what's best.

• 55:20Steven Bartlett?

  What is the research that you've done that you're most proud of? Or that surprised you the most? Because, you know, I've, I've been looking through your work and found different things that I found interesting. But I must have missed something that you find really fascinating.

• 55:34Speaker 00

  Well, one of the things that I found really surprising was actually, it was, it's now been a while, it's been like over, over a decade ago, I did some work on the endocannabinoid system. And the endocannabinoid system is our body's sort of natural form of marijuana. You know, we produce these chemicals that activate brain receptors the same way that the active ingredient marijuana activates. And so it turns out that exercise upregulates the same system, these endocannabinoids. And that may be why, at least partially, why exercise makes people feel good. And one of the studies that we did, like I said, about 10, 11 years ago now, was we found that the same thing that we get from exercise

• 56:18Speaker 00

  in terms of endocannabinoid signaling, dogs also get that. And I'm, I'm a dog lover and, and I know my dog loves to exercise. And she's, you know, bummed out if she can't get her, her, her walk and run in for the day. And I think there's something similar going on. It's these similar rewarding mechanisms that make them feel good, that, that makes us feel good. So that was one, one really fun and interesting kind of finding that I think has some implications, right? It's, it's if, if, if we can find those activities that generate those rewards, we're gonna wanna do that more often.

• 56:51Steven Bartlett?

  And it also provides a sort of physiological explanation as to why some people who don't exercise or aren't able to exercise can often have depressive symptoms.

• 57:01Speaker 00

  Agree, I totally agree, yeah. And I think these biological mechanisms that can make you feel better when you exercise, they don't always kick in right away, right? And so I also think that can be a little bit of a barrier to someone who's not active, that if you just get up and start exercising, maybe it takes a little bit of time for these things to kick in. You have to be able to stay within a certain intensity level. And maybe if you're not very fit, you kind of overshoot that and you end up going too intense. And you don't get those same sort of mild benefits that just make you feel good all day, right? I think one of the things that people need to kind of keep in mind is maybe try to stick with it long enough to get a little bit of fitness so you can reap those

• 57:43Speaker 00

  rewards. They'll come. You just need to just give it some time, right?

• 57:47Steven Bartlett?

  Have you got any hypotheses that you're working on at the moment that you haven't been able to prove out yet? But as someone that's a researcher and that's insanely curious, there must be things in your mind that you're thinking, I'd love to do a study on that to figure out if that's true.

• 58:01Speaker 00

  Yeah, I mean, so a couple of things. I mean, one, we are not done with the combining cognitive challenges with physical activity. I think that is a really exciting area and it's early on. So I think that the work that we've done and others have done is in its infancy in how we can boost the brain benefits of exercise. And that's going to be a big part of our work going forward is what can we do to really make exercise a little more cognitively challenging and get those benefits? The area that I'm really interested in now is the effects of sitting on the brain. And what are the mechanisms that link too much

• 58:45Speaker 00

  time spent sitting with brain health? And how can we kind of manage that a little bit better? You know, when we think about Exercise participation. And I've been saying, you know, 25% of adults engage in the guidelines for physical activity levels in the US. That number hasn't changed over the last, you know, couple of decades. All the messaging, I mean, you know, would you, could you ever meet someone who doesn't know that physical activity is important to do? But still, 75% of people don't exercise. And so I don't know what it'll take to change that number. But I think maybe we can look at other behaviors that we can change. And sitting is something that everyone does. And so that, I think, is a really nice place to focus, to move the needle a little bit.

• 59:29Speaker 00

  So can we get people to sit less? What are the kinds of interventions we can implement that can get people to reduce their time spent sitting? And will that pay off in terms of brain health? And I think that's, it's a big question. We know that time spent sitting is associated with risk of dementia. We just, we just did a big study looking at, you know, if you, if you sit for 10 hours a day compared to nine hours a day, it's about a 10% increased risk of dementia. If you sit for 12 hours a day, it's about a 60% increased risk of dementia compared to sitting for nine, nine and a half.

• 1:00:03Steven Bartlett?

  60%.

• 1:00:04Speaker 00

  60%.

• 1:00:05Steven Bartlett?

  Versus nine hours a day.

• 1:00:06Speaker 00

  Right. So just a couple more hours, right? It's, it's a nonlinear relationship. So, once you get past about nine, nine and a half hours a day, your risks start going up in, in a nonlinear exponential way. And so, can we alter that? Can we, I mean, it doesn't, it doesn't take a lot necessarily to go from 12 to eight hours a day. So, maybe that's easier than getting people out the door. Maybe we can find some, find some intervention. So that's what I'm really excited about is, you know, some of, some low cost ideas, some low investment ideas for people, um, that could maybe have a big impact on the way they age.

• 1:00:45Steven Bartlett?

  I'm thinking about all kinds of chairs that vibrate and give you an electric shock. I'm thinking of how we can implement that into Wipe, which is a company I've, I'm involved in.

• 1:00:55Speaker 00

  Totally. Yeah. I mean, reminders are one way, right? I mean, I think tracking your behavior, I mean, there, it's not going to work for everybody, but certainly tracking your time spent sitting for a couple of weeks might actually give you a little bit of motivation, once you realize just how much time you spend on these chairs.

• 1:01:12Steven Bartlett?

  What is brain foods? Is there such things as a brain food? I think I much the reason I take Omega is because people tell me it's good for your brain.

• 1:01:18Speaker 00

  Yeah, I don't, you know, I don't think there's a magic pill. You know, I think the best evidence that we have right now is is more plant based, less meat based, especially less processed meat.

• 1:01:32Steven Bartlett?

  More plant based.

• 1:01:33Speaker 00

  More plant based foods and and less meat.

• 1:01:36Steven Bartlett?

  Less meat.

• 1:01:36Speaker 00

  Yeah, here's where the difficulty lies in all of this research. To study brain health, you need to observe people over long periods of time. And so you can't implement a 10 year diet intervention. Just nobody will follow it. So all of the research that's really strong in this area is asking people to report what they eat and then tracking what happens to them over time. So it's it's difficult work, but the best evidence is that aspects of the Mediterranean diet seem to be linked with better brain outcomes. So more plant based, more more legumes, more whole grains, less processed food, less meat, less sugar.

• 1:02:20Speaker 00

  These are, you know, these are the obvious dietary interventions, right? And I think they're they're obvious for a reason because they seem to be so good for so much of our bodies. And, you know, so much of our cardiovascular metabolic health and our brain health.

• 1:02:35Steven Bartlett?

  If there was one fundamental misunderstanding that most people have, that your work and your experience has rebutted, I guess. What is that fundamental human misunderstanding about the nature of our bodies? And how we're supposed to be living to be optimal?

• 1:02:52Speaker 00

  I think I think the most dangerous misunderstanding is how much exercise it takes to get benefits.

• 1:02:58Steven Bartlett?

  Right.

• 1:02:59Speaker 00

  And I think that's because that acts as a barrier to people. And what we've seen from the epidemiological work is that, you know, the the there are minimal amounts of activity that provide big benefits. More is generally better, but you can get huge benefits just by moving your body a little bit every day. And so I think that's, you know, as I said, it's a dangerous misconception because it's a barrier. When someone thinks, when someone doesn't exercise at all and thinks I need to get 12,000 steps per day and I'm tracking it and I'm getting 3,000, that's a pretty big gap. And that's one that maybe. You don't think you can fill, but if you're getting 3,000 and you think if I get to 5,000, I'm going to get a big benefit, that's motivating, right?

• 1:03:44Steven Bartlett?

  It's so true that sometimes going from zero to one feels so inconsequential and somewhat embarrassing that we just don't do it because we, I think many people think of zero to one as like zero to a five day a week gym attendance record.

• 1:04:03Speaker 00

  Right.

• 1:04:04Steven Bartlett?

  Which is just like climbing Mount Everest in your mind.

• 1:04:06Speaker 00

  Totally.

• 1:04:06Steven Bartlett?

  It's just so far away that there's going to be so much psychological discomfort, it's going to result in procrastination. You're going to do something else and you're going to avoid it. But if we refrain that to zero to one being walking for your lunch.

• 1:04:18Speaker 00

  Yeah.

• 1:04:18Steven Bartlett?

  And that as the starting point and then one to two being, as you said, going from 1,000 steps to maybe 2,000 steps. It feels like something everyone can do, but we just don't think it's important. We think it's totally inconsequential to go for a walk as opposed to, you know, just sitting down and ordering our food on an app.

• 1:04:34Speaker 00

  Yeah.

• 1:04:35Steven Bartlett?

  Something that I, I think about a lot because even someone like me that I, I go to the gym, you know, as frequently as I possibly can. However, there are some days like today where I'm extremely busy, where I might have said I was going to go to the gym later at night. And I either think to myself that there's no middle ground. I think that's either going to the gym and working really hard or fuck it.

• 1:04:58Speaker 00

  Yeah, there's great middle ground now.

• 1:05:00Steven Bartlett?

  Yeah.

• 1:05:00Speaker 00

  You can run up the stairs on your way to bed, right? You know, I mean, you really, or you, you know, you can do these exercise snacks, but I like to think of the, the things that you're talking about. You know, walk to lunch instead of ordering in. You think that's not important, maybe it's life changing for some people. It will literally change your life if, if you are doing very little and you take that first step. You know, it can change everything about your, you know, your future in some ways. Because it builds the foundation for, oh, that feels good. Maybe I'll try a little bit more, right? Maybe I'll try a little bit more. You know, we were talking earlier, you were saying, you know, you implement a new exercise regimen and you jump in with everything. And then you end up, you know, getting a Achilles tendon injury or something like that.

• 1:05:45Speaker 00

  You know, that's especially true of people who don't exercise at all. And so, you know, the best thing to do is to start slowly and really start reaping those rewards because that's the motivator. And so, yeah, I mean, I think if you are exercising a lot, you know, day that gets away from you and you can't make it to the gym. I mean, getting a little bit of vigorous activity, going for a really brisk walk, going up the stairs, doing some push up. I mean, anything is going to give you a little bit of benefit. You know, these are really easy things that we can implement into our lives.

• 1:06:17Steven Bartlett?

  Does Alzheimer's exist on a spectrum per se? And is is what one end of that spectrum sort of just general cognitive decline and memory reduction? Because I sometimes wonder, obviously, my job here is to, I interview very intelligent people, and those people come in all shapes, sizes and ages. And I obviously, as an observer, notice how some of the older people that I meet are incredibly sharp, you know, arguably significantly sharper than I am. And I'm, you know, in some cases, thirty percent, forty percent of their age, forty percent of their age. And they're just unbelievably sharp. And then we've also all had experiences, maybe with an elder relative or, you know, someone slightly older.

• 1:07:02Steven Bartlett?

  Where you can see that their memory recall or their sort of, it's almost sometimes you experience it as their self-awareness has started to wane. They might tell you a short story in one hour, if you know what I'm saying. They might, they just, it's almost like the self-awareness of what they're saying and how they're saying it, and their ability to articulate themselves has somewhat slipped away. And I wonder if that exists on this scale of dementia, or whether that's just general atrophy, as you call it, of the brain.

• 1:07:29Speaker 00

  Right.

• 1:07:30Steven Bartlett?

  And I don't, I really, really want to be someone, as I'm sure we all do, that has, my brain works until the day that I die.

• 1:07:37Speaker 00

  Yeah.

• 1:07:37Steven Bartlett?

  You know?

• 1:07:38Speaker 00

  Yeah, we all want that.

• 1:07:39Steven Bartlett?

  Yeah, we all want that.

• 1:07:40Speaker 00

  Of course.

• 1:07:41Steven Bartlett?

  And that's why I wonder if it's the spectrum or is, it is a spectrum.

• 1:07:44Speaker 00

  Yeah, I mean, so there's sort of a normal amount of cognitive change that happens with aging in most people that, in general, should not impact your daily life greatly, right? You should still be able to do all the things you want to do, navigate your world in the way that you want to. You may have some, you know, it's inevitable that there will be some memory changes, some changes in your, in your executive functions, planning, but not the kinds of profound changes. That we see in people with dementia. And so dementia is cognitive decline that impacts your daily life in a way that makes it hard to keep doing the things you want to do. When you start to get down into sort of the nitty gritty

• 1:08:27Speaker 00

  of different types of dementia, Alzheimer's disease, which is by far the most common, has a lot of pathological features that make it a progressive disease, right? That mean, you know, you will continue to decline over the course of the disease and there's no way to stop it really that we know of. But there is gonna be, there's always gonna be some change in your brain with age that you can't fully stop for most people.

• 1:08:49Steven Bartlett?

  I've also always wondered about this, this is totally random, but I've said this a few times to a few people, this idea that when a spouse or a partner passes away, people seem to go into pretty quick cognitive decline and that sort of mortality risk seems to multiply. And that could be a very complex thing to do with cortisol and other things going on in the body and hormones. And but I wondered if there was accelerated atrophy, if my, if I'm 85 and my wife passes away.

• 1:09:15Speaker 00

  Yeah, so I mean, a couple of things are going on. Grief in itself is associated with brain changes. There's been interesting work on that.

• 1:09:23Steven Bartlett?

  Brain changes?

• 1:09:24Speaker 00

  Yeah, I mean, that there are cognitive changes and structural changes that happen when you're grieving. I think some of this is depression as well, that's clear. And one of the things, you know, untreated depression can start to look a lot like dementia. It's a risk factor for dementia, but it can also look like dementia because when you're undergoing depression, a lot of things happen. You stop paying attention when you're talking to people. You're, you're, you're not as present. And so, you know, what can sometimes seem like a memory deficit might be because you weren't able to pay attention to what was going on in the first place. And so I think one of the things that I worry about with older adults a lot is making sure that depression is treated.

• 1:10:06Speaker 00

  Because especially when there are cognitive challenges that they're, they're experiencing, they're, they're feeling like they're have declines in their thinking and memory skills, making sure they're not depressed is the first step because you can treat that. And actually, you can treat that really well with exercise. So you might be able to get a couple of bangs for your buck by both treating your, you know, helping to manage your depressive symptoms and getting the brain, other brain benefits. But you can also treat it pharmaceutically. Or with therapy, and that can have a profound impact on the way that you think and the way that you manage those symptoms. So yeah, I think losing a partner, you're also losing a social connection. And we know that social connections are so important.

• 1:10:47Speaker 00

  And so that loneliness and that loss of a social connection is important. So I think that's, that's all wrapped up in these brain changes. And these are all modifiable things. We can watch out for our parents or people in our community when these are things are happening and try to help them maintain better social connections.

• 1:11:06Steven Bartlett?

  We have a closing tradition on this podcast where the last guest leaves a question for the next guest, unaware of who they'll be leaving it for. And the question left for you, interesting, maybe a little bit obvious, but how can your work help the world?

• 1:11:20Speaker 00

  It's a simple answer, I guess, but I think it's profound, that if you, if you sit less and you move more, you will not only help yourself, but you will also help the general population, right? I mean, when, when we talk about aging, it doesn't just affect you, right? It affects everybody around you. It affects your family, caregivers, it affects our economy. I mean, the US is, is, is, is, we're thinking the US might end up spending a trillion dollars a year on Alzheimer's disease by 2050, right? And so prevention will have a big impact on our economy. And I'm not saying people should

• 1:12:01Speaker 00

  implement sitting less and moving more for our economy, but by doing that, you might actually, on a broad scale, have a big impact on, on our world. And so, you know, I hope that that message gets out there. That's why I'm so, I was excited to, you know, to do this podcast with you because, you know, I think it is a message that we need to keep repeating and, and find ways to help people do that, because I think it can have a profound effect on themselves, their family, and society.

• 1:12:29Steven Bartlett?

  Are you hopeful?

• 1:12:30Speaker 00

  Well, that's a hard question to answer. I mean, I, I am on some level because I think, you know, especially with the focus on, you know, start moving away from having people do big steps and trying to get people to do small steps first. I am hopeful that we can motivate people to, to implement these, these changes. I, I hope it's possible. It's been hard to do.

• 1:12:52Steven Bartlett?

  Is the, the data going in the wrong direction at the moment? Generally.

• 1:12:56Speaker 00

  You know, we just haven't seen big improvements in adherence. And I think one of the things I'm worried about is that worldwide, more countries are becoming more like the US and UK instead of less, right? And our societies are aging. And so, you know, we have a larger number of older people. And so just by the sheer numbers, we're going to have more people with these diseases. And so, you know, implementing these increases in activity, reductions in sedentary behavior, hopefully will have these kind of profound effects on our aging society. But I think it needs to be our focus. Like, right now, you know, when we think about Alzheimer's disease, we don't have drugs that are going to have a big impact.

• 1:13:41Speaker 00

  I mean, there's some new drugs that are promising, maybe. But the biggest thing we can do is prevention. And that's where this work comes in, is, you know, if we can prevent or delay, we can save people happiness, I mean, improve their happiness, and we can save money and we can improve society.

• 1:13:59Steven Bartlett?

  David, thank you.

• 1:14:00Speaker 00

  Thank you.

• 1:14:00Steven Bartlett?

  Absolutely incredibly enlightening and inspiring, and maybe most importantly of all, motivating conversation. Motivating because knowledge is power. And you've given me so much knowledge, which has added fuel to a bunch of different behaviors that are critical for my cognitive outcomes, but also just my overall day to day health. So, thank you so much for that. Thank you so much for doing the work that you do, because I know you're probably doing it in part because you're incredibly curious and you love it. But the other part of that is it's an incredible service to all of us that you go out there and you take this time to do all this research that you then pass out to society in a way that's going to serve us and get us close to the goals that matter most, keep us healthy

• 1:14:42Steven Bartlett?

  and happy into our later years and keep families together ultimately. So, thank you for the work you do, and thank you for being here today.

• 1:14:48Speaker 00

  You're welcome. Thanks so much for having me on. It's been a pleasure.

• 1:14:52Steven Bartlett?

  Do you need a podcast to listen to next? We've discovered that people who liked this episode also tend to absolutely love another recent episode we've done. So I've linked that episode in the description below. I know you'll enjoy it.