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Physical exercise helps grow new brain cells – neuroscientist

Life is motion and motion is life – the benefits of physical activity are hard to overestimate. How exactly does it influence the workings of our brain? We ask Wendy Suzuki, professor of neuroscience and psychology at the New York University Center for Neural Science.

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The text of the interview has been edited for clarity.

Sophie Shevardnadze: Wendy Suzuki, Professor of Neuroscience and Psychology at the New York University Center for Neural Science. Wendy, great to have you with us. Welcome to our show.

Wendy Suzuki: Thank you so much for having me.

SS: All right, so we all know that physical activity is beneficial all around and effects are obvious, not only on the body but also on the mind. And whenever I feel blue, I'll go jogging or work out a little or dance a little, and I feel better afterwards. Can you explain the simple chemistry behind all of this?

WS: Absolutely. There is a direct cause and effect relationship for what you've just described, which is if you're not feeling good, you need, you know, a little pick-me-up mentally, maybe anxiety is going up, a simple walk outside can lift your spirits. Why? Because moving your body can literally stimulate the release of a whole what I like to call a bubble bath of neurochemicals in your brain – these neurochemicals you've heard of, they're called dopamine, serotonin, noradrenaline. So you're literally giving your brain this bubble bath of good-mood neurochemicals when you move your body and that is why you feel better, you feel more energised, you feel less anxious, less depressed. And it is if you are changing the neurochemical environment of your brain.

SS: Alright, so exercise boosts dopamine and happy hormones. But does a boost of cognition come from actual exercise or from happy hormones?

WS: Yeah, that's a great point. So in fact, moving your body does many different things, to many different brain systems. We started with those feel-good neurochemicals, serotonin and dopamine that go up with a workout. But other things are happening. That's why I like to call it this kind of ‘neurochemical bubble bath’. It's not just the dopamine, and the serotonin, there are many different kinds of growth factors that increase as you move your body. And it's those growth factors that start to literally change the anatomy, the physiology and function of your brain. And this is a part where people start to say, ‘Wow, I didn't know that.’ I think people have an instinctive understanding that going out and taking a walk or moving your body can make you feel better. But moving your body literally can strengthen, it's like your brain becomes kind of a muscle. With movement, you're not just strengthening your biceps and your triceps, you are literally strengthening the connections, in fact, in certain brain areas, you're actually stimulating the growth of brand new brain cells in one particular area that I've studied for the last 30 years, called the hippocampus. The hippocampus is critical for our ability to learn and retain new long-term memories for facts and events. And if any of you out there want better long term memory, getting those regular exercise bouts that increase those growth factors, that's when that's going to get you a bigger, fatter, fluffier hippocampus and better memory.

SS: So if physical exercise literally increases the capacity of the brain and therefore improves our mental state and cognitive abilities, I wonder why, for instance, hockey players or, you know, football players or baseball players, why don't we see them getting their PhDs or getting research grants or whatever?

WS: Yeah, so, you know, it's not going to make an F-student an A-student, it is going to improve, where you have to start with. And, in fact, soccer, football, many of these sports, particularly the contact sports, there is a give and take, because that trauma that comes from even heading the ball in European football, or what Americans call soccer, not good for your brain. So all that benefit — and they are getting benefit from the regular exercise — is a little bit mitigated by the brain trauma that some of these sports players kind of expose themselves to. So again, it's not like a magic formula that makes everybody Einstein. From where you are, are you going to have a better memory? Are going to be more focused? And we didn't even talk about the improvement of focus and attention that is dependent on the prefrontal cortex. That is probably partially due to increases in growth factors as well. But actually, that is one of the most common improvements that you see, with increasing your physical activity, you see a clear improvement of your focus and attention. And that is something certainly all professional sports players really need, they have this ability to focus on – for baseball players, that ball coming so fast to them, even soccer players, keeping track of all of the people on their team and where they are and making quick decisions about ‘where I need to be to get my team to score’, all of that is dependent on the prefrontal cortex. And in fact, we probably are seeing those benefits in those elite players that are using those kinds of attention and focus skills to be the elite athletes that they are.

SS: Alright, so you're saying that physical exercise alone – is enough for boosting one's cognitive abilities? Or does it only work along with other mental exercises like acquiring new skills or learning new languages?

WS: Right. So, you know, you're getting into my favourite topic, which is the topic of brain plasticity. What are those things that we can use to help improve our brain functions and make our brains function better? Exercise is one of them. And kind of the wow for the exercise is the stimulation of brand new brain cells in that hippocampus. Everybody wants a better memory, and also the hippocampus is very vulnerable to ageing and neurodegenerative disease state. So kind of a bonus is those regular athletes that are working out regularly through their life are building up this hippocampus that will literally help stave off any neurodegenerative disease states that come on later. Why? Because their hippocampi will be bigger and fatter, they’ve been growing hippocampal cells all along. But that is absolutely not the only thing that can make your brain work better. For example, sleep – very, very important. People often ask me, “Okay, so you're telling me that I should get only five hours of sleep and get up and do that workout because that's really important?” No, lower hours of sleep is very detrimental to overall brain function. So you want to do both. You want to give your brain that good eight hours of sleep so that it can go through all of its electrophysiological cycles. What is that doing? That is refreshing the brain, that is literally clearing out all the toxins that can build up overnight. And those eight-hour sleep bouts are the best thing to refresh your brain. So in that state, then you go work out and give your brain that extra boost of good-feeling neurotransmitters and growth factors and you get the maximum benefit out of that. And then on top of that, what do you do? You go and learn a new language, you use your brain, you use the prefrontal cortex and the hippocampus, which is also very, very beneficial. You might sleep and you might exercise, and then if you watch TV all day or do nothing, you know, engaging your brain, that will not nearly be as beneficial as you use your brain, all these brain areas that you've benefited from sleep and exercise, and then you use it to engage those brain areas and learn something new.

SS: What if you're watching, I don't know, really useful TED lectures all day long on TV, does it count as a mental exercise?

WS: Sure, if you are learning something, now we have so many different methodologies or venues to learn something new. I was thinking more of just the mindless TV that one can watch when just one wants to, you know, unplug. But yeah, absolutely. One can learn great things from TED Talks, from YouTube videos, learning new things in any way is beneficial to the brain.

SS: Sports, you're saying is especially important for kids. I think it not only helps their healthy growth but also socialisation as they learn, I don't know, competition, teamwork, leadership, simply make friends in sports sections. Is it the actual physical activity that is providing mental benefits in this case, or the social activity and learning to strive, to fail, to succeed?

WS: Yeah, you know, all of that. That's a great question. And exercise is great for all the reasons that I said. But we as humans are social animals, we have huge networks in the brain that have evolved to be social, to recognize facial expressions and kind of decode even complex social interactions in our teammates, in our schoolmates, in our workplaces, and so all of that, especially positive social interactions that kids can get in sports teams, are something that is another learning opportunity, and that together with the physical activity, absolutely, they're working together to improve brain function. And I would say, not just kids, it's just as important for us, 40- and 50-year-olds, to stay active, stay social, and we continue to reap the benefits of that long after we've gotten out of grade school.

SS: So how early on would you advise introducing your kids to sports?

WS: My philosophy is that, just from observing friends and people, it's about creating a lifestyle that naturally has a movement in it. Pets are great, take your dog for a walk, make that part of your life so that you miss it if you don't have it. And then instead, if you don't have the pet around, go for a walk with your friends, your sister, your brother, your mother, your father. So not everybody will love sports. And I think it's really important to keep an open mind about what constitutes physical activity. Some people will love dance, some people will love just nature walks outside, all of that can count as regular physical activity. And I think, kind of making that part of the habits of our young kids, including in schools, including physical activity or sports or other things that kids that don't like sports can also participate in, is a really important kind of strategy for governments to take in, in regards to brain development, brain health in our kids.

SS: Is there any evidence to suggest that those kids who do sports actually do better in school than those who don't? 

WS: Yes, there is. There are significant correlations between school performance and participation in sports that have higher levels of physical activity. And as you were implying, it also helps because they have to learn how to manage their time in a much more challenging way than those that aren't participating in those hours-long sports practices and still have to fit in their homework, their writing, so they are somehow fitting that all in by becoming more focused, by becoming more organized. And what is that stimulating? Prefrontal cortex and your ability to shift and focus and order things in your life. So a lot comes with that in addition to the wonderful effects of physical activity on the brain.

SS: Is there such thing as over-exercising that is actually hurting your brain? Like, for instance, if you over-exercise you can hurt your muscles if you overdo it.

WS: No. So everything in brain plasticity... Too much sleep is bad. Maybe too many blueberries are probably bad. Yes, too much exercise is bad. Have we studied that? No, because it's hard to get people to exercise that much to make it bad, to really do damage to the brain. But just looking at oxygen consumption at high, high levels of physical activity, you get diminishing returns. And so that's actually often a question I get, you know: ‘If I join your exercise study, Professor Suzuki, what if I exercise too much, and I hurt my brain?’ And the answer is, yes, theoretically, you can get to that. But really, practically, that would be elite athletes that are pushing themselves so hard, that it becomes detrimental, and practically very few of us can get that to that level of activity. But theoretically, yes, you can. Just like most anything else, it is a U shaped curve, where too much is bad.

SS: Is there any particular type of sports that you think is better for the brain elasticity – athletics, team sports, mind sports? I mean, where does chess fit in all of this?

WS: Yeah, yeah. So the thing that I have come to appreciate, is that it's not one thing that physical activity is doing for the brain, it is doing many things for many different brain areas. And depending how you structure, how you create your physical activity, you are going to get benefits in certain areas and not in other areas. So for example, the growth factors, let's say you want to maximize growth factors, so that you get as many hippocampal cells as possible that suggests that you want to do aerobic activities that really get your heart rate up. So all the running and soccer, track, become a runner – that will get you that regular increase in aerobic activity. But that might not give you the best mood that you can get. Mood improvement may come with lower levels of activity, including walking. And I like to emphasize that because I don't want people coming away from this interview saying, ‘Okay, well, I'm just going to have to become an Olympic athlete to get those benefits.’ No, you can start walking, you can start walking more, and start to see these benefits of mood boosts without having to worry about becoming that Olympic level athlete. And then to go back to your comment on chess – so chess obviously has no aerobic capacity but great strategic skills and prefrontal cortex. I use chess as my example for what happens when you really push the prefrontal cortex. Well, you can picture that whole chessboard and then be able to manipulate: what if I do that move versus that move? What does that going to do and what is my opponent going to do? Keeping all of that in mind that chess players do so incredibly well is a huge development of the prefrontal cortex. So that practice has improved the prefrontal cortex function. You are engaging and improving prefrontal cortex. So let's take that back to exercise. Well, what is that sport that includes both physical activity and lots of strategy? Maybe it could include soccer, there's a lot of strategy there, American football, all the plays, that the players have to memorise and execute on a dime a lot of strategic play up there as well. So it really depends. That's the power and the wonder of the brain, our human brain is responsive to what life brings at it. So, you know, a stayer will have a different pattern of brain plasticity, positive brain plasticity, then a soccer player, is one better or worse? No, but depending on those elements of that life that you're creating in sports, you're going to get those particular benefits. And you get to benefit in the way that you construct your physical activity.

SS: What is a tailored exercise for the brain? I know that you're working on something like that, right? Like, bodybuilders know, for instance, what machine to use today for triceps or whatever. Should we be able to know what routine to follow for hippocampus boost or something like that?

WS: Yeah, I've been very interested in that and trying to come up with platforms that measure your particular benefit from exercise. And what I've seen is there's a lot of individual variability. Where does that variability come to? I'm not saying that, oh, some people have no brain benefit and other people have maximum brain benefit. Generally, they all benefit. But some people have a bigger benefit from a particular workout for their mood and less for their cognitive or memory function and vice versa. And so that tells me that there are kind of individualised programs that one can create to work on what you want to work on. So not everybody wants to work on mood. Maybe you're satisfied with your overall kind of mood performance, and you want to focus on prefrontal cortex, what are you going to do? What is that particular workout that will most boost your prefrontal cortex or your memory function, your hippocampal function? And those are questions that neuroscientists can answer very generally, at this point. And so I've been interested in trying to really make that specific and specific for individuals. And even in the mood, I just said, you know, you're not interested in mood. Well, I think mood is particularly important these days with anxiety and depression levels, some say, 30 to 40%, higher than they were this time before the pandemic. And we know that exercise can really be a wonderful way to address those anxiety, depression feelings. Well, what is your best formula? And what is the minimum amount of work you need to do to get those mood benefits so that you're not feeling overwhelmed, you can use your own personalised formula to get that boost and then go through the day and be more productive and be more happy in your life?

SS: Do you see in the nearest future fitness specialists going through a neuroscience crash course so that you know they can be able to guide their clients through a brain-friendly workout?

WS: Absolutely, that is part of what I am working on. I’m approaching it from the mood perspective, because of what I just said of the really important work that needs to be done to address anxiety and depression. I have a book coming out September in the United States called ‘Good Anxiety: Harnessing The Most Misunderstood Emotion’. And so what are those tools, both exercise, cognitive, behavioural tools that you can use to kind of change your anxiety story from one that it's just all negative, – ‘oh, I hate anxiety!’ – and can you make anxiety into your superpower? So that will involve not just coaches and trainers, like physical coaches and trainers, but perhaps behavioural coaches and trainers to use these tools that neuroscientists and psychologists and psychiatrists have used to really come in and use the principles of brain plasticity to address and really nip it in the bud and also plan for those situations that you know give you anxiety over and over and over again. Well, what can you do to shift that story and flip it on its head and make that situation an advantage to you? That's what the book talks about.

SS: Wendy, thank you so much for this wonderful insight into the world of fitness/ neuroscience/ brain elasticity. It was really great talking to you. I'm going to take in all the advice that I've heard today and good luck with your future research, and I hope we get to do this soon again. 

WS: Wonderful. Thank you so much for having me. 

SS: Thank you. Bye. 

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