Building the Brain: Finding the Cognitive Benefits of Physical Activity

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Transcript

Nathaniel Chin: On today's episode of Dementia Matters, we are going to talk about exercise and brain health. My guests are both exercise physiologists and research specialists working in the Okonkwo lab at the Wisconsin Alzheimer's Disease Research Center. Sarah Lose conducts maximal graded exercise testing in research participants and coordinates the FAB and LIFE studies. She received her bachelor's degree in kinesiology from UW-Eau Claire and her master’s degree in human performance with an applied sports science emphasis from UW-LaCrosse. Max Gaitan is the site coordinator for the EXERT study, an NIH-funded clinical trial for the exercise training for mild cognitive impairment. Max completed a bachelor's in kinesiology and a master’s in exercise physiology at the University of Virginia where he studied exercise as prevention and treatment for metabolic diseases. Welcome both of you.

Sarah Lose: Thanks for having us.

Max Gaitan: Thanks so much.

Nathaniel Chin: To start, I would like for you to clarify some of the terms that are often used in exercise research. What is the difference between exercise and fitness, and where does physical activity fit into these concepts?

Max Gaitan: Well, exercise is really a behavior. While fitness is a characteristic of the body. And in terms of physical activity, it's also a behavior. But there is a distinction that's really important between physical activity and exercise, and that is that physical activity is anything that you do to move your body. Whereas exercise is structured and repetitive and an intentional behavior.

Nathaniel Chin: So physical activity is the general broad category, and you would say exercise fits underneath that specific one.

Max Gaitan: Exactly.

Nathaniel Chin: Okay, if you're exercising, you're having physical activity, but it doesn't work the same way. Physical activity may not always be exercise.

Max Gaitan: That's correct. And it's a really important distinction because exercise is known to have a specific benefit to the body and to health and to the brain that physical activity doesn't necessarily have.

Nathaniel Chin: Okay. And that's why all these research publications coming out specifically address exercise and not necessarily physical activity.

Max Gaitan: Exactly. And that's why a lot of exercise trials and studies that are coming out are focused on an exercise intervention itself rather than just counting how much physical activity a person is actually getting.

Nathaniel Chin: These are very specific things that you guys are looking at when we talk about exercise and brain health. But you're not saying that physical activity is bad, just that it may not be enough, or it's not specifically being looked at.

Sarah Lose: So in our lab, we have actually looked at physical activity itself. And in one of the studies, it was determined that physical activity did help risk for developing Alzheimer's disease. And this is looking at physical activity, not fitness levels. So we tracked individuals; physical activity throughout a week using an actigraph device. So it's an accelerometer, kind of like a Fitbit, that people wore. And then based on their activity, we could split them up into different groups. And we found that moderate intensity physical activity actually had the most benefits.

Nathaniel Chin: Oh, okay. So this has been looked at, because I talked to my patients about physical activity. I intentionally don't use the word exercise, but I know that you guys will be talking about exercise specifically today. So physical activity is still a good thing.

Sarah Lose: Yes. There's just little differences between physical activity and fitness. Although physical activity can lead to increased fitness, there are other factors that contribute to someone's fitness level. So they are slightly different even though they're related.

Nathaniel Chin: I think that's important for our listeners to know, because even though we're talking about exercise at times in this podcast, physical activity, regardless of how intense it is, is still better than sitting and not being active. One of the main arguments for physical activity in the world of Alzheimer's disease is its potential to contribute to resilience or what we refer to as a cognitive buffer. So if you could, share with us what is meant by this term “buffer” and “resilience” and what it means to an aging brain.

Sarah Lose: So what we mean when we talk about resilience or cognitive buffer, first we need to understand that Alzheimer's disease, there's different pathology going on in the brain. So we have an increase in proteins. But then there's also the clinical aspect where we see symptoms occurring. And what we have found in some autopsy studies is that people have these proteins in the brain, but they never showed any of these symptoms that we would see. So from that, what we were able to kind of think about is that some people are able to handle these proteins being in their brain and not show the symptoms. So there's something there that either delays the onset or can change the course of the disease itself. And there's things such as sleep, diet, social engagement, physical activity or fitness, brain engagement, things like this that may be related to this resilience.

Nathaniel Chin: So then what does the literature currently show for things like exercise and brain health?

Max Gaitan: Well, in part it depends on what population you're talking about. So for example, there seems to be great benefit for people who have normal cognition, in terms of even improving say, executive function, which is a specific part of cognition. But we also know that across the board, across all populations, that exercise increases blood flow, which is really good for the brain, that it increases brain plasticity, which is how the brain cells and neurons talk to each other. We also know that it seems to be important for an exercise program to improve someone's fitness to actually deliver these changes to the brain.

Nathaniel Chin: When you say executive function — now in my clinic, I'll often say that's our ability to multitask, to plan, to organize, to do a sequence of things correctly. And that's what you're referring to?

Max Gaitan: Right.

Nathaniel Chin: So when people exercise, and oftentimes I feel this way after I'm done, I feel like my thinking is just better, I'm able to get ideas quicker and get things done in a more efficient way. So in essence, that's what you're talking about.

Max Gaitan: Originally studies would examine these cognitive changes after just one bout of exercise. But then researchers started looking at more longitudinal changes. So they would do exercise interventions and then measure cognition before and afterwards. So it's not just one exercise session, which is good, although that's true. It's really the cumulative effect over time. That seems to be most beneficial.

Nathaniel Chin: But I noticed that you didn't mention memory as a potential benefit. So has exercise not shown a specific benefit for our memory function?

Max Gaitan: A recent study that came out just a few a weeks ago showed that an exercise training program of about one year increased the size of the hippocampus among people at risk for Alzheimer's disease. The hippocampus is the memory center of the brain.

Sarah Lose: And we've actually found in our own center as well, that individuals as they age, we can see benefits to physical activity on their memory scores. And again, this hippocampus. So we broke people up into physically active and physically inactive, and those who are physically active had a greater hippocampus volume. They also had higher memory scores compared to their inactive peers.

Nathaniel Chin: Well, so it sounds to me like now physical activity or exercise specifically can help with your executive function, your memory, your attention. I know personally, wellbeing. So there are a lot of benefits to us, and science is starting to show that.

Sarah Lose: Exactly. And that study I was just talking about also looked at what we call glucose metabolism. So the brain’s fuel. And again, the individuals that were physically active are able to utilize the brain's fuel much better than those that were inactive. And that amyloid protein that's linked to Alzheimer's disease — physically active individuals had less of that throughout the years compared to their inactive peers.

Nathaniel Chin: You two are a part of a very important lab here at the ADRC and the Okonkwo lab is really helping lead this push into exploring physical activity, exercise and Alzheimer's disease. What are your specific studies showing?

Sarah Lose: So, I helped coordinate two studies. The first one is the FAB study, or the Fitness Aging in the Brain study. And that is looking at individuals at one time point, and we are looking markers within the brain as well as their fitness levels and physical activity levels. The LIFE study, so this is a Longitudinal Impact of Fitness and Exercise study. It goes off of that [FAB study], but now we're bringing people back in after two years so we can see how their changes in the brain and their changes in fitness or physical activity track over time — do they track together, or do they track separately? So that's something that we think is going to be very beneficial to understand this relationship. Overall, what our lab has found, is that physical activity and fitness can diminish or dampen both the effects of age and a genetic risk, or predisposition, to developing Alzheimer's disease.

Nathaniel Chin: And that's a pretty powerful statement because we can't really control that we're getting older, and there is this belief that we are what our genes tell us we are. But you're telling me that in essence, physical activity and exercise may have a way of modulating, adjusting, modifying these things.

Sarah Lose: Exactly. And that is a really, like you said, a really big and strong point that we're making. And to give a great example of it, we had individuals who have this APOE 4 gene. So again, they're at a greater risk for developing Alzheimer's disease just based on having this gene. We also had individuals who did not have this gene. And this gene is related to the accumulation of the amyloid protein in the brain. And what we've found is that individuals who had a high fitness level, they if they had this APOE 4 gene, so a higher genetic risk, they did not have any more amyloid in their brain than individuals who did not have this genetic risk. Whereas individuals who had low fitness, you saw the difference in amyloid between these two groups.

Nathaniel Chin: Well, that's pretty powerful, because there's a lot of listeners, I'm sure, that are worried about developing Alzheimer's disease because they have a family history or they know that they have that genetic risk. And if they were to be to a certain degree of physical fitness, that might have a protective effect against that gene. 

Sarah Lose: Exactly. 

Nathaniel Chin: So what other studies are being conducted in the Okonkwo lab?

Max Gaitan: So there was one that, we conducted a few years ago and it was actually an exercise intervention. So it was a six month exercise program where our participants were exercising three times a week for about 50 to 60 minutes per session. So they were really meeting the national public health guidelines for exercise. And what we found is that after that program those people that increased their fitness level — their cardio-respiratory fitness — had better uptake of glucose in the brain, which is the brain's preferred fuel. They were also able to utilize that fuel better.

Nathaniel Chin: So in essence, physical activity and exercise enhance the brain's ability to function?

Max Gaitan: Right, exactly. And along with that we actually found that they improved on their executive functioning too. Again, a test of cognitive function.

Nathaniel Chin: So where do you think the direction of the field is going now?

Max Gaitan: There are a couple of things that we really need to establish with exercise and brain health and Alzheimer's disease risk. One would be the exact amount that is needed in order to see a benefit. While it seems like these public health guidelines of about 150 minutes a week of moderate intensity activity seems to be sufficient, we don't know what the optimal dose might be. Along with speaking about dose, we need to establish what intensity of exercise is best, and maybe even what paradigm is best in other diseases. Exercise trials have established that, for example, maybe high intensity interval training is better than continuous moderate training. That hasn't been studied in Alzheimer's disease yet, and it's very possible that one paradigm of training might be better than another.

Nathaniel Chin: So we still need to figure out total duration and the intensity of it. Because that leads me to my next question, which I know many of my patients and our listeners have, which is: Is there a particular activity that is better for the brain than another one?

Max Gaitan: At this point, what we can say is that studies that exist right now and from our lab show that a moderate intensity activity is sufficient. But it's really about repetitive and continuous motion. And so a great example of that is walking. Getting out for a 30-minute walk is absolutely perfect. If you can't get out for a full 30 minutes, we do know that about 10 minutes at a time is necessary to show benefit. So it's best to do, you know, bouts of at least 10 minutes throughout the day.

Sarah Lose: And to add on to that, with the research that has been done, most of it follows the American Heart Association guidelines for meeting the minimum recommendation for physical activity. And that's going to be 150 minutes a week of moderate intensity exercise. So you can think about going out for a walk at moderate intensity, 30 minutes, five days a week. That's all that we're asking for.

Nathaniel Chin: So then, Sarah, can you define for us what moderate intensity means?

Sarah Lose: Absolutely. So a great way to think about intensity is you're getting your heart rate up. And one way that we can measure this easily and kind of arbitrarily is something that we use called the Talk Test. So if you are exercising and you can sing, you are at a low intensity. Your heart rate is kind of up and not too much. If you can talk but not sing, then that means that your more of a moderate intensity. So again, your heart rate is up even higher at this point. And then if you can talk only a couple of words at a time before having to take a breath, you're working at more of a high intensity. So your heart rate is even higher.

Max Gaitan: Yeah, I'd actually like to jump in. So all this is to not discount say stretching and muscle strengthening exercises. We do know that those are important for overall physical health. So we definitely don't want to discount those, and those should be incorporated into a healthy exercise routine.

Nathaniel Chin: That's a really good point cause we don't want anyone getting injured because that would get in the way of them doing routine daily exercise. Okay. You two are entrenched in the field and I noticed that you're both fit appearing. So what is it that you do? And then I want you to end by telling me what do you tell your family members to do?

Max Gaitan: I’ve been triathlete for a number of years. So I trained for triathlons. I spent a lot of my time swimming, biking and running. I do my best to work in muscle strengthening activities so when I can. And I keep engaged by being active with friends as much as I can; the social aspect is big to me.

Sarah Lose: I have been a runner my whole life, so I continue to run, but again, I incorporate the weightlifting exercises into that as well. And also just as Max said, going out and doing activities that aren't necessarily at the gym. So going on a hike to Devil's Lake or going kayaking for an afternoon, just things like that are how I stay active as well.

Nathaniel Chin: So it seems like you guys have a nice balance of intentional exercise the way we traditionally think of it, but then really trying to be active, just mobile, when you're not exercising.

Max Gaitan: And sometimes I absolutely love my triathlon training, and some days I'm not super motivated to do it. So on those days, maybe I'll kind of force myself to, but I'll still get out and do something that I want to, like going for a kayak or going for a walk.

Nathaniel Chin: Okay. Well then to end, what do you say to your family members? Because they're not in their twenties and thirties, and they're not triathletes  or long distance runners.

Max Gaitan:  I really encourage them to be as active as they can. And, again, the social aspect of exercising is really important. So for example, my parents had been going to exercise classes with their neighbors at the local gym and finding a lot of benefit from that.

Sarah Lose: I also tell my family members to just find something that they like to do because you're going to be more willing and wanting to go do this exercise if you enjoy doing it. So for example, my mom and dad both love to swim. So they go and they swim. My dad will go on the elliptical cause he likes that; my mom doesn’t, so she goes on the treadmill. So things like that. There's not a one method fits all for everybody, so just do what makes you happy.

Nathaniel Chin: Well, I think with that, I'd like to end and thank you both for being on our podcast today.

Sarah Lose: Thank you.

Max Gaitan: Thanks so much, Nate.