Impacts of Exercise on Brain Health

Recent research from the Wisconsin Alzheimer’s Disease Research Center has shown the protective benefits of exercise in maintaining brain health and preventing Alzheimer's disease. Guest: Ozioma Okonkwo, PhD, assistant professor, Division of Geriatrics, University of Wisconsin School of Medicine and Public Health, and neuropsychologist, UW Health Memory Clinic

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Intro: Welcome to Dementia Matters, a podcast created by the Wisconsin Alzheimer's Disease Research Center. It's our goal to humanize Alzheimer's research so that our community, our patients, our participants, and anyone else interested can get a better understanding of the work that's happening to fight back against this disease. My name is Nathaniel Chin, and I'm a geriatric memory clinic physician at the University of Wisconsin. I'm also the family member of someone living with dementia. I'll be serving as your host for this podcast and asking the questions I believe are in the minds of many in our community. Thanks for joining us.

Chin: Today, we welcome Dr. Oziomo Okonkwo, a neuropsychologist who sees patients in the UW Health memory clinic in Madison, Wisconsin. Dr. Okonkwo has received a lot of attention recently, including an article in Time Magazine on the findings of his recent exercise research conducted through the Wisconsin Alzheimer's Disease Research Center. It's a very relevant topic, and we're excited to talk with him about it today. With that, we welcome Dr. Okonkwo to our very first episode of Dementia Matters. Thanks for joining us.

Okonkwo: Thank you.

Chin: To begin, I was wondering if you could share with us how you got into exercise research.

Okonkwo: Well, thank you. That's actually a very interesting question. So, I came here and I met with Dr. Mark Sager, who at the time was the director of the Wisconsin Alzheimer's Institute, and he said to me “you know, have you thought about something like physical activity or exercise?” I said, “you know, I have, but it's not an area where I had done much work before now.” So, he goes, “well, we've been collecting a bunch of data on physical activity, and if you would like to take a look, it's yours.” So, I said, “sure, why not,” and when I looked at the data the findings were unbelievable. I mean, I could not make this up if I had wanted, you know? We looked at four different areas of measurements—we looked at the amount of amyloid in the brain, we looked at glucose uptake in the brain, we looked at atrophy of brain tissue, and we looked at cognitive function. Across all four domains, the findings were consistent—that even though we all know that age is the biggest driver of changes across these four levels of measurements, when you stratify the sample by those who are physically active or inactive, age effect was only present in those who are physically inactive. Those who were physically active somehow seemed to defy the well-established effects of aging on these four measurements. I was hooked. That was it, and I've not looked back since then.

Chin: To clarify, define physically active versus inactive.

Okonkwo: So, for that study, we went by the American Heart Association criteria for physical activity in adults, which is a half hour of moderate intensity physical activity up to five days a week. So, that was what we used to define those who deemed to be physically active and contrasted them with deemed to be physically inactive.

Chin: Okay, and, so, from this initial study—yes, we now have a recent publication from you in the Journal of Alzheimer's Disease just this year, in 2017, discussing physical activity and brain glucose metabolism, or the use of brain glucose.

Okonkwo: That's correct.

Chin: Now, this is a really popular study—it was even written in Time Magazine. Could you comment on the findings?

Okonkwo: So, in this study, we looked at how brain glucose metabolism varies as a function of the intensity of an individual's week-long physical activity. So, when we analyzed, we classified activity into four levels—well, three for now: light, moderate, and vigorous, and, in summary, what we found is that the part of activity that seems to correlate the best with optimal brain glucose metabolism was moderate-intensity physical activity. So, it looked as though light activity is not sufficient to optimize brain glucose uptake and vigorous activity might not be needed.

Chin: So, can you—I don't know if this is possible—but could you define for us what is light activity versus moderate activity versus intense?

Okonkwo: Good question, and that is one that we get quite frequently. I think an easy way to think about this is to think of relative intensity, because when people ask, you know, what is moderate, light or vigorous they don't want to know what it is in the absolute—It's how do I know when I'm engaged in light or moderate or vigorous intensity physical activity? One approach that the field has developed is something called “the talk test.” So, when you are engaged in light physical activity, you can easily talk, and you can easily sing. When you are engaged in moderate physical activity, you can talk, but you clearly cannot sing. On the other hand, when you are engaged in vigorous levels of physical activity. you pretty much cannot say more than a few words without having to pause to catch your breath.

Chin: That's really helpful and I've never actually heard of the talk test before, and in clinic, I'm often explaining maximum heart rate and calculations and using your smart watch to do that. Not everyone has that and you're right everyone cares about what does it mean to me.

Okonkwo: That's right.

Chin: So, this idea that a person—and frankly a lot of my patients are over the age of 80—for them, if they are walking their dog and they can't sing then that could potentially mean moderate physical activity.

Okonkwo: Correct, and that is where the talk test comes in very handy.

Chin: Well, thank you for sharing that.

Okonkwo: Yes.

Chin: So, the other variable, in addition to intensity, is duration, and you comment that it's too early to know what is the exact number, but I think a question that a lot of my patients have is—can that time be broken up throughout the day? Sometimes it's hard to get a 40-minute walk in. Could I do two 20-minute walks? Is that something that your studies either support or have looked at?

Okonkwo: So, I'll begin by saying any activity is better than nothing. The American Heart Association has already published guidelines for what is optimal physical activity for older adults, and, at this point, it is a half hour of that moderate-intensity physical activity for up to five days a week. Now, to come to the question you asked, though again I want to emphasize that any activity is better than nothing, so, someone who is not able to go to the gym for a full hour or a half hour should not ever give up and say well since I can't do a full hour or half hour then what's the point, because anything is better than nothing. Now, to be even more specific, when someone has to break their walks out into what is called bouts, optimally you want to have at least 10 to 15 minutes of bouts. So, if you are able to do 10 or 15 minutes in the morning and 10 or 15 in the afternoon or somewhere in between for a total of 30 or 40 or 50 or 60, wonderful, but even if you can get in only 10 minutes, any activity is better than nothing.

Chin: Now, I saw in a publication of yours from November 2015 you looked at the direct impact of exercise on people's thinking or their ability to take certain tests and you correlated that with whether or not they had beta-amyloid—I was hoping you could talk about that.

Okonkwo: Yes, that actually is one of those pivotal studies that we did. Now, as I mentioned, my work earlier on was focused on trying to understand which of these markers of Alzheimer's best predicts clinical change or cognitive change. At the time, and even to now, there is a big focus on amyloid given that amyloid is what is believed to lie at the outset of progression of Alzheimer's. So, in this study, we did find as expected, that if you look at the group overall, there was an association between the amount of amyloid in an individual’s brain and their rates of cognitive change over time. To me, the what was more interesting, and I think what was the highlight of the study is that when you delve in further and stratify the sample between those who are physically fit and those who are not, we find that this adverse impact of the amount of amyloid in your brain was only seen among those who are physically inactive. When we looked at those who are physically active—who are physically fit—it almost did not make a difference how much amyloid you had in your brain, your thinking skills were just as sharp. So, it's almost like being physically active and physically fit dampens or kind of like tunes off the effects of amyloid on your cognitive function. I think that was phenomenal that was wonderful. That was just wonderful to see, really, because, I mean, you know, if this is something that I can present to a patient that gives hope that even though today it looks like you have your PET scan is showing that there is a good amount of amyloid in your brain, this is not a death sentence. Pretty much there are things that you can do to mitigate the influence of this amyloid on your risk of progression because the amount of amyloid in someone's brain is only worrisome since we know what amyloid does to thinking and it is that effect on thinking that people worry about. You know what happens when I can't remember my children, my spouse, my family—they could care less how much amyloid they have in the brain if there was not that other risk for memory loss. So, if we’re able to show that there is something that you can do that might preserve your thinking, that's huge.

Chin: Yeah, it's very empowering.

Okonkwo: Yeah.

Chin: So, then I guess I'll end by asking what do you tell your friends and your family members who may be concerned about their memory?

Okonkwo: Five simple words: get out and get moving.

Chin: Well, thank you, Dr. Okonkwo, for coming in for today's podcast. We appreciate having you and hope you'll come back again for another conversation.

Okonkwo: Thank you. It’s been a pleasure.

Credits: Dementia Matters is brought to you by the Wisconsin Alzheimer's Disease Research Center. The Wisconsin Alzheimer's Disease Research Center combines academic, clinical, and research expertise from the University of Wisconsin School of Medicine and Public Health, and the geriatric research education and clinical center of the William S. Middleton Memorial Veterans Hospital in Madison, Wisconsin. It receives funding from private, university, state, and national sources, including a grant from the National Institutes of Health for Alzheimer's Disease Centers. This episode was produced by Rebecca Wasieleski and recorded and edited by Alex Wehrli. Our musical jingle is "Cases to Rest," by Blue Dot Sessions. Check out our website at adrc.wisc.edu. You can also follow us on Twitter and Facebook. If you have any questions or comments, email us at dementiamatters@medicine.wisc.edu. Thanks for listening.