Connecting Lifetime Stress to Brain Health

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, I'm talking with Dr. Megan Zuelsdorff, an Alzheimer's disease researcher at the University of Wisconsin whose work focuses on the connection between lifetime stresses and cognitive health. Earlier this year, she presented her findings at the Alzheimer's Association international conference in London. I think it's very relevant research for our community and we're excited to learn more about it today. So, with that, we'd like to welcome Dr. Megan Zuelsdorff to Dementia Matters.

Zuelsdorff: Thank you for having me.

Chin: At this Alzheimer's Association international conference, you presented pretty groundbreaking information, or, at least, very needed information. I know that you've given lots of talks since then, but I was hoping you could sort of expand on what it is that your particular study found.

Zuelsdorff: Sure, it's preliminary research. So, this was done in a relatively large dataset when you're talking about non-Hispanic white participants, but we had a relatively small group of African American participants. So, certainly, we need to replicate these findings before it can make really strong claims, but what I did is look at racial disparities—African-American and non-Hispanic white disparities—that we do see in our Wisconsin Registry for Alzheimer's prevention cohort. I looked at the relationship between lifetime stressful experiences, so just experiences that people reported having across their life course. We asked about 27 different events—things like having a parent who drank so much that it caused problems, during childhood being expelled from school, going through bankruptcy, experiencing the death of a child. So, really adverse and challenging events that people could potentially experience. I looked at the contribution of those events to cognitive health in our entire sample. Then, I also looked at the contribution of stressful events to the racial disparities that we see in cognitive health. I was surprised by the strength of the findings, given the small sample of African Americans that we had. What I found, overall, was that stressful events were associated with poor cognitive health for everybody and that wasn't surprising to me. I've looked at different kinds of stress that we measure in the Rapp study and found that, indeed, it is negatively associated with cognitive function, particularly executive functions—so, planning, problem-solving flexibility, and adapting and processing new information. What I also found, though, is that, first of all, African Americans were much more likely to experience these stressful events than our non-Hispanic white participants. On average, they experienced 60% more of the events over their life course. So, there was this differential exposure which is important given that there's a negative association between stressors and cognitive health for everyone. What I also found, though, is that there was what I'll call a differential vulnerability—so, the relationship between stressors and cognitive function in African Americans was actually exacerbated compared to the relationship for non-Hispanic white participants. That was the more surprising finding. So, you know, we kind of see that there's not only a differential exposure but then also this differential impact of lifetime stressors on cognition and African-Americans.

Chin: When you speak of impacts, I believe your study even gave a number as to what a stressful event can do to the brain.

Zuelsdorff: What I actually did is look at the relationship between age and cognitive health, as to stress and cognitive health, and what we saw is that in African Americans each stressful event was equivalent to four years of chronological aging. If you take two identical people, but one person has experienced one of these stressful events and one person has not, the person who has experienced a stressful event will look like someone else who is four years older. Identical in every other way, but four years older, and that gets to be a big deal when you're talking about sort of accelerated declines that you start to see over the aging process. Four years can make a big difference.

Chin: Absolutely, and frankly, as a geriatrician in my clinic, I often tell patients we are not our age. The chronologic age doesn't reflect the biologic age and we have plenty of people running marathons in their 80s, just like we have plenty of 40-year-olds who can't run a block. So, what you're telling me supports what I've been saying to people, which is that it is our life experiences really do impact us biologically.

Zuelsdorff:  Absolutely.

Chin: It seems to me this is the beginning of something very important, as far as brain aging—as far as aging in general.

Zuelsdorff: We are really excited to expand this research to understand the relationship. As I said earlier, you know it's really clear that this isn't a biological difference that we're seeing. It really is a matter of experience and, certainly, these findings are applicable for persons across racial and socio-economic strata that might be experiencing an undue burden of challenges.

Chin: You've mentioned that you are conducting a larger study.

Zuelsdorff: Yes, we do want to follow these external stressors down under the skin and under the skull. Almost more importantly to me though, we're also going to be collecting information not only on stressors in people's lives, but also on coping strategies that people use and resources that people have available to them, because, of course, what we ultimately want to do is think about stress as a modifiable risk factor. Then look at what characteristics do people have that give them resilience to the negative cognitive effects of stress. Not everyone who's experienced stress is experiencing poor cognition and we want to look at, you know, what protects you—there are social resources, there are social networks, there are social interactions. Are there personal characteristics of coping skills that are helpful? It's going to be really important, I think, to look at those factors and then look at, most importantly, those factors in different populations that are particularly vulnerable that we might want to target interventions for. So, that's where I’m ultimately going. I don't think there's any point in researching stress and talking to people about it if we're not also talking to them about what we can do to protect ourselves and the resources that we can put into place in communities to help out.

Chin: That's excellent, I think that's what the community members want to know. You have identified something that's very significant—stress and its relationship to the aging brain, to cognition. Until your future study results come out, are there things that you would recommend as far as stress reduction?

Zuelsdorff: It's a particular passion of mine and I spent a lot of my training years focusing on positive associations between social engagement and cognitive function. I think there's a lot of evidence that your social networks can help buffer the stress that you might be experiencing. I think that relaxing and meditating and physical activity both have direct impacts on cognitive health, but then they might also buffer negative impacts of stressful events if they help you cope with the challenges in your life. So, I think that all of these things can be beneficial in terms of negative biological impacts of stressful experiences.

Chin: Well I love hearing that, because part of my plan with all of my patients in my clinic is to socialize, is to engage in the community, to exercise, not only for the obvious benefit of those activities, but for this idea that it could be reducing stress, and now we're showing that stress could be a factor of cognitive aging. People want to know why we should do certain things and I think you're starting to prove and show evidence for that.

Zuelsdorff: I think that the underlying message is that there are so many things that are helpful. That you just want to stay engaged in life—and whether that's physical, or it's social, or it's cognitive. I think that all of those things are probably providing independent benefit and certainly that's relevant for any kind of association that we're seeing for stress and health.

Chin: Well, that's wonderful, and thank you for joining us today on dementia matters. We appreciate having you and would love to have you again after your next study is concluded.

Zuelsdorff: Thank you for having me.

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.