Researcher probes possible risk for seniors

Host Amber Smith: Upstate Medical University in Syracuse New York invites you to be "The Informed Patient" with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith. Older adults who frequently report sleep disturbances may have an increased risk of developing dementia. That was one finding in research that was recently published in the American Journal of Preventive Medicine. Here to talk about that research is Roger Wong. He's the author of that study, and he's an assistant professor of public health and preventive medicine at Upstate. Welcome to "The Informed Patient," Dr. Wong.

Roger Wong, PhD: Thank you for having me, Amber.

Host Amber Smith: Do I understand correctly that researchers were already aware of a link between sleep disturbance and cognitive impairment, and you set out to look more closely at that?

Roger Wong, PhD: Yeah. We've kind of known about this for several years. But, last year when I was looking at the literature on the link between sleep disturbances and cognitive impairment, I had noticed there's a few problems with the current research on the topic. The first issue is that a lot of this current research is cross-sectional, which means that typically it's just looking at one year of data. So you're not really sure if it's the sleep disturbances that are causing the dementia, or maybe it's the dementia that's causing the sleep disturbances. So that's one problem.

And then the second problem, also, is that I noticed that a lot of this research is looking specifically at specific geographic regions. So for instance, there's one study I saw that was in Baltimore. There was another study in San Francisco, et cetera, et cetera. So it was a lot of city-specific research. But I noticed that there wasn't any research that both had, looking at long-term data -- longitudinal data is what we call it in research -- and also I didn't see any study that used a national sample. So that is the reason why I decided to investigate this.

Host Amber Smith: Interesting. So did you set out, did you have a hypothesis? Did you have something in mind that you thought you would find?

Roger Wong, PhD: Based on the current evidence, I pretty much expected that if they had any sort of sleep disturbances, that would increase their risk for dementia. And so, the three specific types of sleeping services that I looked at were sleep initiation insomnia. So that's defined as if they have trouble falling asleep within the first 30 minutes of hitting their pillow. And then the second type is sleep maintenance insomnia. So that is when, like if you wake up at night, but then you can't fall back asleep. And then the third sleep disturbance I looked at is sleep medication usage.

Host Amber Smith: So how many people were in your study?

Roger Wong, PhD: This is actually a study that's funded by the NIH, which stands for the National Institutes of Health. And this is a national sample of older adults who specifically, they have to be Medicare beneficiaries, so they're 65 years and older. And they started collecting this data in 2011, and then they interview these respondents in person every single year since 2011. So it's really neat to see and track their changes in their health.

And for me, it's really neat to track how quickly they develop dementia based on whatever sort of lifestyle behaviors. So for me, in the study, I was focusing on sleep disturbances. In that study, I think it was only 6,000 people that were in my sample. But this is nationally representative, so that means that this is representing every single state in the United States except for Hawaii and Alaska. Typically for national studies, there's underrepresentation of both racial and ethnic minorities, and also those are like the oldest age groups. So what's neat about the data I was looking at is that they over sampled both of those groups so that they're more represented in the study.

Host Amber Smith: Let's talk about what you found: a 51% increased dementia risk in those who had trouble falling asleep, but a 40% decreased dementia risk in those who would wake up early and then have trouble going back to sleep. Can you explain that?

Roger Wong, PhD: Actually, I think before I continue, I should probably also note that I am -- I will fully admit that I am by no means -- not a sleep researcher. I am a prevention scientist, so I am very interested in finding ways that we can best prevent dementia. And so specifically I look at modifiable lifestyle behaviors such as physical activity, social contacts, substance use.

So the current focus of this now is sleep disturbances, which is one of the modifiable lifestyle behaviors to prevent dementia. So this is actually my very first paper and study looking at sleep research.

Going back to your question, I did find in my research that those that had sleep initiation insomnia, which again, is if you have trouble falling asleep within the first 30 minutes, those people that had sleep initiation insomnia had about 51% significantly higher risk for developing dementia through the 10-year window of the study. I'm not sure if I mentioned the end year was 2020, but I looked at a 10-year window. That's pretty consistent with a lot of the research out there that's currently looking at this topic.

And then regarding the sleep maintenance insomnia, so again, that's if you wake up at nighttime, but then like you can't fall back asleep, yes, you're right, I did find pretty substantial evidence that if you had more frequent sleep maintenance insomnia, you had about a 40% decreased risk for dementia over time. And that finding is kind of interesting because there's some research that shows sleep maintenance insomnia increases dementia risk, other research that shows that there's no association, and then there's other research that shows there's actually -- same thing as me -- sleep maintenance insomnia increases; dementia risk decreases.

So fortunately, there's been two recent studies that I can think of that found the same exact finding as me. One of them was using a different national sample of older adults. And then there's another national study that was -- I think it was done in Norway -- they also saw that people with sleep maintenance insomnia had a significantly decreased risk for, I think they were looking at cognitive impairment, not dementia specifically. It's really kind of reassuring for me to see that although I was really perplexed by this finding, it seems to actually be consistent with actually the most recent research looking at this.

And I talked about, in the paper, that I think that this might be due to something known as the cognitive reserve. Cognitive reserve is very, you can think of it as something like brain plasticity and brain resiliency. You can't really measure cognitive reserve, but oftentimes, ways that we can increase our cognitive reserve to prevent dementias through cognitively stimulating activities.

So for instance, what really prompted this whole study was actually my father. Right when the Covid-19 pandemic started, he started having sleep maintenance insomnia. So he was waking up at night, and he couldn't fall back to sleep. I was very worried about how this would affect his future cognitive risk, right? What's neat about my job is that I can look at the data and do this myself and find the answers to questions I have.

And so, as I mentioned, my father has sleep maintenance insomnia, and I found in my research that people with sleep maintenance insomnia have a significantly lower risk for dementia. So my theory is that I'm thinking the people that wake up at night and can't fall back to sleep, they're not just sitting there, right? They're actually engaging in activities that are stimulating their brain. So giving the example from my father, yes, he's waking up at nighttime, but he's actually doing activities such as reading the newspaper. Most often, he's actually in the garden gardening. I mean, this is like four in the morning. There's like some light. So he's actually engaging in activities that might be increasing his cognitive reserve in the long term and decreasing his risk for dementia.

Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith. My guest is Dr. Roger Wong, an assistant professor of public health and preventive medicine at Upstate, and we're talking about research he did recently into the connection between sleep disturbances and cognitive function.

You also found that people who use sleep medications had a 30% increased dementia risk. Do you think something about the medications affects cognition?

Roger Wong, PhD: Yes. There's been quite a bit of research also discussing the mechanism and how sleep medications increase dementia risk. What's kind of the forefront of the theory is that there's certain classes of sleep medications that are what we call anticholinergic.

So, basically they kind of disrupt a neurotransmitter called acetylcholine in our brain, which is really important for learning and memory. And so that's kind of the proposed mechanism in how using certain sleep medications may increase our risk for dementia in the long term.

Host Amber Smith: Some people take medication to help them sleep, and some people take medication that causes drowsiness as a side effect. Did you differentiate between the two?

Roger Wong, PhD: That's a good question. So again, these sleep questions are asked every single year from 2011. And I was analyzing the data in 2021. So up until 2020, the question for sleep medication, I believe, is something like, "do you use medications to help you fall asleep?" So it didn't differentiate between using medications for drowsiness. This question is more directed at sleep aids. Like, "do you use medications to help you fall asleep?"

Host Amber Smith: Why are racial and ethnic minorities at higher risk of developing dementia than the population at large?

Roger Wong, PhD: That is a separate area of my research. So, I mean, one area of my research I look at ways that we can prevent dementia. And then a second area of my research -- and probably this is actually where I spend most of my time -- is looking at racial and ethnic disparities in dementia risk.

So it's well known in the dementia literature that racial and ethnic minorities have a significantly higher risk for dementia. So specifically, for black older adults, they have about a two times significantly higher risk for dementia. And then for Hispanic older adults, typically the literature says that they have about a 1.5 times significantly higher risk for dementia. And a lot of this is related to something in public health, what we call social determinants of health. So these are oftentimes factors really outside of the individual. For instance, I had a paper I published that I found that racial ethnic minority older adults are more likely, significantly more likely, to live in neighborhoods with higher physical disorder and lower social cohesion. And I found that this might be the reason why it's kind of driving the disparities in dementia risk in later life for racial ethnic minorities.

Host Amber Smith: So disorder would be litter, graffiti, rundown neighborhood, sort of?

Roger Wong, PhD: Yeah. So the three measures that I was looking at, so again, this is actually the same data set that I was using for the sleep dementia paper. And I don't necessarily remember my, I think it was just 2011 through 2019, so it's nine years of data. And the questions about the physical disorder, it's litter, graffiti, and I think the third one is vacant buildings. So I found that if in 2011, the very first year in which that data was collected, if you were living in neighborhoods with higher levels of physical disorder, you had an 11% significantly higher risk for dementia. That's like the first year of the study.

But then I was also interested in, OK, so like later on, by like 2019, when you may have dementia, what is your physical disorder then? Does that also, is that significantly associated with dementia risk too? And it is. So later in life, if you're living in neighborhoods with more physical disorder compared to 2011, you also had a 10% significantly higher risk for dementia.

Host Amber Smith: Now you're not a medical doctor. You're a gerontologist working in public health. One of your research interests you mentioned is modifiable lifestyle behaviors that can help prevent Alzheimer's and related diseases.

What are the most promising modifiable lifestyle behaviors that you see some promise with, that might have an impact on reducing a person's risk?

Roger Wong, PhD: The common ones that are on the list are typically engaging in physical activity, social contact, so this is like interacting with other people. Diet has also been strongly linked to dementia risk, and as we've talked about earlier in the podcast, sleep is emerging in this field because it's a modifiable lifestyle behavior as well. So that's kind of now being included more often on the list as well, if you ever Google "best ways to prevent dementia."

Host Amber Smith: You attended Cornell for your undergraduate degree. How did you decide to study neurobiology?

Roger Wong, PhD: It's a long story, but both of my parents immigrated to the United States, and as a result, they typically were not really around during my childhood. And I was raised by, primarily, my grandparents. So, similar to a lot of other gerontologists, I ended up in the field of gerontology because of my grandparents. They were kind of really the foundation of my childhood because they were my primary caregivers since my parents weren't really around that much. And, it was especially my grandmother that was really, I felt like she was like the centerpiece to our whole family.

And, it was around my last year in high school that my grandmother fell down the stairs, and we later found out that it was because she was starting to develop symptoms from Parkinson's disease. So she was having a lot of difficulty trying to be able to, like her brain was kind of not linking with her legs to work properly. And so I remember in my last year in high school, I was just so surprised how little we knew about not only Parkinson's, but other neurodegenerative diseases. And so that is kind of the reason why I decided to study neurobiology when I did my undergrad at Cornell. And kind of later on I eventually decided to study Alzheimer's disease too.

Host Amber Smith: Well, you mentioned your dad before and his insomnia issues. Is he doing okay?

Roger Wong, PhD: So he still has sleep maintenance insomnia. Again, that's waking up at nighttime and not being able to fall asleep. He was kind of really the motivation to this paper because there was just inconclusive evidence, right? So, it's kind of reassuring to me, at least, that even though he has sleep maintenance insomnia, this may not necessarily increase his risk for dementia, and in fact, it might be a protective effect. I haven't really intervened that much because I am well aware that as we grow older, there are changes in our sleeping patterns, that is often associated with retirement. So I haven't intervened quite yet until I see more evidence that sleep maintenance insomnia may increase a risk for dementia, or other negative health outcomes.

Host Amber Smith: Well, I appreciate you making time for this interview, Dr. Wong.

Roger Wong, PhD: Yeah. Thank you for having me here.

Host Amber Smith: My guest has been Roger Wong. He's an assistant professor of public health and preventive medicine at Upstate. "The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe. Find our archive of previous episodes at Upstate.edu/Informed. This is your host, Amber Smith, thanking you for listening.