Researchers study possible links to dementia

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.

Researchers are looking at what factors influence a person's risk for dementia. Today, I am talking with a public health and geriatrics researcher from Upstate who has examined how neighborhoods may impact dementia risk.

Dr. Roger Wong is an assistant professor of public health and preventive medicine, and he also has an appointment in the department of geriatrics.

Welcome back to "The Informed Patient," Dr. Wong.

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

Host Amber Smith: Before we get into the study itself, help us understand the measurements you used.

What does "nativity" mean, and why does that matter?

Roger Wong, PhD: For the context of the study, nativity is pretty straightforward. I think it's just whether or not you were born in the United States, and I think it's a really important topic right now because I think we all see the news. Immigration is a pretty hot topic, and it seems like many of these immigrants will be staying in the United States for the foreseeable future.

Host Amber Smith: What is meant by "neighborhood disadvantage"?

Roger Wong, PhD: Neighborhood disadvantage is, I think, a pretty loaded term. A lot of researchers have different definitions of neighborhood disadvantage. Typically, I see in previous research that neighborhood disadvantage is often measured as the percent of people in a specific community that has less than a high school degree, (and) what is the median income of the people in this certain ZIP code?

I think those are valid measures of maybe neighborhood disadvantage, but I mean, from a public health standpoint, I think it's pretty difficult to intervene and enforcing people to get a higher education, get higher incomes, when realistically, this is probably not possible.

So I measure neighborhood disadvantage a little bit differently. I look at it from more of the physical and social side of a neighborhood. I'm looking at things like neighborhood physical disorder, which in this study I define as whether or not the neighborhood has high levels of graffiti, litter and also vacant buildings. So that's the first component of neighborhood disadvantage I look at specifically for physical disorder. And then the second component is, I was looking at neighborhood social cohesion. This is whether or not you know, trust and help people in your neighborhood.

Host Amber Smith: So you really have to be familiar with the neighborhood that you're studying.

Roger Wong, PhD: Yes, and some people often ask me how objective are these measures for physical disorder and social cohesion, which I think is a fair question.

Starting with the physical disorder, I think that's pretty objective, because you have the researcher that goes directly to the community, and they have a pretty standardized questionnaire. They're looking around to see if there's litter, graffiti and also vacant buildings. So it's not from the person that's being interviewed, it's actually the researcher that is assessing this. So I think that's pretty objective.

Whereas, I would admit, obviously the researcher's not going to know how socially cohesive a neighborhood is, so we ask this to the person that's being interviewed.

Host Amber Smith: So tell us about your sample. How many people, and where were they from, that you were looking at?

Roger Wong, PhD: This study, it's funded by the National Institutes of Health, the NIH, and this sample that I was looking at, they're all older adults, 65 years and older. This is all of the United States, except for Hawaii and Alaska. And also, to be eligible for the study, you had to be a Medicare beneficiary, so this is like 99.9% of all people 65 years and older, on Medicare. And I was looking at a sample of 5,000 people. So that's the starting sample size.

And I was looking at 10 years of this dataset, so the first time that this data was collected was in 2011, and then they interviewed these same older adults every single year, so the end cutoff that I used was 2020, and the main reason for that is because there was a pandemic in 2020, so we didn't have a researcher that could go to the community at that year and measure physical disorder because there was a lockdown for many communities.

So in this 10 years of data for 65 years and older, and even though it's 5,000 people in the 48 states, I did something in statistics we call "weighting," where we try to adjust the results to be a little bit more representative of the whole U.S. population, because typically, in these datasets, they don't really interview enough racial and ethnic minorities, and they don't interview enough people in the oldest age groups.

So after I weighted these 5,000 people, these results are actually representing 27 million older adults in the United States, 65 years and older.

Host Amber Smith: Well, one of the things you were looking at is how nativity status is associated with dementia risk.

So what do we already know about this?

Roger Wong, PhD: It's a very complex literature on this topic, and, thankfully, I had a really great student. Daniel (Soong) is my co-author on this paper. He's in his second year in the MD program here at Upstate, and based on his review of the literature, he found that it's really convoluted, because there's kind of half of the literature that says that nativity is not associated with our risk for dementia. And then there's like kind of the other half that's shown that maybe nativity might be protective.

So I'll talk about the first half first. There's one paper that I can think of, I believe it's published from a group in California, and they found that there's basically no association between nativity and dementia. But the California population, when they were looking at non-native, so this is foreign-born older adults, pretty much everyone in that demographic group were Asian older adults. So they were comparing Asian older adults to white older adults. And so they found no association with nativity.

And then the other half, which finds that nativity might be protective, the best example that I can think of is a group in Texas. They found that there's something known as the "healthy immigrant effect," where people with more resources, they're more likely to immigrate into the United States, and as a result, they tend to be a whole lot healthier, and they protect their cognition later on in life because of that.

So this was the case that was talked about in the Texas group, where they found that for their non-native population, which was predominantly Hispanic, they had a protective effect for dementia.

Roger Wong, PhD: As you might be noticing, a huge problem is that the foreign-born older adults in these different studies, it's with just like one single racial/ethnic group. There's so many different racial/ethnic groups within "foreign born." So that's kind of the problem that Daniel and I tried to fix with this study -- or not fix, but contribute, with this study. We want to include multiple racial/ethnic groups for those that were both native and also non-native to the United States.

Host Amber Smith: So if there are papers that show that being foreign born increases your risk of dementia, and other papers that show that it decreases, what did your work show?

Roger Wong, PhD: I had three research questions for the paper that I'm talking about right now. My first research question is, I wanted to see, like, the answer to your question, Amber: What is the association between nativity and dementia risk? So I found that in this 10-year period from 2011 until 2020, those that were foreign born, so born outside the United States, they had a 51% higher risk for dementia by the end of the 2020 period.

Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith.

I'm talking with assistant professor of public health and preventive medicine at Upstate Dr. Roger Wong

You also looked at differences in neighborhoods in their physical disorder and social cohesion. How does this vary based on nativity status?

Roger Wong, PhD: Last year I talked about the preceding study for this, where I was looking at the association between neighborhood physical disorder and social cohesion, how that's linked to dementia risk. The paper that I published a few years ago, I found that those older adults that were living in neighborhoods with more physical disorder, they had an 11% increased risk for dementia later on in life. And this was same dataset, but different years; it was 2011 until 2019. So, nine years of data for that. And then I didn't find a significant association between social cohesion and dementia risk.

Host Amber Smith: Do we know why living in a disadvantaged neighborhood with graffiti and vacant buildings, why does that increase someone's dementia risk?

Roger Wong, PhD: In my 2020 paper, I talked about how the most likely reason is because a lot of these older adults, they don't really feel safe exercising outdoors, and exercise is probably one of the best preventive approaches we can do today to protect our risk for dementia. So that is the main mechanism we talked about in our paper, about how we think living in these neighborhoods with very high levels of physical disorder is increasing our risk for dementia later on in life.

Host Amber Smith: There's got to be stress that goes along with that. If you're living in a place that you're so fearful of, you can't exercise outdoors, what is that stress doing?

Roger Wong, PhD: Yeah, for sure. And there's been quite a few studies also looking at neighborhood levels of stress and how that's been linked to dementia, and I totally agree. I think they go hand in hand with the safety in the neighborhood, the stress and how that's linked with dementia. And so there definitely have been papers that have talked about that mechanism as well.

Host Amber Smith: Well, looking from the other direction, even in a disadvantaged neighborhood, if there's an ethnic enclave of people who really are cohesive, have you seen that that makes a difference in dementia risk?

Roger Wong, PhD: Yeah. And ethnic enclaves is really fascinating to me. I am of Chinese descent, and most of my relatives live in ethic enclaves, so I have a few of my relatives that are living in Chinatown in Manhattan. And then the vast majority of my relatives are living in Flushing, in Queens. And I myself have lived in an ethic enclave. So I lived in Chinatown for at least a year between undergrad and grad school. I was teaching in the Bronx.

I thought it was so cool how it was a really socially cohesive neighborhood in Chinatown, but also it was just like high levels of physical disorder. There's just, like every day, graffiti on my apartment; it got painted over, and then, fresh graffiti the next day. And the sidewalks were really just not great as well. And so, it was really interesting for me to think about how does living in this type of neighborhood impact your health later on in life?

So that was another motivation for this paper I was also writing on nativity and neighborhood and dementia. Like, how does this all come together?

So for this paper that I'm talking about right now, unfortunately, we don't really have any measures of ethnic enclave; this was more of the motivator for the reason why we looked at this. But our theory was that, OK, so even though these immigrants are living in these ethnic enclaves, (with) high levels of physical disorder, the social cohesion, as you noted, Amber, it might protect their cognition later on in life. So that was kind of the original intention of the study, but we didn't answer that question.

So I think that might be the next direction that we want to answer: How does that all come together? Even though you have high levels of physical disorder, but maybe that's balanced with high levels of social cohesion, how does that kind of all fit into this relationship with nativity and dementia?

Host Amber Smith: For this paper, did you look at how a neighborhood could moderate the relationship between nativity status and dementia risk?

Roger Wong, PhD: Yes. I will answer that question, Amber. Maybe I'll talk about my second research question first, and then that moderation is my third research question.

So my second research question is, I wanted to see if there are any differences in physical disorder and social cohesion by whether or not you were born in the United States. I found from my second research question that those that were immigrants had significantly higher levels of physical disorder and also significantly lower levels of social cohesion in their neighborhoods. So this is throughout the whole 10-year period, from 2011 until 2020. So this is like their entire life. It's high levels of physical disorder, high levels and low levels of social cohesion for those that were immigrants, which is really concerning to me.

So that kind of led to my third research question. I found from my first research question that immigrants have a 51% significantly higher risk for dementia. And then I also found from my second research question, we're finding that immigrants are living in these neighborhoods that are more disadvantaged.

So that led to my third research question. OK, so basically, in lay terms, we know that dementia risk is higher for those that are immigrants. How does neighborhood play into this?

So immigrants, if they're living in neighborhoods with maybe high levels of social cohesion, so this is tying it back to, again, the whole ethnic enclave, maybe if they're living in these neighborhoods with high levels of social cohesion, is this protecting their cognition then, later in life?

And likewise, it's the same thing with physical disorder. Maybe if they're immigrants living in neighborhoods with higher physical disorder, maybe it might be further increasing their risk for dementia. So that's kind of what I tried to answer with my third research question.

Unfortunately, I didn't find anything in this third research question. Basically, it didn't seem like neighborhood was kind of explaining the reason why immigrants have a higher risk for dementia. I talk about, in the paper, that the theory that it's probably more due to discrimination that immigrants face on a frequent basis.

And I can see this as well from my parents. They're both immigrants. There's pretty high levels of, unfortunately, high levels of discrimination in the United States, especially when you're interacting with the health care system. So I think that might be part of the reason why immigrants have a higher risk of dementia later in life. It's probably partially due to discrimination and also partially due to stress, being an immigrant and trying to like, navigate this whole U.S. system as well.

Host Amber Smith: Well, let's go over some of the takeaways from your study. What would you like health care workers or health care professionals to be aware of?

Roger Wong, PhD: I think, as we talked about earlier, immigration is a huge issue right now because there's just a lot of folks that are trying to escape countries with sociopolitical unrest, and I think this will continue to be a huge problem in public health. So I think health care professionals should just be cognizant that my findings indicate that foreign-born older adults, they appear to have a significantly higher risk for dementia later in life.

And I think that's something we really need to address early and try to address as soon as possible, because right now, we don't have a cure for dementia. We don't have any definitive approaches to prevent dementia. And once you get dementia, it's really hard to treat it. Your memories won't come back. But with the current treatment methods we have, it's only able to kind of help the condition not get worse -- it's the best way that I can explain it.

So I think we really need to figure out right now and focus on these foreign-born older adults and how we can reduce the risk for dementia.

Host Amber Smith: Is there anything that you would suggest city planners could do regarding neighborhoods? Is there any way to design them or plan for them that would be more beneficial?

Roger Wong, PhD: I wish that we could include more green spaces within these neighborhoods for city planners, but I mean, realistically, I get it. I don't think that is always feasible. I think these findings are more related to have implications for maybe policy makers rather than city planners. Like in the paper I talked about, published in 2020, I was finding that racial/ethnic minorities are significantly more likely to also live in these disadvantaged neighborhoods with high levels of physical disorder, low levels of social cohesion. And then with this paper I'm talking about right now, with immigrants, they're also living in these same conditions of high levels of physical disorder, low social cohesion. So I wish that we could, from a policy standpoint, invest more in these neighborhoods because regardless of these demographic differences, it's clear from many studies, including mine, that these neighborhoods that are not really ideal to, and conducive to, physical activity, it increases their risk for dementia later in life. It's shown from many research studies. So I wish we could invest more in these neighborhoods from a policy standpoint.

Host Amber Smith: Well, Dr. Wong, thank you so much for making time for this interview.

Roger Wong, PhD: Yes. Thank you so much for having me.

Host Amber Smith: My guest has been Dr. 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 goudounet.com/informed.

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