The Impact of Social Isolation on Dementia Risk in Older Adults

Headshot of Alison Huang
Alison Huang, PhD, MPH

In May 2023, the U.S. Surgeon General, Dr. Vivek Murthy, released an advisory calling attention to the public health crisis of loneliness and social isolation in the U.S. With this widespread issue affecting such a broad population, how does social isolation impact older adults? Dr. Alison Huang joins the podcast to share insights from her study on the relationship between social isolation and the risk of dementia in older adults. Using data from a nine-year National Health and Aging Trends Study (NHATS), she discusses how factors like living alone, limited social networks and reduced activity participation contribute to increased dementia risk.

Guest: Alison Huang, PhD, MPH, senior research associate, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health

Show Notes

Learn more about the U.S. Surgeon General’s 2023 advisory, Our Epidemic of Loneliness and Isolation, on the U.S. Department of Health and Human Services (HHS) website.

Read Dr. Huang’s study, “Social isolation and 9-year dementia risk in community-dwelling Medicare beneficiaries in the United States,” on the Journal of the American Geriatrics Society website.

Learn more about the National Health and Aging Trends Study (NHATS) on their website.

Learn more about Dr. Alison Huang on Johns Hopkins Cochlear Center for Hearing and Public Health’s website.

Learn more about Alzheimer's disease prevention on our website.

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IntroI’m Dr. Nathaniel Chin, and you’re listening to Dementia Matters, a podcast about Alzheimer's disease. Dementia Matters is a production of the Wisconsin Alzheimer's Disease Research Center. Our goal is to educate listeners on the latest news in Alzheimer's disease research and caregiver strategies. Thanks for joining us.


Dr. Nathaniel Chin: Welcome back to Dementia Matters. Today I'm joined by Dr. Alison Huang, a senior research associate from the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health. Dr. Huang works closely with the Cochlear Center for Hearing and Public Health, where her research centers on the epidemiological study of modifiable risk factors for cognitive decline in dementia. She has a special interest in the overlap of social and mental health delving into areas such as social isolation, loneliness, depression, anxiety, and hearing loss. In January 2023, Dr. Huang published a paper in the Journal of the American Geriatric Society using data from a 9 year National Health and Aging Trend Study, which suggests a connection between social isolation and risk of dementia in older adults. Dr. Huang, welcome to Dementia Matters.


Dr. Alison Huang: Thank you, thank you for the invitation.


Chin: I think to begin I'm going to ask that you define a couple terms for us, or at least one of the main terms. How are you looking at social isolation? How are you defining social isolation for this study and how do you measure it?


Huang: Yeah, that's a great place to start. Thinking more broadly, this concept of social connectedness – there's social isolation, which is more of an objective measure of your state of social connectedness. Things like the number of people in your social network or your living situation or your marital status, it's more of those objective measures. There's also a construct called loneliness, which is a subjective measure which is more of the perceived aspect of social connectedness. How often you feel like you lack companionship or whether you feel close to people or not or whether you feel alone. When you think broadly about social connectedness we commonly think about both social isolation, this objective part, and loneliness, which is a more subjective aspect. In this study, we focus more on social isolation and look more at the objective part. In the United States, prevalence of social isolation is high. It's, you know, one in four in older adults report having social isolation and there are many ways to measure social isolation. In this study, we looked at social isolation and this was measured by living situation as well as the number of people in your social network and as well as activity participation. Participants received one point if they did not live alone. They also received one point for having at least two or more people to talk to about important matters with. They also received one point each for past month participation in social activities like volunteer work or clubs, as well as past month participation in religious services. So having a score of zero or one, participants were classified as socially isolated. Having a score of greater than one participants were classified as not socially isolated.



Chin: I think I'll ask you later on a little bit more about your metrics when we talk more about your study, but I really appreciate that definition. I'm seeing more and more the importance of addressing social isolation or talking about social isolation but then I think to myself, well how does one know if they're isolated or not and what if you prefer to not be around as many people. 

Hearing the difference between isolation and loneliness, I think, is really important. How is social isolation, the objective measure, then related to the development of dementia?


Huang: Yeah, and I'll say also that social isolation and loneliness are not mutually exclusive. You know, someone can be socially isolated and lonely, or someone can also have many social connections around them but feel very lonely. There is, you know, quite a difference between the two. And the context of dementia, so the key finding of this study was that, in a large nationally representative study of older adults in the United States, being socially isolated versus not being socially isolated was associated with a 27 percent, so a nearly 30 percent higher hazard or higher risk of dementia over nine years. This is consistent with much of the prior evidence on this association. A report from the Lancet Commission came out in 2020 looking at 12 modifiable risk factors for dementia and social isolation was on that list as a late-life risk factor for dementia.


Chin: And so there is this prior evidence that is showing that social isolation is a risk factor, and then you're now showing it in a pretty large data system. But your study is unique, so if you could comment on how yours is different and how you're adding to the field.


Huang: Yeah, so this study uses data from the National Health and Aging Trends Study, acronymed as NHATS, and NHATS is a really special study. It's, first, nationally representative, which means it took a random sample of older adults who are Medicare beneficiaries and over 65 from all over the United States. It started in 2011. NHATS collects data on their participants every year and continues to do so even now, so we have a large longitudinal data set. When I say nationally representative it means that estimates from NHATS can be extrapolated to the population, the broader population of older adults in the United States, as opposed to some other studies that might only have samples of older adults in a specific geographic population or older adults who have other defining characteristics. For example, like there's a study of just older women or something. NHATS really is, you know, more representative of the broader general population of older adults. NHATS is also great because they really prioritize including older adults in their study that may not be included in other studies, in other epidemiologic studies and may not be represented in estimates from studies. For example, NHATS collects data through home visits. So they'll actually go into the participants' home to do their data collection as opposed to asking participants to come into a clinic. You can imagine by going into a participant's home and bringing the data collection to them it's a lot easier to have participants who may be physically unable to travel to a clinic to participate or who, you know, may not have the transportation to get to a clinic to participate. It really increases the representation of those older adults who may not be represented in other studies that rely on clinic-based visits. NHATS also has an oversample of the oldest old, so older adults 90 years and over who are less represented in other studies, as well as African American older adults. So they really do a good job of, you know, trying to really capture the general population of older adults in the US. And then mentioned previously, NHATS is longitudinal so we have data since 2011, which is another added value of this study that we were able to look at dementia risk over nine years, which many other studies have not been able to do.


Chin: That's incredible. And of course it speaks to the value of a lot of data and a lot of good data over time, and so those participants and NHATS – I mean how incredible that they're willing to do this for such a long period. With that in mind, what types of things did you look at in your study when you were looking at social isolation or maybe even degree of isolation? I know you mentioned a few things in the beginning, but if you could get a little bit more specific.


Huang: Yeah, so in NHATS this measure of social isolation is based on another measure called the Berkman-Syme Social Network Index, which is a structural measure of social isolation. We take into account living situation, social network size, and participation in activities. Pparticipants are given one point for living alone, one point for not having at least two or more people to talk to about important matters with, and one point each for having no past month participation in activities like volunteer work or clubs, and another point for no past month participation in religious activities. Those with points of zero or one were considered isolated, and those greater than one were considered not socially isolated.


Chin: So then with all of that, what did you actually find in your study?


Huang: Yeah, so we actually found that being socially isolated versus not isolated was associated with a 27 percent higher risk of dementia over nine years. So really an almost 30 percent higher risk of dementia.


Chin: And breaking it down a little bit more, not including increased risk, how many people reported being socially isolated? And in this nine year, or whatever the length was that you looked at, how many people actually develop dementia?


Huang: Yeah so 23 percent, so about a quarter were classified as being socially isolated, and of the total number of participants, 20 percent developed dementia by the end of follow up. And that was different by social isolation status. Among those who are socially isolated, 26 percent developed dementia by the end of follow-up versus 20 percent in those who are not socially isolated.


Chin: And did this result differ based on a person's race?


Huang: No, we didn't actually find differences by race. One of the secondary aims of this study was to look at whether the association between social isolation and dementia risk was different by race or ethnicity, and we didn't find differences, suggesting that, you know, this impact of social isolation on dementia is similar across races.


Chin: And then that, of course, gets at the important question of mechanism, or what's actually causing this relationship. Do you – and I know you weren't able to determine that in this study – but do you have ideas what the connection could be between social isolation and dementia?


Huang: Yeah, so there's a couple mechanisms. One is through poor health behavior, so we know that people who are socially isolated tend to have reduced physical activity, tend to be more likely to smoke, have poor diet. This puts these individuals more at risk for other physical and mental health conditions that are associated with dementia risk like cardiovascular disease or hypertension or depression. Additionally, being socially isolated or less connected to the people around you, you know, these older adults may not benefit as much from social resources like social support and information-sharing and care coordination that, on all these factors, contribute to overall health and could also increase risk for dementia and be along that pathway. In terms of the more physiologic, like biologic pathways, we know that social isolation increases stress, and that increased stress response also has negative effects on the brain and brain structure. We also know social Isolation actually has an effect on upregulation of genes that increase inflammation, which is another vascular risk factor for dementia. There's some of these more biological, physiological pathways that could link to dementia. Then in terms of cognitive explanations, people with reduced social engagement and reduced activity, this kind of leans into the cognitive reserve hypothesis. What I mean by cognitive reserve, it's this theory that, you know, with greater cognitive reserve the brain is less susceptible to pathology associated with Alzheimer's and dementia risk. So it can more easily overcome some of those pathologies that can lead to dementia. Ways to increase cognitive reserve are, you know, activity like cognitive stimulation and keeping the brain active. With lower social engagement, without that cognitive stimulation from interacting with other people, could play into not having as much cognitive reserve and leaving the brain a little more vulnerable to neuropathologies associated with dementia risk. These are a couple hypothesized pathways that we think, you know, could explain this relationship that we're seeing between social isolation and dementia.


Chin: Well I must say that was a much greater answer than I was anticipating. There seems to be a lot of connections or potential connections between these and it all makes sense to me. But the biologic, the social aspect, the cognitive reserve. This one area, I mean it shows how important this one area is, but the need to address it as well. My next few questions for you Alison are going to keep in mind what you've done in your research and what you know, and I'm going to ask you to extrapolate to some other things that I've come across in preparing for our conversation. So the US Surgeon General, Dr. Vivek H Murthy, released a report in May of this year, of 2023, on the epidemic of loneliness and the need for social connection in the United States. Not only are these concerns affecting older adults at greater rates, but they're also affecting the majority of the United States population. With what you know, what do you think this means for the future? Do you think this increased social isolation in younger and older groups will contribute to rising rates of dementia over time?


Huang: Yeah that's great, and I'm really glad you asked that question. The Surgeon General has really brought to the forefront this discussion of social isolation and loneliness. And, it's funny, I think every time I turn on NPR, every couple days I feel like I hear a story on social isolation and loneliness. But I think really only time will tell. I think what we know now is that social isolation and loneliness have no real immediate impacts on health and mental health and we see it at every age. I hear a lot about technologies and social media and, you know, teenagers and younger adults and that leading to social isolation. Even though it's a little bit counterintuitive that, you know, maybe feeling more connected through technology but it can also lead to some kind of loneliness. What's great is that with the Surgeon General's work is that he's really bringing social isolation and loneliness into the forefront of the conversation about health. I think previously it was something that is, of course, part of the human experience, but maybe thought of as something that people struggle with singularly or something to not really pay too much attention to or really do anything about. What I really like about his work is that he's bringing this conversation up as something that’s, you know, something that we feel and it's something that we can do to change and really has some impacts to your health and mental health. It's something we should be a little more proactive about and really do some work to address. But I think in terms of dementia risk, I think only time will tell. It's, you know, there's a couple questions to ask there whether it's feeling isolation – the earlier you feel it in your life, does that have an impact – or questions about persistence of loneliness. If you feel it for years or months, years versus more intermittently or more during different phases of your life. You think this gets into some really interesting life course research that could be done. In terms of kind of thinking about what we want to do about it or what we think we can do about it, the good thing about social isolation and loneliness is that it's something we can change. It's a modifiable risk factor for dementia and modifiable at any stage of life, even in late life, vrsus some other risk factors for dementia are not so modifiable, like genetics, like your genes. Or even something like, you know, your level of education, which istypically completed earlier in life and wouldn't be considered maybe a late life, a modifiable late-life risk factor. So the good thing with social isolation is that we can do something about it at every age.


Chin: Well you mention what we can do, and so my next question for you comes because of an NPR article and story. I'm sure we both listened and read the same one. How does technology play a role in social isolation? Can it help people improve their social health, or do you think it might cause more problems than it solves? Just for context, I'm thinking of, there was another study with NHATS that showed that those that had access to cell phones or were using cell phones in a certain way had this reduced risk or had less social isolation among older adults. How do we put these together?


Huang: Yeah, and this was actually a study done by a colleague of mine Dr. Umoh, Mufon Umoh, and she looked at technology use and social isolation and NHATS as well, so same population as the study that we looked at for our paper. She actually showed that older adults with access to technology, so like cell phones, computer, or just, using technology like texting or email, those older adults had lower risk of social isolation over time, which is interesting. I think technology is an interesting one, because, you know, and I think the relationship between technology and social isolation is very different in older adults versus younger adults. For older adults, this work suggests that technology may be a pretty simple way to keep people connected and, you know, really speaks to just different ways especially. I think we all learned during the COVIDpandemic thattechnology can be a great way to stay connected without leaving your home, especially for older adults who, you know, may not be able to travel outside the home to participate in, you know, clubs and groups and things like that. Like, you know, technology may be a simple way to keep people connected in a very good way for older adults to stay connected to family members that don't live in the same area as well. I think there really is some promise and some more research or intervention work to be done around this technology piece in older adults.


Chin: I must say, as someone who's on the computer and cell phone too much, I tend not to think of technology in this regard as a good thing. But here I am talking to you in a different state doing this podcast and I feel social being able to talk to you.I feel conflicted but I appreciate your answer. And really to end, I would like your opinion on how would one go about reducing their risk of social isolation. What should someone do if they feel like they're lonely or socially isolated? What kind of tips or resources would you suggest?.


Huang: Yeah, it's really hard. It's, you know, if you're socially isolated, if you're feeling lonely, that's really hard on your mental health and that can be a real challenge to dig out from and to really feel like you can overcome. At the individual level, you know, the simplest thing is to get out there I think, to join some community programs or clubs or activities. There are programs that pair younger adults with older adults to encourage intergenerational, cross-generational socialization. Tthere are a number of activities or programs that are available to kind of reduce, help reduce social isolation in older adults. I know during COVID there was, I've heard of like check-in lines where people would call older adults just to check in and just to chat. Things like that are activities that people could take advantage of. Another way,on the individual level, is to really address some of the other health risk factors for social isolation. As you mentioned in the introduction, a large part of my work surrounds hearing loss as well, and as you can imagine, having our hearing loss contributes to isolation. With hearing loss it's more difficult to communicate with others, more difficult to understand conversations. It can lead to situations of an older adult with hearing loss sitting at a dinner table surrounded by people but not really engaging or not being able to engage because they can't hear and can't easily engage or understand what's going on. By addressing that hearing loss, for example, through hearing aids, you know – hearing aids can make a world of difference and make it easier to communicate and easier to engage with the world around you. Treating the hearing loss with, for example, hearing aids could potentially really make a difference in terms of social connectedness and even confidence in being able to go out and and socially engage. That's one example, but there's other types of physical and mental health conditions that lead to social isolation. For example, depression or other chronic conditions. Another way is to kind of address those types of factors first that could make it easier to engage to reduce isolation. On the individual level those are, you know, a couple things we can do, but also from you know the broader– I work in public health so I'm always thinking of kind of the broad, what can we do as a society to improve social engagement. I know the Surgeon General has mentioned this as before as well, but there's a lot we can do in terms of making the world a little bit easier for people to gather and connect,  whether that's, you know, public places that people can come together and converse or establishing community programs that can help engage people in certain communities. The healthcare system is also an area, point of care where you know providers could simply ask about social isolation, loneliness and really just have that on their minds as something to consider when talking to patients and link to resources or offer some solutions in that way. There are more kind of systemic public health solutions as well that we could think about, in addition to some of those like individual-level things that a patient or an older adult listening could take on themselves.


Chin: Well, thank you for that because that's a very positive and empowering way of addressing what is, you know, an unfortunate situation of being socially isolated. It seems to me, based on what you've said, there's a lot of opportunities. There's a lot of ways that each individual can address it and certainly, as a society, things that we can all do as a community to prevent or treat social isolation. With that, I'd really like to thank you for being on the podcast, Dr. Alison Huang. It's been great talking to you and I look forward to more of your work. 


Huang: Thank you.


Outro: Thank you for listening to Dementia Matters. Follow us on Apple Podcasts, Spotify, Google Podcasts, or wherever you listen or tell your smart speaker to play the Dementia Matters podcast. Please rate us on your favorite podcast app – it helps other people find our show and lets us know how we are doing. Dementia Matters is brought to you by the Wisconsin Alzheimer's Disease Research Center at the University of Wisconsin--Madison. It receives funding from private, university, state, and national sources, including a grant from the National Institutes on Aging for Alzheimer's Disease Research Centers. This episode of Dementia Matters was produced by Amy Lambright Murphy and Caoilfhinn Rauwerdink and edited by Haoming Meng. Our musical jingle is "Cases to Rest" by Blue Dot Sessions. To learn more about the Wisconsin Alzheimer's Disease Research Center, check out our website at, and follow us on Facebook and Twitter. If you have any questions or comments, email us at Thanks for listening.