Social Isolation Hikes Dementia Risk in Older Adults

Batya Swift Yasgur, MA, LSW

January 17, 2023

Social isolation in older adults increases the risk for developing dementia, new research suggests.

Results from a longitudinal study that included more than 5000 US-based seniors showed that nearly one quarter were socially isolated.

After adjusting for demographic and health factors, social isolation was found to be associated with a 28% higher risk for developing dementia over a 9-year period compared with non-isolation. In addition, this finding held true regardless of race or ethnicity.

"Social connections are increasingly understood as a critical factor for the health of individuals as they age," senior study author Thomas K.M. Cudjoe, MD, Robert and Jane Meyerhoff Endowed Professor and assistant professor of medicine, Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, Maryland, said in a press release.

"Our study expands our understanding of the deleterious impact of social isolation on one's risk for dementia over time," Cudjoe added.

The findings were published online January 11 in the Journal of the American Geriatric Society.

Upstream Resources, Downstream Outcomes

Social isolation is a "multidimensional construct" characterized by factors such as social connections, social support, resource sharing, and relationship strain. It also affects approximately a quarter of older adults, the investigators note.

Although prior studies have pointed to an association between socially isolated older adults and increased risk for incident dementia, no study had described this longitudinal association in a nationally representative cohort of US seniors. 

Cudjoe told Medscape Medical News he was motivated to conduct the current study because he wondered whether or not older adults throughout the United States were similar to some of his patients "who might be at risk for worse cognitive outcomes because they lacked social contact with friends, family, or neighbors."

The study was also "informed by conceptual foundation that upstream social and personal resources are linked to downstream health outcomes, including cognitive health and function," the researchers add.

They turned to 2011-2020 data from the National Health and Aging Trends Study (NHATS), a nationally representative, longitudinal cohort of US Medicare beneficiaries. The sample was drawn from the Medicare enrollment file and incorporated 95 counties and 655 zip codes.

Participants (n = 5022; mean age, 76.4 years; 57.2% women; 71.7% White, non-Hispanic; 42.4% having more than a college education) were community-dwelling older adults who completed annual 2-hour interviews that included assessment of function, economic health status, and well-being. To be included, they had to attend at least the baseline and first follow-up visits.

NHATS "includes domains that are relevant for the characterization of social isolation," the investigators write. It used a typology of structural social isolation that is informed by the Berkman-Syme Social Network Index.

Included domains were living arrangements, discussion networks, and participation. All are "clinically relevant, practical, and components of a comprehensive social history," the researchers note.

They add that individuals classified as "socially isolated" often live alone, have no one or only one person that they can rely upon to discuss important matters, and have limited or no engagement in social or religious groups.

Social isolation in the study was characterized using questions about living with at least one other person, talking to two or more other people about "important matters" in the past year, attending religious services in the past month, and participating in the past month in such things as clubs, meetings, group activities, or volunteer work.

Wake-Up Call

Study participants received 1 point for each item/domain, with a sum score of 0 or 1 classified as "socially isolated" and ≥ 2 considered "not socially isolated." They were classified as having probable dementia based either on self-report or lower-than-mean performance in ≥ 2 cognitive domains, or a score indicating probable dementia on the AD8 Dementia Screening Interview.

Covariates included demographic factors, education, and health factors. Mean follow-up was 5.1 years.

Results showed close to one quarter (23.3%) of the study population was classified as socially isolated, with one fifth (21.1%) developing dementia by the end of the follow-up period.

Compared with non-isolated older adults, those who were socially isolated were more likely to develop dementia during the follow-up period (19.6% vs 25.9%, respectively).

After adjusting for demographic factors, social isolation was significantly associated with a higher risk for incident dementia (hazard ratio [HR], 1.33; 95% CI, 1.13 - 1.56). This association persisted after further adjustment for health factors (HR, 1.27; 95% CI, 1.08 - 1.49). Race and ethnicity had no bearing on the association.

In addition to the association between social isolation and dementia, the researchers also estimated the cause-specific hazard of death before dementia and found that, overall, 18% of participants died prior to dementia over the follow-up period. In particular, the social isolation-associated cause-specific HR of death before dementia was 1.28 (95% CI, 1.2 - 1.5).

Cudjoe noted that the mechanism behind the association between social isolation and dementia in this population needs further study.

Still, he hopes that the findings will "serve as a wake-up call for all of us to be more thoughtful of the role of social connections on our cognitive health."

Clinicians "should be thinking about and assessing the presence or absence of social connections in their patients," Cudjoe added.

"Instrumental Role"

Commenting for Medscape Medical News, Nicole Purcell, DO, neurologist and senior director of clinical practice at the Alzheimer's Association, said the study "contributes to the growing body of evidence that finds social isolation is a serious public health risk for many seniors living in the US, increasing their risk for dementia and other serious mental conditions."

Purcell, who was not involved with the study, added that "healthcare systems and medical professionals can play an instrumental role in identifying individuals at risk for social isolation."

She noted that for those experiencing social isolation, "interaction with healthcare providers may be one of the few opportunities those individuals have for social engagement; [so] using these interactions to identify individuals at risk for social isolation and referring them to local resources and groups that promote engagement, well-being, and access to senior services may help decrease dementia risk for vulnerable seniors."

Purcell added that the Alzheimer's Association offers early stage programs throughout the country, including support groups, education, art, music, and other socially engaging activities.

The study was funded by the National Institute on Aging, National Institute on Minority Health and Health Disparities, and Secunda Family Foundation. The investigators and Purcell have reported no relevant financial relationships.

J Am Geriatr Soc. Published online January 11, 2023. Abstract

Batya Swift Yasgur MA, LSW, is a freelance writer with a counseling practice in Teaneck, NJ. She is a regular contributor to numerous medical publications, including Medscape and WebMD, and is the author of several consumer-oriented health books as well as Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom (the memoir of two brave Afghan sisters who told her their story).

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