, new research suggests. Results from a longitudinal study that included more than 5,000 United States–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, 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,” Dr. Cudjoe added.
The findings were published online 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 noted.
Although prior studies have pointed to an association between socially isolated older adults and increased risk for incident dementia, no study has described this longitudinal association in a nationally representative cohort of U.S. seniors.
Dr. Cudjoe said 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 added.
They turned to 2011-2020 data from the National Health and Aging Trends Study, a nationally representative, longitudinal cohort of U.S. Medicare beneficiaries. The sample was drawn from the Medicare enrollment file and incorporated 95 counties and 655 zip codes.
Participants (n = 5,022; 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 wrote. 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 noted.
They added 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.