December 24, 2025
Two new studies underscore the importance of social interaction in helping to keep the brain in good working order as we age. The findings add to growing evidence that staying socially engaged may help to delay or ward off the onset of Alzheimer’s disease and other forms of dementia late in life. They should also encourage all of us to reach out to friends and neighbors this holiday season to help keep the communal spirit alive and well.
The first study, from researchers at the University of St. Andrews in Scotland and other institutions, found there may be a direct link between social isolation and a more rapid decline in thinking and memory skills later in life. The study found that greater degrees of social isolation were consistently linked to faster rates of cognitive decline as people age, regardless of whether they feel lonely or not.
The researchers analyzed data from more than 30,000 older Americans who were part of the long-running U.S. Health and Retirement Study. They assessed how socially engaged study participants were by such measures as how often they saw friends and family, whether they lived with a spouse or partner, membership in community organizations or church groups, volunteer activities, and whether they felt they have someone to confide in. Participants also underwent regular tests of memory and thinking skills taken between 2004 and 2018.
They found that regardless of such factors as gender or level of education, social engagement appeared to protect the brain against cognitive decline. Social interaction appeared to provide benefits for brain health regardless of whether someone reported feeling lonely or not.
“Around the holidays, many of us think a lot about how important it is to be surrounded by family and friends,” said Jo Mhairi Hale, the study’s lead author and a senior lecturer at St. Andrews. ”From Pagan winter holidays to classic Christmas tales, we’re reminded that social engagement is good for our mental health. This research shows that it’s also important for our cognitive health.” Dr. Hale emphasized that encouraging social interaction should be a priority for all of us this holiday season, especially those who might not have family or friends nearby.
The second study, from researchers at the University of New South Wales in Sydney, Australia, looked at 851 men and women aged 70 and older who were part of the long-running Sydney Memory and Ageing Study. Researchers used psychological tests to measure a factor known as “social frailty,” which indicates how socially isolated someone might be.
“Social frailty is when we are vulnerable to losing the resources we need to stay socially connected and to fulfil our social needs,” said study author Suraj Samtani, a clinical psychologist and researcher at UNSW Sydney’s Centre for Healthy Brain Aging. Participants also underwent tests of memory and thinking skills over a 12-year follow up period.
The study found that “socially frail” individuals were about 47 percent more likely to develop Alzheimer’s disease or other forms of dementia than their socially connected peers, even after accounting for other factors such as physical and psychological frailty.
“In midlife, risk factors like hearing loss and metabolic syndromes like hypertension and diabetes are very important to prevent and manage,” Dr. Samtani said. “But in late life, social isolation is the biggest risk factor for dementia.”
The findings underscore the importance of enhancing or maintaining social skills and connects as we age. “When thinking about social interactions, we encourage people to think about something they care about or enjoy,” Dr. Samtani said. “They could volunteer, join a book club, a community class where they do activities together, or a dance group.”
Both studies were published in The Journals of Gerontology, Series B: Psychological Sciences and Social Sciences.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Sources: Jo Mhairi Hale, PhD; Angelo Lorenti, PhD; Solveig A. Cunningham PhD: “Disentangling social isolation, loneliness, and later-life cognitive function for older adults in the United States: Evidence from causal inference modeling.” The Journals of Gerontology Series B, December 16, 2025
Annabel P. Matison, PhD; Suraj Samtani; Henry Brodaty; et al: “How well do social frailty indices predict incident dementia in older adults?” The Journals of Gerontology Series B, Psychological sciences and social sciences. September 25, 2025
