New research from the University of St Andrews has found a direct link between social isolation and faster memory and thinking decline in older adults.
This decline, often caused by Alzheimer’s disease and related types of dementia, appears to happen more quickly in people who are socially isolated—even if they don’t feel lonely.
The study was published in The Journals of Gerontology, Series B, and it’s one of the largest of its kind.
It showed that people who have fewer social connections or activities are more likely to experience a faster decline in cognitive function, the mental skills we need to remember, reason, and make decisions.
Importantly, the researchers found that social isolation and loneliness are not the same. Social isolation is about the number of social interactions a person has—like attending community events, being part of religious groups, or having regular contact with friends and family.
Loneliness, on the other hand, is a person’s own feeling of being alone, regardless of how many people are around them.
This distinction matters because the study found that even people who don’t feel lonely, but are still socially isolated, are at greater risk of their brain health declining. In other words, you can feel okay emotionally but still be missing out on the brain benefits of social connection.
Researchers looked at over 137,000 cognitive tests collected from more than 30,000 people in the U.S. between 2004 and 2018. These tests were part of a national study tracking health and retirement. The findings were consistent across all groups of people, no matter their age, gender, race, or level of education. Everyone seemed to benefit from being more socially connected.
The idea that being socially active is good for health is not new, but this study gives clear scientific evidence that isolation alone can lead to brain decline—even without feelings of loneliness. And that makes prevention more urgent than ever.
This research comes at a time when both social isolation and loneliness are getting more attention from public health experts. Before the COVID-19 pandemic, about one in four older adults already reported feeling socially isolated.
And loneliness has been called a growing public health crisis in many high-income countries like the U.S., U.K., Germany, Sweden, Australia, and Japan.
With nearly 7 million Americans already living with Alzheimer’s disease, and about one in every 11 people over 65 affected in the U.K., finding ways to slow or prevent dementia is vital. Since there is no cure for Alzheimer’s, prevention through lifestyle changes—like staying socially active—could be one of the most powerful tools we have.
Dr. Jo Hale, the lead author of the study, said that holidays often remind us of the importance of being around loved ones. But her research shows that regular social engagement is more than just a feel-good activity—it could help protect the brain.
Dr. Hale urges communities and health systems to help older adults stay socially involved, especially those who may not have nearby family or close friends. Creating more chances for people to connect, through programs, activities, and outreach, could have major benefits for brain health and aging.
If you care about dementia, please read studies that eating apples and tea could keep dementia at bay, and Olive oil: a daily dose for better brain health.
For more health information, please see recent studies what you eat together may affect your dementia risk, and time-restricted eating: a simple way to fight aging and cancer.
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