Loneliness increases a person’s risk of dementia by 40%, regardless of gender, race, ethnicity, education or whether the individual has regular social contact with friends and family. That’s according to newly released results of a study involving data collected over 10 years from 12,000 people.

“We are not the first people to show that loneliness is associated with increased risk of dementia,” said Angelina Sutin, Ph.D., the study’s principal investigator and an associate professor at the Florida State University College of Medicine in Tallahassee, “but this is by far the largest sample yet, with a long follow-up. And the population was more diverse.”

Results were published in the Journal of Gerontology: Psychological Sciences.

Sutin and co-authors used data from the federally funded Health and Retirement Study, in which participants aged 50 or more years, and their spouses, reported on their loneliness and also underwent a battery of cognitive tests every two years, up to 10 years after their reports of loneliness.

Over the course of the study, dementia developed in 1,104 participants. Participants who reported greater feelings of loneliness were more likely to develop dementia over the next 10 years.

The team defined loneliness as “the subjective experience of social isolation,” which is different from actual social isolation.

“It’s a feeling that you do not fit in or do not belong with the people around you,” Sutin said. “You can have somebody who lives alone, who doesn’t have very much contact with people, but has enough — and that fills their internal need for socializing. So even though objectively you might think that person is socially isolated, they don’t feel lonely.

“The flip side is that you can be around a lot of people and be socially engaged and interactive and still feel like you don’t belong,” she added. “From the outside, it looks like you have great social engagement, but the subjective feeling is that you’re not part of the group.”

The research, Sutin said, “lends credibility to the idea of asking people how they feel about things — in this case, how they feel about their social interactions.” The good news, she said, is that loneliness is a modifiable risk factor.

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