The largest U.S. study about loneliness has found that this condition increases a person's risk of dementia by 40 percent.
A study recently published in the Journals of Gerontology involved 12,030 participants over a period of 10 years. Researchers at the Florida State University (FSU) College of Medicine found the risk applies to all demographics, including gender, race, ethnicity or education.
Researchers studied data collected as part of the University of Michigan's Health and Retirement Study of Americans 50 years and older, and their spouses. The study was sponsored by the National Institute on Aging and the Social Security Administration.
We aren't the first people to show that loneliness is associated with increased risk of dementia, said Dr. Angelina Sutin, principal investigator on the study. She is also an associate professor in FSU's Department of Behavioral Sciences and Social Medicine. She said this is by far the largest sample yet, with a long follow-up. And the population was more diverse.
Participants explained their loneliness and social isolation. They were administered a cognitive battery every two years up to 10 years after their reports of loneliness. During the study, 1,104 people developed dementia.
People who feel lonely are likely to have several risk factors for dementia, according to the study. These include diabetes, hypertension and depression. In addition, lonely people are likely to be physically active and more likely to smoke. Loneliness still predicted dementia even after adjusting for those risks, said the study.
Researchers defined loneliness as the subjective experience of social isolation. This is separate from actual social isolation. Loneliness has also been defined as a complex and often unpleasant emotional response to isolation. Loneliness is prevalent throughout society.
Loneliness is a feeling that you don't fit in, or don't belong to the people around you, said Sutin. She noted 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 one might think that person is socially isolated, he or she doesn't feel lonely. On the other hand, a lot of people can be socially engaged and interactive, and still feel like they don't belong. The subjective feeling is that not part of the group said Sutin.
Sutin said loneliness can have specific physical effects. Among these effects are higher or longer-lasting inflammation, which can have other negative effects on health. Inflammation can lead to behaviors such as heavy drinking or being sedentary that can damage the brain and a lack of meaningful interaction that can lead to cognitive health problems.
