Loneliness May Up Alzheimer's Risk

Feb. 5, 2007 -- Lonely individuals are twice as likely to be diagnosed with Alzheimer's disease as those who are not lonely, according to a new study.

Researchers focused on the effects of emotional isolation, or loneliness, in which people perceive themselves as feeling socially isolated and disconnected from others -- sometimes even if they're surrounded by family and friends.

"It turns out people who have this feeling of being socially isolated are at higher risk of developing Alzheimer's," says David A. Bennett, MD, co-author of the study and director of the Rush University Medical Center Alzheimer's Disease Center in Chicago.

Though a small social network of friends and family has been linked in previous research to a higher risk of Alzheimer's, Bennett's group focused on a person's perception of being alone, regardless of their social network size.

"We are talking about a tendency to feel isolated and alone in the world," he says. "You can have a small network and not feel isolated; or you can have a large network but don't know how to connect, and feel isolated."

The Study

Bennett and his colleagues recruited 823 people (average age: nearly 81) in and near Chicago.  All were free of dementia at the start of the study.

Participants had agreed to donate their brains at death to the Rush Memory and Aging Project.

The researchers assessed loneliness using a five-item questionnaire in which participants agreed or disagreed with statements that they didn't have enough friends, often felt abandoned, or experienced a sense of emptiness. They repeated the test annually.

A score of 5 indicated the most loneliness. At the start, the participants' average score was 2.3.

76 Developed Alzheimer's

During the follow-up of nearly four years, 76 participants developed Alzheimer's.

When the researchers looked at the scores of those with Alzheimer's, they found risk of the disease was more than double for those who had loneliness scores of 3.2 (landing them in the bottom 90th percentile) compared with those who were not lonely and had an average score of 1.4 (in the top 10th percentile).

The link between loneliness and Alzheimer's was there, Bennett says, even when they adjusted for small social network and infrequent socializing, both known risk factors.

However, when they autopsied the brains of 90 people who died during the study, they didn't find a link between high loneliness scores and the physical brain changes that point to the disease.

Though loneliness increased the chances of getting a clinical diagnosis of Alzheimer's, it didn't seem to increase the physical brain changes tied to the disease and seen at autopsy.

More research is needed to figure out exactly how loneliness boosts the risk of Alzheimer's, Bennett says.

"The loneliness is doing something to the brain," he says. It may be that it lowers your brain reserve, setting you up for memory problems.