Loneliness is transmittable from person to person, study finds

By Rob Stein
Washington Post Staff Writer
Tuesday, December 1, 2009

Loneliness is like a disease -- and what's worse, it's contagious.

Although it may sound counterintuitive, loneliness can spread from one person to another, according to research being released Tuesday that underscores the power of one person's emotions to affect friends, family and neighbors.

The federally funded analysis of data collected from more than 4,000 people over 10 years found that lonely people increase the chances that someone they know will start to feel alone, and that the solitary feeling can spread one more degree of separation, causing a friend of a friend or even the sibling of a friend to feel desolate.

"Loneliness can be transmitted," said John T. Cacioppo, a University of Chicago psychologist who led the study being published in the December issue of the Journal of Personality and Social Psychology. "Loneliness is not just the property of an individual. It can be transmitted across people -- even people you don't have direct contact with."

Moreover, people who become lonely eventually move to the periphery of their social networks, becoming increasingly isolated, which can exacerbate their loneliness and affect social connectedness, the researchers found.

"No man is an island," said Nicholas A. Christakis, a professor of medicine and medical sociology at Harvard Medical School who helped conduct the research. "Something so personal as a person's emotions can have a collective existence and affect the vast fabric of humanity."

The seemingly paradoxical finding is far more than a psychological curiosity. Loneliness has been linked to a variety of medical problems, including depression, sleep problems and generally poorer physical health. Identifying some of the causes could help reduce the emotion and improve health, experts said.

"Loneliness is more than just feeling bad," said Chris Segrin, a professor of communication and health at the University of Arizona, who was not involved in the research. "It really does have consequences."

But some researchers expressed skepticism about the findings, saying the study had the same shortcoming as the earlier work and could not necessarily rule out other explanations for the apparent association.

"It is unclear whether their statistical model will 'find' social contagion in every outcome they examine because of the limitations," Jason M. Fletcher of Yale University wrote in an e-mail. He and a colleague conducted a similar analysis using data from a large federal survey to show that acne, headaches and even height could appear to be spread through social networks if not analyzed properly.

Christakis and Cacioppo defended their work, saying their statistical methods accounted for other explanations. And others hailed the work.

"I think it's an incredible piece of research," said Mark R. Leary, a professor of psychology and neuroscience at Duke University. "I don't think we anticipated that something like loneliness would cluster like this in a population. It's surprising."

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