Study: Loneliness is contagious, spreads like flu

WASHINGTON - Loneliness is contagious and can spread through society like the flu, a new study suggests.

"It's like the edge of a sweater," says Nicholas Christakis, co-author of the Harvard Medical School study. "You start pulling at it and it unravels the network."

The study - which was published in the December edition of the Journal of Personality and Social Psychology suggests maintaining healthy social connections may be as important for public health as hand washing.

The research is based on data from a Framingham, Mass. study that led to a deeper understanding of heart disease by following thousands of people for more than 60 years.

Reconstructing more than 12,000 social ties, Christakis and James Fowler of the University of California, San Diego found:

• Loneliness is easier to catch from friends than from family
• Loneliness spreads more among women than men
• Loneliness is most contagious among neighbors who live close by (within one mile)
• Loneliness can extend to three degrees of separation

One lonely friend increases the risk of loneliness 40 to 65 percent; a lonely friend-of-a-friend adds a 14 to 36 percent risk; a lonely friend-of-a-friend-of-a-friend increases the likelihood of loneliness to a 6 to 26 percent risk.

However, Yale School of Public Health researcher Jason Fletcher isn't so sure. He tells Science News the controls in the study are not solid enough to exclude environmental factors or the tendency of lonely birds-of-a-feather to flock together.

But Fletcher does not deny the existence of socially contagious emotions.

"We're not naysayers," he says.

Fletcher is author of a study showing that headaches, height and acne also spread through networks -- even if their social transmission is unlikely.

Study leader and University of Chicago psychologist John Cacioppo says lonely people become hyper-alert to social threats.

"You engage in more self-protective behavior, which is paradoxically self-defeating," Cacioppo says.

Although lonely people have social connections, those relationships become sterile and unsatisfying, Cacioppo says. The resulting sense of isolation spreads to the friends and neighbors of those who are lonely.

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