I’ve written previously about Christakis et al.’s remarkable study that traces the spread of obesity through social networks (i.e., your friends, although generally same gender friends). Christakis et al also believe that smoking is transmitted through social networks (with friends making you more comfortable lighting up or not, depending on what they do).
In Sunday’s New York Times Week in Review, Gina Kolata indicates that Christakis and Fowler are investigating whether depression also travels in social networks (depressed friends make you more depressed or happy friends make you less depressed). There is apparently some evidence on this score from another scholar, Columbia’s Peter Bearman, using the federal National Longitudinal Study of Adolescent Health, “a study of tens of thousands of teenagers that asks them to name their friends and follows them for years. It turned out…that certain friendships increased the likelihood of suicide or suicidal thoughts in teenage girls.
“The risky friendships are what Dr. Bearman calls a contradictory network — a teenage girl has two friends who dislike each other. ‘It tells you about the importance of social relationships for girls’ health and self-esteem,’ Dr. Bearman says. ‘If you are in an unstable triad, it makes it much more difficult to fit in.'”
Bearman and his colleagues are now studying the social spread in the diagnosis of autism. They believe that a large portion of the spread of autism may reflect the increased diagnosis of autism rather than an increase in the disease itself. Bearman believes that if a friend’s child is treated for autism, you are more likely to test your child if he/she shows at all similar behaviors. Then as the concentration of autistic kids spreads in a locality or school, the school becomes sensitized which also further increases diagnosis of autism. So in effect, according to this theory, a social norm of testing and diagnosing for autism spreads through social networks.
As Gail Collins warned, can picking friends based on them being non-smoking, thin, and happy be far behind? And are we soon going to hear criminal defendants citing as their defense that the social norm that killing is OK was spread to them through their friends? And all this work on the negative influence of friends, threatens to overshadow a much longer and more durable scholarly thread (and ultimately more generalizable) in public health about how social support in general is a critical driver of health, happiness, and longevity.
See article text at “You, Your Friends, Your Friends of Friends” (NYT, Week in Review, 8/5/07, Gina Kolata)
See also, Clive Thompson, “Is Happiness Catching?” (NYT Sunday Magazine, 9/13/09)