The decision to quit smoking appears to be taken up almost communally, with whole clusters of spouses, friends, siblings and co-workers giving up the habit at about the same time, revealed by researchers.
The study is published in the May 22 issue of the New England Journal of Medicine.
The researchers ? Nicholas Christakis of Harvard Medical School and James Fowler of UC San Diego ? analyzed changes in smoking behavior from 1971 to 2003 in a large social network of 12,067 densely interconnected people.
Using data from the Framingham Heart Study (which was the first to identify the link between smoking and cardiovascular disease), the researchers observed that smoking behaviors are subject to similar social-network effects, at two and three degrees of separation. Except that quitting smoking, they found, spread through the network not only like one domino knocking down the next, which in turn knocks down another, but also like a house of cards collapsing.
Generally, the researchers found, the closer the relationship between contacts, the greater the influence when one person quit smoking. When one spouse quit, for example, the other spouse’s chances of continuing to smoke decreased by 67 percent. Among friends, the effect was 36 percent. Among co-workers in small firms, 34 percent. Among siblings, the effect was 25 percent. Neighbors did not seem to be influenced by one another’s smoking habits.
Education played a role: Among friends who both had at least one year of college, the effect was 61 percent. The paper concludes that the educated are not only more influential, but also that they are also more easily influenced.
Network phenomena might be exploited to spread positive health behaviors, and targeting groups, not just individuals, might be more effective.
This research was funded by the U.S. National Institutes of Health/National Institute on Aging, a Pioneer Grant from the Robert Wood Johnson Foundation, and a contract from the National Heart, Lung, and Blood Institute to the Framingham Heart Study.
Source: University of California, San Diego, USA