The NY Times had an interesting article about a longitudinal study of cigarette smoking and social networks. Nicholas Christakis (Harvard Medical School) and James Fowler (UCSD) looked at the social networks of thousands of smokers and non-smokers over a 32-year period, from 1971-2003, when the number of smokers in the US declined by more than half. The authors found that clusters of smokers "quit en masse" as years went by. Not only that, other social clusters associated with quitting clusters also tended to stop smoking.
Dr. Christakis described watching the vanishing clusters as like lying on your back in a field, looking up at stars that were burning out. “It’s not like one little star turning off at a time,” he said. “Whole constellations are blinking off at once.”
It isn't terribly surprising that social factors are involved in quitting. Individuals within social groups tend to be demographically similar, so I would expect that, within clusters, similarities in shifting values and preferred activities would exert effects along with evolving mutual pressures and influences on behavior.
The author of the study also noted that smokers become increasingly isolated as social clusters became non-smoking clusters.
As cluster after cluster of smokers disappeared, those that remained were pushed to the margins of society, isolated, with fewer friends, fewer social connections. “Smokers used to be the center of the party,” Dr. Fowler said, “but now they’ve become wallflowers... We’ve known smoking was bad for your physical health,” he said. “But this shows it also is bad for your social health... Smokers, he said, “are likely to drive friends away.”
That last claim makes for a nice anti-smoking message — if you smoke, you'll end up lonely — but I'm less than confident that this assertion entirely explains the relationship between social isolation and smoking. The link is probably more complicated and less direct, involving multi-directional relationships between a number of factors.
In an editorial set to accompany the publication of the article in the New England Journal of Medicine, Steven Schroeder (UCSF) warns that “marginalization… of smoking… further isolates the group of people with the highest rate of smoking — persons with mental illness, problems with substance abuse, or both.”
This is true, but psychopathology itself, apart from smoking, may account for growing social isolation. Yes, social isolation, in turn, may leave individuals less subject to the prevailing social influences of non-smokers. But psychopathology is, itself, associated with smoking as a form of self-medication. On the physiological level, nicotine has both antidepressant and anxiolytic effects.
Use of some psychotropic medications is also associated with higher rates of smoking. Nicotine attenuates the side effects of antidopaminergic medications typically used in the treatment of more severe psychopathology. Individuals on these medications tend to smoke more and, independent of their smoking, tend to be more socially isolated. So, I do wonder if social isolation is less a consequence of smoking than an effect of multiple factors associated with higher rates of nicotine use.