Summary

A new report from the Framingham Heart Study suggests that social behavior is an important factor in whether people smoke or not. Smokers are likely to cluster together and when one quits, others close to them are more likely to give up. These findings could inform public health efforts on smoking cessation.

Introduction

Smoking remains the leading preventable cause of death in the United States. In 2004, there were still around 45 million smokers, although rates of smoking have gone down from 45 percent to 21 percent over the last 40 years. To help those remaining smokers quit, it's important to understand more about smoking behavior to find out how to make cessation easier and more successful.

Social networks are known to be an important factor in both the initiation and cessation of smoking. Previous work on this has concentrated on young people however. Researchers for the famous and long-running Framingham Heart Study - which has taught us most of what we know about heart disease risk factors - decided to go for a more comprehensive approach.

What was done

The Framingham researchers evaluated a network of 12,067 people over 32 years. They assessed their smoking behavior periodically and recorded their social network ties with one another. They looked for 'clusters' of smokers and non-smokers in the networks, the association between one person's smoking behavior and that of their social contacts and how this relationship depends on the nature of the tie (family, friend or co-worker). They also found out about the influence of education, whether smoking cessation occurs in large sub-groups, and how smokers tend to move to the margins of a social network over time.

What was found

In 1971 there were many more smokers than in 2000 and at the earlier time, smokers occupied a center position with their families and friends. By 2000, those who still smoked were no longer at the center, socially. They had moved to the margins and associated mainly with other smokers. Distinct social clusters of smokers and non-smokers emerged.

When it came to smoking cessation, it seemed to spread from person-to-person. If a spouse stopped, then the partner's chance of continuing to smoke went down by 67 percent. Smoking cessation by a brother or sister decreased the risk of someone continuing to smoke by 25 percent. The chances of continuing decreased by 36 percent if a friend quit and by 34 percent for a co-worker in a small company. Therefore, cessation behavior seems to be catching. Friends with a higher level of education tended to be more influential on those with a similar level of education.

What this study means

Smoking is not an isolated behavior. People are influenced by others close to them who smoke or who do not. These behaviors are likely to be intensified by legislation in many countries which bans smoking in public places. This means that public health effects should try to exploit the influence of peer behavior more - maybe by looking at group, rather than individual, interventions. It also means that current smoking cessation campaigns might be more successful than previously supposed - one person quits, but inspires others close to them to do likewise. And, finally, the finding that smokers socialize in clusters might encourage policy makers to target these groups for smoking cessation rather than aim at the whole population.