According to a new study, if a person's spouse quits smoking he/she is 67% less likely to smoke, and friends of a person who quits are 36% less likely to smoke, while siblings are 25% less likely. Even though smoking is addictive, giving up seems to be catching.
In this study, published in The New England Journal of Medicine, Nicholas Christakis from Harvard Medical School and James Fowler from the University of California in San Diego, assessed people's smoking habits and studied what effect giving up had on the probability of wives, siblings, friends, and work colleagues continuing to smoke. The study appears to show that quitting does have a major impact on other people's smoking habits, what the researchers call "the collective dynamic of smoking behaviour".
When the Framingham Heat Study started in 1948 there were 5209 participants. 5124 people were added to the study in 1971 - the additions consisted of the original group's children and spouses. A further 508 were added in 1994, plus 4095 offspring in 2002.
The present study focused on 5124 people, consisting mainly of the children of the previous groups. The researchers were able to find 53,000 family ties with other people in the network - approximately 10.4 family ties per person.
clusters of smokers and non-smokers appear to develop - smokers are more likely to be linked to other smokers, while non-smokers do so with other non-smokers. This clustering extends to three degrees of separation. Even though the percentage of smokers dropped, smoking clusters remained pretty constant throughout the whole period of the study - this suggest that whole groups of people were quitting at the same time.
If a husband stops smoking the chances of his wife smoking drops by 67% and having a brother or a sister who stops smoking will reduce the chances of his or her sibling smoking by 25%. The authors think that this knock on effect of stopping people smoking has been a major factor in the decline in smoking seen in Western countries over the past few decades.
