A recent post in the San Francisco Chronicle suggests that there may be a link between smoking addiction and a part of the brain called the insular cortex.
"In the latest study, published in this week's issue of the journal Science, researchers at the University of Southern California and University of Iowa found that longtime smokers who had sustained insula damage had a remarkably easy time giving up cigarettes."These researchers examined 19 patients who were smokers and had damage to their insular cortex. These patients were compared to 50 other smokers who had brain damage in other areas of the brain.
They found that 13 of the 19 insula-damaged patients quit smoking and from those only 1 had a difficult time quitting. The article did not report the 'quit-smoking' stats for the control group, instead it just read that the other group of brain-damaged smokers had a significantly less number who quit.