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Stroke Reveals the Smoking Gun behind Nicotine addiction

Sun, 28th Jan 2007

Part of the show Extreme Organisms and Hydrothermal Vents

Scientists in the US have identified a coin-sized region of the brain responsible for nicotine addiction. Writing in this week's edition of Science, University of Iowa researcher Nasir Naqvi and his colleagues studied quit-rates amongst 69 smokers who had suffered strokes. 19 of the subjects had damage to a part of the brain called the insula cortex, and these individuals were much more likely to stop smoking in the wake of their strokes, often without difficulty, compared with subjects who had strokes affecting other parts of the brain. The effect was also more marked when it involved the insula in the right side of the brain compared with the left, but the study was too small to confirm the significance of this. So why this marked effect? Well, argue the researchers, the insula, which sits between the brain's temporal and frontal lobes, is thought to play a role in anticipating the bodily effects of emotional events. In other words it might help addicts to anticipate the pleasure of having a cigarette, and the relief from unpleasant withdrawal symptoms. In this respect it might help to motivate smokers to light up because it creates the feeling that smoking is a bodily need. But when this area of the brain is damaged it's as if, in the words of one patient, "the body has 'forgotten' the urge to smoke." The team hope that the identification of this link between the insula and smoking addiction will help scientists to better understand, with the help of brain scans and behavioural studies, the neurological basis of addiction, and develop better ways to help smokers to give up for good.

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