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Scientists find brain’s cigarette addiction centre

by Ed Yong | Analysis

13 July 2007

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The insula controls a smoker's addiction to cigarettesBy this point of the year, most of my New Year’s resolutions have gone out the window and I’m sure many of you feel the same.

For lots of people, the urge to indulge in bad habits remains frustratingly strong.

These urges are particularly important when it comes to smoking. Smoking is the single biggest cause of cancer in the world. Surveys have repeatedly shown that most smokers want to quit, but find it very difficult.

Now, scientists from the University of Iowa have found that a small part of the brain called the insula controls a smoker’s addiction to cigarettes. People who suffer brain damage in their insula as the result of a stroke, completely lose their urge to smoke.

While most smokers take a long time and many attempts to quit, those with damaged insulas quit easily and immediately. They never touched a cigarette again, and never even felt the urge to do so.

One man, who suffered damage to his insula following a stroke, said that his body just ‘forgot the urge to smoke’.

The insula processes information from the rest of the body and uses it to produce emotional experiences, such as craving or hunger. For example, in people addicted to smoking, it could take in the sight of a cigarette, the smell of smoke and the memory of a nicotine hit and produce a conscious urge to smoke.

The idea is that becoming addicted to nicotine changes the insula so that smoking becomes just as necessary a bodily need as hunger or thirst. And damage to the insula reverses this effect.

Of course, the big question that this research poses is: “Can this knowledge be used to help smokers to quit?”

Directly affecting the insula, either through surgery or electrical stimulation, seems a drastic step. The major worry would be that it would have knock-on effects on other aspects of a person’s life.

So a surgical cure for smoking still seems like a distant possibility. But identifying the insula as the brain’s smoking addiction centre could help in other ways.

Monitoring brain activity in the insula could assist scientists – such as Cancer Research UK’s Health Behaviour Unit at UCL, London – in comparing the effectiveness of different methods for quitting smoking. Or scientists could develop drugs that specifically target chemicals that are used in the insula.

In the mean time, it is worth remembering that giving up smoking can be difficult, but so far, over eleven million people in the UK have successfully done it.