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A particular region of the brain may drive smoking addiction, say scientists who found stroke survivors with damage to their insular cortex more easily kicked the habit.

They studied 156 stroke patients with different patterns of brain injury.

More of those with insular cortex damage successfully gave up smoking and reported fewer withdrawal symptoms than the other stroke patients.

Experts say targeting this brain area may help other smokers quit.

Most stop smoking medicines currently on the market work by blocking the brain's reward pathways in response to nicotine.

And patches and gums aim to lessen cravings by supplying a controlled dose of nicotine as the person weans themselves off tobacco.

But post-graduate researcher Amir Abdolahi and colleagues believe the insular cortex could be a valuable new target for quit smoking aids.

Image copyright JANE SHEMILT/SCIENCE PHOTO LIBRARY

Therapies that could hone in on this area of the brain and disrupt its role in addiction, potentially with new drugs or other techniques such as deep brain stimulation or transcranial magnetic stimulation, should be explored, they say.

"Much more research is needed in order for us to more fully understand the underlying mechanism and specific role of the insular cortex, but it is clear that something is going on in this part of the brain that is influencing addiction," Dr Abdolahi said.

The research findings are published in two medical journals - Addiction and Addictive Behaviors.

Cracking addiction

The patients in the study were smokers who had been admitted to hospital because of a stroke.

Medical scans revealed that 38 of them had suffered damage to the insular cortex, while the remaining 118 had damage to other parts of the brain.

All of the patients were encouraged by their doctor to quit smoking.

The researchers followed the patients for three months to see how many actually quit, and how easy they had found it. A few dropped out of the study.

Of those remaining, almost twice as many patients with strokes in the insular cortex successfully abstained from smoking for three months (22 out of 32 patients, or 70%) compared with those with strokes in other parts of the brain (38 out of 103 patients, or 37%).

And they suffered less from withdrawal symptoms such as cravings, hunger, rage, sleeplessness and anxiety.

The findings support those of earlier work by Dr Antoine Bechara, from the University of Southern California, who reported that stroke patients with damage to the insular cortex had said their body had "forgotten the urge to smoke".

The insular cortex lies deep in the brain and has widespread connections to surrounding regions.

Experts believe its primary role is to do with desires and emotions.