Brain injury helps some smokers quit

Smokers with injuries in a specific part of their brains kick their habits instantly – without the intense cravings that can make it so hard to quit, a new study reports.

Researchers from the University of Southern California and the University of Iowa linked a brain area called the insula to the powerful urges that cause people to continue smoking.

Smokers with damaged insulas were more than 100 times more likely to have their addictions erased than smokers with damage in other parts of their brains, researchers said.

One man who smoked an average of 40 cigarettes a day before a stroke damaged his insula was surprised to suddenly lose all cravings for tobacco. He told researchers his body “forgot the urge to smoke.”

“It was like a switch was turned off,” explained Antoine Bechara, a neuroscientist at USC and senior author of the paper.

The research, published today in the journal Science, opens a new front in addiction research and may lead to improved treatments for smokers, experts said.

Although intentionally damaging the insula would be too risky, it might be possible to develop drugs or medical devices that could temporarily disable the region’s circuitry, relieving smokers of the urge long enough to quit, scientists said.

However, Dr. Jed Rose, director of the Center for Nicotine and Smoking Cessation Research at Duke University, cautioned against drawing broad conclusions from the research. Rose said no more than 5 percent of smokers are able to permanently quit on their own.

Most smoking research has focused on the cortex, the brain region involved in reasoning and decision-making. Nicotine in tobacco spurs the release of brain chemicals in the cortex that generate pleasurable feelings. Smoking addiction has been largely understood as a drive to feel pleasure, said Henry Lester, a neurobiologist at California Institute of Technology.

Smoking-cessation drugs target the brain’s pleasure circuitry, but are not very effective in helping smokers quit long-term, Rose said.

The researchers examined 32 former smokers who had suffered some form of brain damage. The patients were asked how hard it was for them to stop smoking and whether they felt urges to smoke after they quit.

Sixteen of the patients said they quit effortlessly after their brain injuries.

The scientists used brain-imaging equipment to identify the damaged areas of patients’ brains. Of the 16 patients who found it easy to quit smoking, 12 had damaged insulas. The remaining patients showed injuries in other parts of their brains.

Bechara said that in patients with damaged insulas, other brain circuits involved in addiction remained intact. The result shows “if we can knock out this one area, we can disrupt the whole cycle of addiction,” he said.

The insula, about the size of an apricot, is believed to integrate emotions with information about certain bodily functions, such as pulse rate or breathing. The information is processed instantaneously. For example, a smoker might become calm when a puff of smoke enters the lungs.

Lester said the insula helps explain why so many smokers liken their addiction to bodily needs, such as thirst.