Amazingly Breaking Addiction
Brain-damaged smokers provide clues to anatomy of addiction

25^th January 2007

CHICAGO (AFP) - Smokers who suffered damage to one of the brain's pleasure centers were able to kick the habit effortlessly, according to a study which may point to new treatments for people seeking to beat nicotine addiction.

The study found that many smokers who suffered damage to a brain structure called the insula lost their desire for a cigarette virtually overnight, suggesting that this region of the brain may be critical to the physiology of addiction.

Written by researchers at the University of Southern California (USC) and the University of Iowa, the study was inspired in large part by the case of a 38-year-old man who underwent a stunning transformation after suffering a stroke. A hard-core smoker who had been lighting up since the age of 14, the man was puffing his way through 40 unfiltered cigarettes a day until his attack.

Then, literally overnight, he lost the yen and even began to feel disgusted by the smell of stale tobacco. In fact, such was his newfound revulsion to his old habit that he asked to change hospital rooms because he could not bear the odor of cigarettes on his roommate after the man came back from an outdoor cigarette break.

Asked about his sudden change of heart, the 38-year-old told researchers: "My body forgot the urge to smoke." He vowed that the shift had nothing to do with his health crisis, even though he suspected his stroke was brought on by his two-pack-a-day habit.

Intrigued, researchers turned to a register of brain-damaged patients to see whether his case was unique, or whether his type of brain damage somehow stifled the urge to light up.

They looked at 69 brain-damaged patients, 19 of whom had sustained damage to a deep-brain region called the insula -- the same structure that was impaired in the stroke victim.

Of the 19, thirteen had quit smoking, and 12 of those said they had quit instantaneously and were not troubled by any lingering cravings. Some of the other patients had also kicked their habits, but overall, the ones who had quit easily were more likely to have suffered damage to the insula, according to the study, which appears in the journal Science.

"It's really intriguing to think that disrupting this region breaks the pleasure feelings associated with smoking," said study author Hanna Damasio, director of the Brain and Creativity Institute at USC.

"It's immediate. It's not that they smoke less. They don't smoke, period," Damasio said.

The finding that one small region could be the Achilles' heel of smoking addiction is surprising, given the brain-wide effects of nicotine on the nervous system, the researchers said.

The region has not drawn much attention from investigators working in the field of drug addiction, but that will probably change now.

"One of the most difficult problems in any form of addiction is the difficulty in stopping the urge to smoke, to take a drug or to eat, for that matter. Now we have identified a brain target for further research into dealing with that urge," said Antoine Bechara of USC, a senior author on the study.