Friday, January 26, 2007

Many heavy smokers quit immediately and permanently when a small structure deep in the brain is damaged, a finding that provides a new lead in the search for smoking-cessation treatments, a study says.

“Nicotine addiction depends on a healthy insula” — a region of the brain linked to emotion — say the study’s authors at the Brain and Creativity Institute at the University of Southern California and collaborators at the University of Iowa.

“There is a new target in sight. … It is always amazing to identify targets,” said Antoine Bechara, associate professor of neurosciences and psychology at USC and a senior author of the study. “There is a lot of potential for pharmacological developments.”

Mr. Bechara said the results published today in the journal Science “give hope” that some people who are heavy smokers “will be able to quit without any effort.”

Dr. Hanna Damasio, director of USC’s Brain and Creativity Institute and another senior author of the study, said the research showed that most smokers with insulas impaired by strokes “immediately” kicked the habit.

“It was not that they smoked less; they did not smoke period,” she said.

The insula, the size of a silver dollar and shaped like a football, is enclosed by the cerebral cortex. In the 1990s, Dr. Antonio Damasio, Hanna Damasio’s husband, proposed that the insula is a “platform for feeling and emotion.”

The insula research was sparked by the case of a 38-year-old man who started smoking when he was 14 and had a two-pack-a-day habit. He abruptly quit after suffering a stroke.

The man said he lost his urge to smoke “virtually overnight” and hated being around the smell of stale tobacco. As he recovered from his stroke in a hospital, the man asked for a room change to get away from another patient who smoked.

Researchers looked at the cases of other smokers who had suffered brain damage to see if they could find similar instances.

Of the 69 brain-damaged patients studied, 19 had affected insulas. Of those 19, 13 said they had stopped smoking. Twelve of the 13 said they quit instantly and had no lingering urges.

“The insula is almost always implicated and activated in drug abuse, but it has not been paid attention to” by those involved in such research, Mr. Bechara said.

He suggests that the insula could also play a role in other addictions, such as alcohol and overeating. But he says that is still unknown.

Mr. Bechara stressed that scientists “will have to be careful” in devising medical strategies for the insula that would eliminate its role in nicotine addiction while preserving its beneficial functions.

In addition to potential drug treatments, Mr. Bechara says he hopes a technology known as transcranial magnetic stimulation can also be adapted to help smokers quit.

He said TMS involves sending a magnetic current into one side of the skull, “which causes a temporary lesion.”

But, at this time, “that temporary lesion only reaches the very outside of the brain, not deep inside the brain,” where the insula is located, he said.

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