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Brain injury tied to halt in smoking
Research on neural circuitry offers hope of powerful treatment to break nicotine's grip
By Michael Stroh
Tribune Newspapers: The Baltimore Sun
Published January 26, 2007
In a finding that could lead to powerful new treatments for smokers unable to quit, scientists have discovered that people who experienced stroke damage to a prune-sized spot deep within the brain suddenly lost the urge to light up.
The research, published Friday in the journal Science, appears to underscore nicotine's far-reaching grip on a smoker's neural circuitry--and how much there remains to learn about it. Until now, addiction researchers have largely ignored the brain structure implicated in the study--a region called the insula
"It's a really tremendous paper, one that points us in a whole new direction," says Steven Grant, who serves as chief of the clinical neuroscience branch of the government's National Institute on Drug Abuse. He was not involved in the study. "It says: This is a brain area the addiction field needs to focus a lot of attention on."
While intentionally inflicting damage on a smoker's brain is ethically out of the question, scientists said it may be possible to mimic the effect of insula injury with drugs or other therapies. Such treatments also may help people addicted to chemicals other than nicotine, researchers said.
In the study, researchers at the University of Southern California and the University of Iowa looked at 69 smokers with various brain injuries, mostly the result of stroke. All the participants had smoked at least five cigarettes a day for two years or more.
Of 19 smokers whose insula had suffered damage, 13 almost immediately stopped smoking, researchers found. One of the most striking turnarounds involved a mathematician identified as "Patient N."
A smoker since the age of 14, the 38-year-old man typically inhaled more than 40 unfiltered cigarettes a day--his final one on the evening before his stroke.
But when he woke up in the hospital, his cravings were gone. "My body forgot the urge to smoke," he told researchers.
"His quitting was completely effortless, like a switch going off," says Antoine Bechara, a researcher in USC's Brain and Creativity Institute and senior author of the report.
Patient N even became so disgusted by the smell of his hospital roommate, who frequently left the building to smoke, that he asked to change rooms.
Researchers were at a loss to explain what's going on in the brains of Patient N and the others. Another mystery: why six of the insula-damaged subjects did not quit smoking.
Part of the difficulty is that little is known about the insula, although scientists say it's one of the brain's most ancient structures.
As best they can determine, the region plays a role in basic survival, translating signals from various parts in the body into visceral sensations, including hunger pangs and pain.
This study, researchers said, is the first to probe nicotine addiction through the prism of brain damage. But the results fit with what scientists have learned from brain imaging and autopsy research in recent years.
Jack Henningfield, a professor of behavioral biology at the Johns Hopkins School of Medicine, says chronic tobacco exposure leads to changes in the "structure and function" of the brain. "In other words, quitting is not just will power against the desire to smoke. Quitting smoking is a battle with the biology of the brain," he says.
This, he says, helps explain why, of the more than 44.5 million smokers in the U.S., fewer than 5 percent succeed in quitting long term.
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About the insula
The insula, for years a wallflower of brain anatomy, has emerged as a region of interest based in part on recent work by Dr. Antonio Damasio, a neurologist and director of USC's Brain and Creativity Institute. The insula has widely distributed connections, both in the thinking cortex above and down below in subcortical areas, like the brain stem, that maintain heart rate, blood pressure and body temperature, the body's primal survival systems.
-- New York Times News Service
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