Friday , January 26, 2007
WASHINGTON —Damage to a silver dollar-sized spot deep in the brain seems to wipe out the urge to smoke, a surprising discovery that may shed important new light on addiction.
The research was inspired by a stroke survivor who claimed he simply forgot his two-pack-a-day addiction — no cravings, no nicotine patches, not even a conscious desire to quit.
"The quitting is like a light switch that went off," said Dr. Antoine Bechara of the University of Southern California, who scanned the brains of 69 smokers and ex-smokers to pinpoint the region involved. "This is very striking."
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The finding, reported in Friday's edition of the journal Science, points scientists toward new ways to develop anti-smoking aids by targeting this little-known brain region called the insula. And it sparked excitement among addiction specialists who expect the insula to play a key role in other addictions, too.
"It's a fantastic paper; it's a fantastic finding," said Dr. Nora Volkow, director of the National Institute on Drug Abuse and a longtime investigator of the brain's addiction pathways.
"What this study shows unequivocally is the insula is a key structure in the brain for perceiving the urges to take the drug," urges that are "the backbone of the addiction," Volkow added.
Why? The insula appears to be where the brain turns physical reactions into feelings, such as feeling anxious when your heart speeds up. There are nicotine receptors in the insula, meaning it should be possible to create a nicotine-specific drug, Bechara said — albeit years from now.
More immediately, NIDA's Volkow wants to try a different experiment: Scientists can temporarily alter function of certain brain regions with pulses of magnetic energy, called "transcranial magnetic stimulation." She wants to see if it is possible to focus such magnetic pulses on the insula, and thus verify its role.
Other neurologic functions are known to be involved with addiction, too, such as the brain's "reward" or pleasure pathways. The insula discovery does not contradict that work, but adds another layer to how addiction grips the brain, Bechara said.