TORONTO - Some smokers who suffered damage to a particular area of the brain were able to butt out for good with no effort, researchers have found, suggesting the region could be a target for drugs or other interventions to break the cycle of addiction.
The insula, a region deep within the brain that is a little bigger than a toonie, is believed to translate physical signals from the body into emotional feelings such as anxiety, hunger or a craving, said co-principal investigator Dr. Antoine Bechara of the Brain and Creativity Institute at the University of Southern California.
Bechara, a native of Toronto who has worked in the United States for many years, said he and his research colleagues discovered the insula could be a possible player in addiction after a patient reported quitting tobacco cold turkey after experiencing a stroke.
The 28-year-old man had been smoking since age 14 and was up to 40 cigarettes a day before his stroke, the researcher said, noting that the man had tried unsuccessfully to quit several times before.
"But after he had the stroke -- the last time he had a cigarette was on the evening of his stroke -- when he recovered he never called for another cigarette,'' Bechara explained from Los Angeles. "And people around him, especially his wife, were surprised and amazed that he never asked for a cigarette.''
"He never felt like it. It was as if a switch went off, and to put it in his own words: `It's as if my body forgot I had an urge to smoke.' So it was complete quitting with ease and no effort whatsoever.''
The researchers, whose study is published in Friday's issue of the journal Science, then decided to study other smokers from a registry of brain-damaged patients at the University of Iowa, with which they are affiliated. (Brain damage can be caused by stroke, other neurological diseases or physical head trauma.)
Out of 69 patients, they found 19 with brain lesions that incorporated the insula. Of those, 13 had quit smoking -- and 12 of them had done so immediately and easily. The researchers don't know why the remaining six kept smoking.
Bechara and his colleagues concluded that insula damage reduced the patients' actual urge to smoke. (It did not affect feelings associated with personal or species survival, such as hunger and sex drive, which are also linked to the insula.)
"From a theoretical perspective, I do suspect that the insula also plays a role in the pleasure that you also get from smoking,'' he said. "But from this study we could not get at that directly.''
"So that's why we suggest that probably what we were doing, we were disrupting the urge that drives someone to go and smoke.''
Calling the research "good detective work,'' Toronto addictions expert Dr. Tony George said that while nicotine may be the substance that hooks people by acting on the brain reward pathways, there are likely other pathways "that contribute in an additive or synergistic way.''
"So the nicotine's there to give you the reinforcement and the drug-seeking behaviour, but then there's the non-nicotine aspects, particularly the cues -- the people and places and things that bring on the urges and cravings,'' said George, head of addiction psychiatry at the Centre for Mental Health and Addiction.
"So if what this paper's saying is correct, if you're taking away the urge to do this, it's sort of like taking chocolate out of chocolate cake. It just makes it not very palatable any more,'' he said, suggesting the finding could represent a major advance in understanding drug dependence.
Peter Stern, senior editor of Science, described the study as "quite forward-looking.''
"In addition to investigating a basic scientific mechanism underlying drug addiction, these authors have come up with innovative ideas about how we may be able to treat addiction and prevent relapse,'' he said in a statement.
What doctors can't do, obviously, is drill into the brain and deliberately damage the insula as a way of blocking feelings that help fuel addictive behaviour.
But Bechara said drugs could be designed that would target the area to interfere with signals of nicotine withdrawal being sent from the body, and there may be other techniques that could be developed to have a similar effect.
One of those is transcranial magnetic stimulation -- which involves inducing weak electrical currents in brain tissue that creates a temporary lesion. But as current technology stands, it is able only to reach the outside surface of the brain.
"We would need to advance the technique,'' Bechara said.
Still, the notion of interrupting the insula's message board holds promise -- and not just for those hooked on tobacco.
"The importance of this study is that in all our attempts for finding cures for addiction, probably we've been looking at other areas,'' he said. "This area, the insula, has always been under our nose and this is now an area that is now like a target that we can go after. And if we can find the ways to control some of its functions, we can actually disrupt cycles of addiction.''
"In our particular case, it was smoking addiction, but I see that to be also relevant to addictions to alcohol, addictions to drugs and maybe other addictions.''
