|
|
|
2007-9-3 17:37:07 |
|
A brain-damaging stroke in certain area in the brain could help smokers quit smoking immediately, according to a study published Friday in the Jan. 26 issue of the journal Science. The study shows that to cause loss of the craving for nicotine, the stroke may better occur in a 2.5-centermeter wide insula, a small island in the cerebral cortex deep in the brain that has been known to function as a platform for feelings and emotion including nicotine addition. The finding does not suggest a stroke may be induced to help smokers quit smoking. Rather, the finding provides a new target for the drug companies to develop new drugs to disable the function associated with nicotine addition. In addition, the discovery indicates a possibility that neural circuits for pleasure in the insula may also have something to do with other addictive behaviors, meaning that targeting at the insula, a drug may also knock out addictions other than smoking. The study led by Antoine Bechara, of the University of Southern California, Los Angeles and colleagues was triggered by an observation that a smoker whose brain was damaged after a stroke ended up quitting smoking effortlessly and quickly. The 38-year old man who had smoked 40 cigarettes a day told the researchers that his body "forgot the urge to smoke" after he recovered from the stroke in hospital. The man started smoking at age 14 and stopped smoking the night before the stroke. This observation prompted the researchers to investigate 69 smokers with brain-damage, mostly resulting from stroke. All the subjects had smoked at least five cigarettes a day for two years or longer. They found 19 were injured in the insula. Of these 19 people, 13 reported they quit smoking, all but one without any difficulty. "It's really intriguing to think that disrupting this region breaks the pleasure feelings associated with smoking," said Hanna Damasio, co-author of the study, director of the institute and holder of the David Dornsife Chair in Neuroscience at USC. "It is immediate. It's not that they smoke less. They don't smoke, period." Damage in areas other than the insula may also disrupt the craving for nicotine, but was many times less likely than the damage on the insula, according to the researchers. The researchers do not know why the remaining six people failed to quit smoking. The insula has not been researched for its functions associated with addiction until the current study. Further research is needed to learn more about the insula. The insula was a platform for feelings like hunger, pain and cravings and emotions, Dr. Damasio suggested in 1990s. Because other functions are likely involved, any antismoking treatment that is targeted at the particular region in the brain would need to preserve the beneficial functions of the insula, the researchers cautioned. But Dr. Bechara suggested that it might be impossible to target one behavior without disrupting the other as the region appears to be involved specifically in "learned behaviors" rather than the fundamental drives necessary for survival. Dr. Damasio also stressed the difference between habitual and instinctive behaviors. "The fact that insular damage breaks down a learned habit such as smoking, demonstrates a powerful link between habit and emotion or feeling," she said. The study was funded by the National Institute on Drug Abuse and the National Institute of Neurological Disorders and Stroke. Background information about the insula cited from Wikipedia, the free encyclopedia The insular cortex (also often referred to as just the insula) is a structure of the human brain. It lies deep to the brain's lateral surface, within the lateral sulcus which separates the temporal lobe and inferior parietal cortex. These overlying cortical areas are known as opercula (meaning "lids"), and parts of the frontal, temporal and parietal lobes form opercula over the insula. The Latin name for the insular cortex is lobus insularis. The insular cortex is also known by the name Island of Reil, named after Johann Christian Reil. The insular cortex is considered a separate lobe of the telencephalon by some authorities. It is also sometimes grouped with limbic structures deep in the brain into a limbic lobe. |
