In a research development that the director of the National Institute on Drug Abuse (NIDA) calls nothing short of “ming-boggling,” stroke victims lost all desire for cigarettes after suffering damage to a tiny structure in the forebrain. The stroke victims who smoked were seemingly freed from nicotine addiction by damage to the insula, a part of the brain that has not previously been a primary target of addiction research.
Along with the nucleus accumbens, the amygdala, and other structures in the limbic system, certain regions of the cerebral cortex are also implicated in active addiction. Now, said NIDA’s Dr. Nora Volkow, “Everybody’s going to be looking at the insula.”
Researchers at the University of Iowa and the University of Southern California collaborated on the brain injury study, published in the January 26 issue of Science. Neuroscientist Antoine Bechara of USC had learned of a stroke patient known only as N.
A heavy smoker from the age of 14, N. quit cold after a stroke at age 28, telling doctors: “My body forgot the urge to smoke.” A striking percentage of smokers with similar damage to the insula had apparently quit smoking after the injury just as effortlessly as had Patient N.
The role of the insula in brain activity is not well understood, but neurologists believe that the structure may help integrate subcortical inputs into coherent emotions and conscious urges.
No one is suggesting brain surgery for nicotine addiction, but researchers hope to discover ways of interfering with the operation of the insula, perhaps by means of a targeted drug. However, it is not yet clear what other functions the insula may perform, and whether the damage that seemingly eliminates the cigarette urge might also eliminate more positive urges and emotions as well.
--Naqvi. N.H., et. al. “Damage to the insula disrupts addiction to cigarette smoking.” Science 315 531-534. Jan 26, 2007.