Scientists have identified an area of the brain where damage seems to quickly halt a person’s desire to smoke. The region could form a target for novel therapies to help people quit smoking, the researchers say.
Led by neuroscientist Antoine Bechara of the University of Southern California in Los Angeles, the team homed in on this brain area after learning about an unusual stroke patient whom they identify only as N. From age 14, N. had been a heavy smoker. But after his stroke at age 28, he never lit up again.
Smokers typically undergo well-characterized emotional and physical withdrawal symptoms that make quitting extremely difficult. However, N. effortlessly quit smoking immediately after his stroke and never relapsed. He told doctors, “My body forgot the urge to smoke.”
Bechara says, “What is striking is that it was as if a switch had been turned off—he quit just like that, without any effort at all.”
To see whether brain damage caused by N.’s stroke played a role in his smoking cessation, Bechara and his colleagues scanned N.’s brain to identify the stroke-affected area. They spotted damage in the insula, a region deep inside the cerebral cortex. The insula had previously been associated with monitoring the body’s internal conditions and controlling conscious urges, such as the desire to eat.
The researchers next identified 69 smokers or former smokers with a variety of damaged brain areas caused by strokes, surgery, or other factors. Nineteen of these patients had damaged insulas, and all had quit smoking.
After surveying all the patients, the team found that 18 of the patients with insula damage had quit smoking as uneventfully as N. had. However, most of the 13 other people who had quit smoking had experienced typically tough withdrawal symptoms.
“When we did all our analysis and statistics, it turned out that the likelihood of quitting smoking with ease after insula damage was 136 times higher than for damage anywhere else in the brain,” says Bechara.
He and his team report these results in the Jan. 26 Science.
Neuroscientist Steven Grant of the National Institute on Drug Abuse in Bethesda, Md., calls the researchers’ report “an outstanding paper.”
“To have any kind of variable produce this rate of quitting cigarette smoking is remarkable, to have it associated with a particular brain region is fantastic, and to have it associated with a brain region that we haven’t normally looked at a lot in addiction makes it really high profile,” says Grant.
Researchers would never purposely damage people’s insulas to curb smoking addictions, Grant explains. However, he notes that further information about the insula’s role in addiction could lead to new antismoking therapies.
“This opens up the possibility of novel medications that could be developed to quiet the insula that perhaps might be more effective than the [smoking-cessation drugs] we have now,” he adds.