Duke University Medical Center researchers said,those who are trying to give up smoking may feel tempted to smoke when they see others light up.
Appearing online in Psychopharmacology, the study report says that brain scans taken during normal smoking activity, and 24 hours after quitting, have shown that there is is a marked increase in a particular kind of brain activity when quitters see photographs of people smoking.
Joseph McClernon, an associate professor in the department of psychiatry and behavioral sciences, says that this study casts new light on why it is so hard for people to quit smoking, and why they relapse so quickly.
"Only five percent of unaided quit attempts result in successful abstinence. Most smokers who try to quit return to smoking again. We are trying to understand how that process works in the brain, and this research brings us one step closer," says McClernon.
During the study, the researchers visualized changes in brain activity that occurs when smokers quit, with the aid of a brain-imaging tool called functional MRI.
They scanned the smokers once before quitting, and again 24 hours after they quit.
Each time the participants were scanned, while they were being shown photographs of people smoking.
"Quitting smoking dramatically increased brain activity in response to seeing the smoking cues, which seems to indicate that quitting smoking is actually sensitising the brain to these smoking cues," says McClernon.
He adds that even more surprising is the area of the brain that was activated by the cues.
"We saw activation in the dorsal striatum, an area involved in learning habits or things we do by rote, like riding a bike or brushing our teeth. Our research shows us that when smokers encounter these cues after quitting, it activates the area of the brain responsible for automatic responses. That means quitting smoking may not be a matter of conscious control.
So, if we're really going to help people quit, this emphasizes the need to do more than tell people to resist temptation. We also have to help them break that habitual response," he says.