WASHINGTON - Just seeing someone smoke aborts the smoker’s resolve to kick the habit, according to new research.

Brain scans taken during normal smoking activity and 24 hours after quitting show there is a marked increase in a particular kind of brain activity when quitters see photographs of people smoking.

The study sheds important light on why it’s so hard for people to quit smoking, and why they relapse so quickly, explains Joseph McClernon, associate professor of psychiatry and behavioural sciences at Duke University Medical Centre (DUMC).

‘Only five percent of unaided quit attempts result in successful abstinence,’ said McClernon. ‘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.’

The Duke researchers used a brain-imaging tool called functional MRI to visualise changes in brain activity that occurs when smokers quit. The smokers were scanned once before quitting and again 24 hours after they quit. Each time they were scanned while being shown photographs of people smoking, said a DUMC release.

‘Quitting smoking dramatically increased brain activity in response to seeing the smoking cues,’ said McClernon, ‘which seems to indicate that quitting smoking is actually sensitising the brain to these smoking cues.’

Even more surprising, he adds, 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,’ he added.

‘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,’ said McClernon.

The study appears online in Psychopharmacology.