Brain changes spurred by the medications seem to help cut cravings.
Two drugs that help people stop smoking - bupropion and varenicline - may change the way the brain reacts to seeing someone else smoke, new studies report. And that may be how they cut cravings.
Bupropion (Wellbutrin, Zyban) is prescribed around the world to help people resist smoking cues. But it has not been clear how the drug does this. Using brain scans, Christopher S. Culbertson, of the University of California, Los Angeles, and his colleagues examined what happened in the brains of 30 smokers who took the drug or a placebo for eight weeks.
The researchers gauged how much the participants craved cigarettes by asking them to respond after watching "neutral" cues that did not involve smoking or 45-second videos of actors and actresses smoking.
Those who took the drug instead of the placebo reported less craving. They also showed less activity in areas of the brain linked to craving.
"These results demonstrate that treatment with bupropion is associated with an improved ability to resist cue-induced craving and a reduction in cue-induced activation of limbic and prefrontal brain regions," the study authors wrote.
In a second study, Teresa Franklin of the University of Pennsylvania and her colleagues used brain scans to study how the brains of 22 smokers reacted when they took the drug varenicline (Chantix) or a placebo for three weeks. The participants watched 10-minute videos, some of which included smoking cues.
Those who took the drug had less brain activity in some areas and reported less craving after they saw the videos designed to provide smoking cues.
"The results of our study reveal a distinctive new action of varenicline that may contribute to its clinical efficacy," the researchers wrote. "Unsuccessful smoking cessation is more prevalent in individuals with psychiatric illness, suggesting that they have greater difficulty quitting. Varenicline and other medications that can reduce both withdrawal and cue reactivity may be of special benefit to these subgroups." (HealthDay News/ January 2011)