Experts have suggested that two drugs that help smokers kick the butt - bupropion and varenicline - may be associated with changes in the way the brain reacts to smoking cues, making it easier for patients to resist cravings.
“Environmental cues associated with nicotine reinforcement induce cigarette craving, which propagates smoking habits in smokers and relapse in abstinent individuals,” the authors wrote in one of the articles.
Bupropion, originally marketed as an antidepressant, is prescribed around the world to help people resist smoking cues. But the mechanism for doing so has not been clear.
In one study, Christopher S. Culbertson of the University of California, Los Angeles and his team measured the changes in the brain activity of 30 smokers who were randomly told to take either bupropion or a placebo for a period of eight weeks.
Within a week of joining the study and again after it ended, the participants underwent brain scans. During both the scans, they were shown 45-second videos of actors smoking in various settings as well as clips in which no one was smoking. They were asked to press buttons on a box indicating how strongly they craved cigarettes immediately after watching each video.
The smokers who took bupriopion said they craved cigarettes less even while watching others smoking than those who took the placebo. Those on the drug also showed a decrease in the activation of areas of the brain responsible for cravings. “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 researchers concluded.
In a second study, Teresa Franklin of the University of Pennsylvania and her team looked at how the brain reacted to varenicline, which reduces the symptoms of withdrawal and reinforcement smokers get from nicotine.
The participants also watched 10-minute videos, with either non-smoking or smoking cues, and had to report on the levels of their cravings. The findings were similar to those of the other study. Smoking cues activated regions of the brain linked to drug motivation and triggered craving feelings. But those who took the drug reported reduced cravings and showed a reduction in brain activity in those areas, said the researchers. “The results of our study reveal a distinctive new action that likely contributes to its clinical efficacy,” they concluded.
“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 who may also be more vulnerable to relapse in the presence of smoking cues,” they said.
Both the studies are published online in the Archives of General Psychiatry.