Studies Find Smoking Cessation Medications Promising
A new study has found that the smoking cessation medications bupropion and varenicline may be associated with changing the way the brain reacts to smoking cues, helping people resist nicotine cravings. Two reports with the same conclusion will be published in the May 2011 print issue of Archives of General Psychiatry.
The researchers note that environmental cues that trigger nicotine cravings often lead to relapse in people who are trying to quit smoking. Previous studies using functional magnetic resonance imaging (fMRI) and positron emission tomography scanning have shown that some brain regions are associated with cue-induced cigarette cravings. When looking at cigarette-related cues, those who are dependent on nicotine showed increased brain activity related to attention, emotion, reward, and motivation.
Previous studies have found that bupropion, which was originally an anti-depressant, increased the smoking cessation rates of smokers who also suffered from depression. It has also been shown to reduce cravings that are triggered by environmental cues, but the mechanisms of this are not well understood.
For one study, Christopher S. Culbertson, Ph.D., of the University of California, Los Angeles, and colleagues looked at the changes in brain response to smoking cues through brain scans of 30 smokers who randomly received bupropion or a placebo for eight weeks. Brain scans were completed after the first and eighth weeks of the study. During the scan, participants were shown 45-second videos that either featured smoking cues (actors and actresses smoking in different settings) or environmental cues (similar settings but no smoking). The participants also reported how strongly they craved cigarettes using a response box immediately after watching each video.
The researchers found that those who were given bupropion reported fewer cravings in response to the smoking cues than those who were given a placebo. Those who took bupropion also showed reduced brain activity in the areas associated with cravings.
Among all patients, those who showed reduced activation in areas of the brain that were associated with cravings reported fewer cigarette cravings. The authors conclude that the results suggest that bupropion could help people resist cravings that are triggered by environmental cues and reduce the brain activation of craving-associated areas.
In a second study, Teresa Franklin, Ph.D., of University of Pennsylvania, Philadelphia, and colleagues studied the medication varenicline, which reduces the withdrawal symptoms and the rewarding effects of nicotine. The researchers examined whether the medication would also reduce brain responses and cravings when smokers were exposed to smoking cues using fMRI brain scans.
In this study, 22 smokers were given either varenicline or a placebo over three weeks, and brain scans were taken before and after the treatment period, both while “at rest” and while viewing 10-minute videos that featured either smoking cues or non-smoking cues. The participants also reported their craving levels. The participants continued smoking during the study period so that researchers could fully examine the medication’s effects on the response to cravings without dealing with withdrawal symptoms, as they affect brain activity.
In the “before” scans, smoking cues activated brain regions associated with drug-seeking behavior, and the participants reported smoking cravings. In the “after” scans, those who were given varenicline had reduced brain activity in the brain regions and in reported cravings, while similar patterns persisted in those who were given a placebo.
In the “at rest” scans of those who took varenicline, brain activity was increased in a region of the brain that is associated with inhibiting behavior that predicts reward, such as smoking cues. This suggests that the medication helps reduce smoking cravings.
The authors said that because unsuccessful attempts to quit smoking is more common in people with psychiatric illnesses, varenicline and other medications may be very effective in helping people quit smoking, especially those who have a harder time quitting. They concluded that these medications can reduce both withdrawal symptoms and smoking cravings, especially in those who are more susceptible to relapse and smoking cues.
Source: Science Daily, Brain Imaging Studies Examine How Anti-Smoking Medications May Curb Cravings, January 3, 2011
