Marijuana use and tobacco smoking cessation among heavy alcohol drinkers.

BACKGROUND Whereas problem drinking impedes smoking cessation, less is known whether marijuana use affects smoking cessation outcomes and whether smoking cessation treatment leads to changes in marijuana smoking. METHODS In a randomized clinical trial that recruited 236 heavy drinkers seeking smoking cessation treatment, we examined whether current marijuana smokers (n=57) differed from the rest of the sample in tobacco smoking and alcohol use outcomes and whether the patterns of marijuana use changed during treatment. RESULTS Half of the marijuana users reported smoking marijuana at least weekly (an average of 42% of possible smoking days), the other half used infrequently, an average of 5% of possible days. There were no significant differences between the marijuana use groups and non-users on smoking outcomes and marijuana use did not predict smoking lapses. All participants made large reductions in weekly alcohol consumption during the trial, with weekly marijuana users reducing their drinking by 47% and at a faster rate than non-marijuana users after the 8-week follow-up. Weekly marijuana smokers also steadily decreased their marijuana use over the course of the study (at 8-, 16-, and 26-week follow-ups) by more than 24%. CONCLUSIONS These data suggest that frequent marijuana smokers may benefit from smoking cessation interventions, even when marijuana use is not explicitly discussed. These individuals do not show any more difficulty than other cigarette smokers in making efforts to reduce tobacco smoking and in fact, make meaningful changes in marijuana use and heavy drinking. Future clinical trials should examine whether smoking cessation treatment that addresses both marijuana and tobacco smoking leads to substantial reductions in marijuana use.