Abstract
OBJECTIVE: This study compared the efficacy of mindfulness-based relapse prevention (MBRP) with relapse prevention (RP) on reducing alcohol consumption. Secondary, exploratory aims assessed moderation of treatment effects by sex and cannabis use. METHOD: A total of 182 individuals (48.4% female; 21-60 years old) who reported drinking more than 14/21 drinks/week (for women and men, respectively) in the past 3 months but who wished to quit/reduce their drinking were recruited from Denver and Boulder, Colorado. Individuals were randomly assigned to 8 weeks of individual-based MBRP or RP treatment. Participants completed substance use assessments at baseline, halfway through and at the end of treatment, and 20 and 32 weeks after treatment. Primary outcomes were Alcohol Use Disorders Identification Test-consumption questions (AUDIT-C) scores, heavy drinking days (HDD), and drinks per drinking day (DDD). RESULTS: Across treatments, drinking decreased over time (ps < .001), with a significant time-by-treatment interaction found for HDD (F = 3.50, p < .01). HDD initially decreased in both treatments but remained stable or increased after treatment for MBRP and RP participants, respectively. At follow-up, MBRP participants had significantly less HDD than RP participants. Sex did not moderate treatment effects (ps > .17), whereas cannabis use moderated treatment effects on DDD and HDD (F = 4.89, p < .001, and F = 4.30, p < .005, respectively). High cannabis use frequency was associated with continued posttreatment decreases in HDD/DDD for MBRP participants but increased HDD for RP participants. At low cannabis use frequency levels, HDD/DDD remained stable after treatment across groups. CONCLUSIONS: Drinking decreases were comparable across treatments, but HDD improvements diminished for RP participants after treatment. In addition, cannabis use moderated treatment efficacy for HDD/DDD.