Longitudinal findings from a randomized clinical trial of naltrexone for young adult heavy drinkers

Objective: Behavioral interventions for young adults show limited effects 1-year posttreatment. Few studies have examined the longitudinal outcomes of pharmacotherapy trials to reduce heavy drinking. This study examined the posttreatment, longitudinal effects of the first placebo-controlled trial of naltrexone in young adult heavy drinkers. Method: Randomized, double-blind, placebo-controlled, 8-week trial. Follow-up assessments at posttreatment (8 weeks [8W]), 3 months [3M], 6 months [6M], and 12 months [12M]). Participants were young adults ages 18-25 (N = 118) who reported ≥4 heavy drinking days in the prior 4 weeks. Outcomes were percent days heavy drinking (PHDD), percent days abstinent (PDA), and drinks per drinking day (DPDD). Results: There were no time effects on PHDD. Treatment improvements were maintained posttreatment. A main effect of time was found for PDA. Both conditions continued to increase PDA posttreatment. For DPDD, a Treatment xTime interaction emerged. In the naltrexone condition, DPDD increased from 8W to 6M and decreased from 6M to 12M, resulting in no net change posttreatment. The placebo group had a nonsignificant decrease in DPDD. The result was a significant benefit of naltrexone at 8W but not 12M. Conclusions: Participants showed improvements or no change on most outcomes over 1 year posttreatment. Naltrexone had significant benefits over placebo at 8W. Although differences among groups diminished during follow-up, overall effects were maintained. Behavioral monitoring during treatment may impact long-term outcomes more than a single intervention following discontinuation of active medication.