Alcohol demand moderates brief motivational intervention outcomes in underage young adult drinkers

INTRODUCTION: The Alcohol Purchase Task (APT), a behavioral economic measure of alcohol's reinforcing value (demand), has been used to predict the effects of Brief Motivational Intervention (BMI) on alcohol use outcomes. However, it is not known whether BMI may be more or less efficacious, relative to control, among those with different levels of alcohol demand prior to treatment. METHODS: Non college-attending young adults (N = 150) reporting past-month heavy drinking were randomized to a single in-person session of BMI or a relaxation training control (REL). The BMI included delivery of personalized feedback and focused on developing discrepancy between the young adults' goals and their current pattern of alcohol use. At baseline, participants completed assessments of alcohol use and the APT. Drinking levels were re-assessed at 6 weeks and 3 months post-intervention. Demand indices derived from the APT were examined as moderators of treatment effects on follow-up drinking after covarying for baseline alcohol use. RESULTS: Two of four APT demand indices - intensity and O_max - moderated treatment outcomes. Relative to REL, BMI led to greater reductions in total number of drinks consumed and drinks per drinking day among participants with higher baseline alcohol demand. This association was not observed among participants with lower levels of alcohol demand. CONCLUSIONS: These results demonstrate that BMI may be particularly beneficial for those with a high reinforcing value of alcohol. The mechanism for this effect is unclear, and determining the process by which BMI confers increased benefit for these individuals is a fruitful area for future work.