Abstract
BACKGROUND: Behavioral economic theory predicts that low access to environmental reward is a risk factor for alcohol use disorder (AUD). The Substance-Free Activity Session (SFAS) is a behavioral economic supplement to standard brief alcohol interventions that attempts to increase environmental reward and may therefore have beneficial effects, particularly for individuals with low levels of environmental reward. METHODS: Participants were 393 college students who reported at least 2 heavy-drinking episodes in the past month. Participants were randomly assigned to 1 of 3 conditions following a baseline assessment: a standard alcohol-focused brief motivational intervention plus relaxation training session (BMI + RT), BMI plus Substance-Free Activity Session (BMI + SFAS), or an assessment-only control condition (AO). In a secondary analysis of the data from this study, we used person-centered statistical techniques to describe trajectories of alcohol severity and environmental reward over a 16-month follow-up and examined whether environmental reward levels moderated the effectiveness of the interventions. RESULTS: Piecewise growth mixture modeling identified 2 trajectories of reward availability: low increasing (LR; n = 120) and high stable (HR; n = 273). Depressive symptoms, cannabis use, sensation seeking, and low life satisfaction were associated with a greater probability of classification in the LR trajectory. Alcohol severity was greater in the LR trajectory than the HR trajectory. For students in the LR trajectory, at 1, 6, and 12 months, BMI + SFAS led to greater increases in reward availability and reduced levels of alcohol severity compared with the BMI + RT and AO conditions and at 16 months compared with AO. CONCLUSIONS: Young adults with low levels of environmental reward are at heightened risk for greater alcohol severity and may show greater benefit from brief alcohol interventions that focus on increasing substance-free reward than individuals who are not deficient in reward availability.