Descriptive norms and expectancies as mediators of a brief motivational intervention for mandated college students receiving stepped care for alcohol use.

Stepped care approaches for mandated college students provide individual brief motivational interventions (BMI) only for individuals who do not respond to an initial, low-intensity level of treatment such as Brief Advice (BA). However, how BMIs facilitate change in this higher-risk group of mandated students remains unclear. Perceived descriptive norms and alcohol-related expectancies are the most commonly examined mediators of BMI efficacy but have yet to be examined in the context of stepped care. Participants were mandated college students (N = 598) participating in a stepped care trial in which mandated students first received BA. Those who reported continued risky drinking 6 weeks following a BA session were randomized to either a single-session BMI (N = 163) or an assessment-only comparison condition (AO; N = 165). BMI participants reduced alcohol-related problems at the 9 month follow up significantly more than AO participants. Multiple mediation analyses using bootstrapping techniques examined whether perceived descriptive norms and alcohol-related expectancies mediated the observed outcomes. Reductions in perceptions of average student drinking (B = -.24; 95% CI [-.61, -.04]) and negative expectancies (B = -.13; 95% CI [-.38, -.01]) mediated the BMI effects. Furthermore, perceived average student norms were reduced after the BMI to levels approximating those of students who had exhibited lower risk drinking following the BA session. Findings highlight the utility of addressing perceived norms and expectancies in BMIs, especially for students who have not responded to less intensive prevention efforts.