Mechanisms and moderators of intervention efficacy for soldiers with untreated alcohol use disorder.

OBJECTIVE: This research evaluates changes in perceived military and civilian drinking norms as mechanisms of the effects of a motivational enhancement therapy (MET) intervention on changes in alcohol consumption among active-duty military personnel with a substance use disorder. We also evaluate the value of providing tolerance and family history risk-related personalized feedback by testing whether those receiving feedback indicating higher risk reduce their drinking more than those receiving feedback indicating lower risk or receiving no feedback. METHOD: Participants (N = 242; Mage = 28 years; 92% male; 59% Caucasian) completed a baseline questionnaire and were randomly assigned to a MET or educational control condition. Both conditions were single session and took place over the telephone. Outcomes were assessed 3 and 6 months later. The study was preregistered at ClinicalTrials.gov (NCT01128140). RESULTS: We found evidence that reductions in perceived norms for other military personnel, but not for civilians, mediated intervention efficacy on reductions in alcohol use. Further, the MET intervention was successful at reducing drinking among soldiers who reported higher levels of baseline tolerance and family history risk, but not succuessful at reducing drinking among those who reported low or medium levels of risk. CONCLUSIONS: Systematic evaluation of whether and how individual intervention components contribute to efficacy is a promising approach for refining and improving interventions. This research suggests that MET interventions may wish to target focal perceived norms and provides support for discussion of feedback indicating elevated risks due to tolerance and family history. (PsycINFO Database Record (c) 2020 APA, all rights reserved).