Up to one-third of young adults report use of marijuana or alcohol in the past month, with sizable numbers reporting daily marijuana use and heavy episodic drinking. Simultaneous alcohol and marijuana (SAM) use, defined as use of both substances at the same time or within a few hours of each other with overlapping effects, is common among young adults. Recent research has shown that SAM use leads to greater negative consequences compared to use of either substance alone. No current intervention addresses SAM use specifically and few leverage new technological methods (e.g., smartphones) or strategies (e.g., protective behavioral strategies \[PBS\]) to engage young adults.

The goal of this Stage I treatment development project is to develop a fully mobile adaptive ecological momentary intervention (a-EMI) titled "Smartphone App For Effectively Reducing Risk (SAFERR)" that is grounded in self-regulation and social cognitive theories. To determine the most efficacious intervention strategies, the investigators will test variations of intervention components to identify the best combination. They will assess the feasibility and efficacy of intervention components on two outcomes (negative consequences and PBS) using a fractional factorial experimental design.

The study will take place at the Center for Integrated Health Care Research at Kaiser Permanente Hawaii (KPHI), located in Honolulu (island of Oahu). Following pilot testing, the SAFERR a-EMI will be administered to 6 eligible participants. Based on the feedback, the app will be revised and a trial of the SAFERR intervention will begin. 136 diverse young adults who report current SAM use will be recruited from primary care clinics at KPHI. Eligible individuals will complete a baseline assessment and then be randomly assigned (by sex) to one of eight conditions using stratified randomization. Each condition either includes or does not include four different intervention strategies focused on craving reduction and PBS. All participants will complete signal-contingent (random prompts three times per day) and event-related ecological momentary assessment (EMA) for 6 weeks using a smartphone application (app). EMA will continue during the 4-week intervention phase. At the beginning of the intervention, all participants will complete an introduction module via the study app that includes psychoeducation, personalized feedback, and goal setting. Participants will then begin the a-EMI via the study app, with components delivered based on their condition assignment.

Following completion of the intervention, participants will complete a post-intervention assessment and follow-up assessments at one- and three-months. The feasibility of the a-EMI and design will be examined by assessing: study attrition and response rates/time, module completion rates, acceptability (satisfaction, usability), perceived helpfulness, goal attainment, and implementation and intervention engagement. The efficacy of intervention components on negative consequences and PBS during EMA and at post-intervention and one-month and three-month follow-ups will be examined. In a future, larger study, the most useful components will be incorporated into a full intervention package and tested in a randomized controlled trial.