Examining the Impact of Simultaneous Alcohol and Cannabis Use on Alcohol Consumption and Consequences: Protocol for an Observational Ambulatory Assessment Study in Young Adults (Preprint)

BACKGROUND There is significant conflicting evidence as to how using cannabis while drinking alcohol (i.e., simultaneous alcohol and cannabis use) impacts alcohol volume consumed, patterns of drinking, and alcohol-related consequences. The impact of simultaneous use on drinking outcomes may be influenced by several within- (e.g., contextual) and between-person (individual) factors. OBJECTIVE The current study was designed to examine naturalistic patterns of alcohol and cannabis use in a sample of non-treatment seeking young adults who report simultaneous use alcohol and cannabis to understand how simultaneous use may impact drinking outcomes. The primary aims were to understand: 1) if simultaneous use is associated with increased alcohol consumption and riskier patterns of drinking; 2) if simultaneous use leads to increased alcohol consequences; and 3) how contextual circumstances moderate the impact of simultaneous use on consumption and consequences. METHODS Data collection involves a 28-day ambulatory assessment protocol in which participants complete ecological momentary assessments (EMA: random, event-contingent, and time-contingent surveys) of alcohol and cannabis use, contexts, motives, and consequences on their personal smartphones while continuously wearing an alcohol biosensor bracelet. Participants also complete a baseline assessment and brief virtual 14-day check-in and 28-day final sessions. RESULTS The project aimed to enroll 95 participants to obtain a target sample of 80 accounting for attrition. Recruitment and data collection began in May 2021 and is expected to continue through June 2024. Initial results for primary aims are expected in October 2024. As of March 2024, the project has recruited 118 eligible participants, 94 who have completed the study, exceeding initial projections in the study timeframe. Remaining recruitment will provide capacity to probe cross-level interactions that were not initially statistically powered. Strengths of the project include rigorous data collection, good retention and compliance rates, faster than expected enrollment procedures, use of a novel alcohol biosensor, and successful adaptation of recruitment and data collection procedures during the COVID-19 pandemic. CONCLUSIONS This is the first investigation to assess the key momentary predictors and outcomes of simultaneous use as well as self-reported and objective (via alcohol biosensor) measures of alcohol consumption and patterns. The results of this study will inform prevention efforts and studies of individuals who use cannabis who are engaged in alcohol treatment. CLINICALTRIAL https://doi.org/10.17605/OSF.IO/S4BYZ