Young adult concurrent use and simultaneous use of alcohol and marijuana: A cross-national examination among college students in seven countries

Introduction: Many young adults report frequent co-use of alcohol and marijuana, with some individuals engaging in simultaneous use (SAM; use of both substances within the same occasion resulting in an overlap of their effects) and others in concurrent use (CAM; use of both substances during a similar time period [e.g., past 30 days] but not within the same occasion). Emerging work demonstrates that SAM relative to CAM use places individuals at a greater risk for substance-related harms; however, these results primarily rely on U.S. samples. The goal of the present multi-country study was to examine prevalence rates of CAM and SAM use and examine differences in past 30-day SAM/CAM use on alcohol/marijuana substance-related outcomes among college students from seven countries. Methods: A total of 9171 (70.5% women; Mean age = 20.28, SD = 3.96) college students participated in the cross-sectional online survey study. Results: Among students who endorsed use of both alcohol and marijuana in the past 30-days (n = 2124), SAM use (75.8%) was far more prevalent than CAM use (24.2%). Moreover, ∼75% of students endorsed SAM use within each country subsample. Regression models showed that SAM vs. CAM use was associated with greater alcohol and marijuana use and negative consequences. Conclusions: College students from around the world endorse high rates of SAM use, and this pattern of co-use is associated with greater frequency of use and substance-related harms. On college campuses, SAM use should be a target of clinical prevention/intervention efforts and the mechanisms underpinning the unique harms of SAM need to be clarified.Fil: Bravo, Adrian J.. College of William and Mary; Estados UnidosFil: Prince, Mark A.. State University of Colorado at Boulder; Estados UnidosFil: Pilatti, Angelina. Universidad Nacional de Córdoba. Instituto de Investigaciones Psicológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Psicológicas; ArgentinaFil: Mezquita, Laura. Universitat Jaume I; EspañaFil: Keough, Matthew T.. University of York; Reino UnidoFil: Hogarth, Lee. University of Exeter; Reino Unid