Simultaneous Use of Alcohol and Marijuana Among College Students: The Role of Expectancies, Impulsivity and Behavioral Emotion Regulation

<i>Background:</i> The simultaneous use of alcohol and marijuana (SAM, using both substances on the same occasion) leads to increased risk of negative outcomes compared to single-substance use. Impulsivity is a recognized risk factor for SAM use, yet less is known about the roles of behavioral emotion regulation and SAM-related expectancies. <i>Objectives:</i> We examined if recent SAM users could be distinguished from alcohol-only users and nonusers based on impulsivity traits, behavioral emotion regulation strategies, and outcome expectancies related to SAM use. We also assessed if frequency of alcohol use and related negative consequences, and binge drinking varied between SAM and alcohol-only users. <i>Methods:</i> Argentinean college students (<i>n</i> = 1369, ages 18-25) completed an online survey assessing substance use, impulsivity, behavioral emotion regulation, SAM-related expectancies, and SAM-related negative consequences. SAM vs. alcohol-only vs. nonuse comparisons were conducted <i>via</i> ANOVAs and multinomial logistic regressions (to examine the role of each included variable to distinguish across groups). <i>Results:</i> SAM users reported significantly higher binge drinking frequency and alcohol-related problems than alcohol-only users. Sensation seeking, low perseverance, and low withdrawal were associated with SAM use. Stronger positive and weaker negative SAM-related expectancies differentiated SAM users from both nonusers and alcohol-only users. <i>Conclusions:</i> The findings highlight the combined roles of impulsivity, behavioral emotion regulation, and SAM-related expectancies in differentiating SAM users from alcohol-only or nonusers. These results have implications for targeted interventions in college populations, especially underrepresented populations such as Latin American college students.