Melissa C. Rothstein, University of Rhode Island


Co-use of alcohol and cannabis, or use of these substances simultaneously such that their effects overlap, is prevalent and growing. Compared to alcohol-only use, co-use of alcohol and cannabis is associated with greater negative consequences, such as heavier drinking, more cognitive issues, and risky behavior. Impulsivity (i.e., tendency toward rash action without consideration of consequences) and perceived norms (i.e., a social influence by which individuals adjust their behavior to that of their peers) are two factors related to increased substance use among young adults, but few studies have examined their role in co-use behaviors. Consequently, the purpose of this study was to examine the associations between impulsivity, perceived norms, co-use of alcohol and cannabis, and alcohol- and cannabis-related consequences. Participants were 209 (72.7% female) college students between 18 and 25 (M = 20.01, SD = 1.50) from universities in Rhode Island who completed an online survey regarding their co-use of alcohol and cannabis behaviors. A sequential mediation model was examined whereby impulsivity (positive urgency, negative urgency, sensation seeking, lack of premeditation, and lack of perseverance) predicted alcohol- cannabis-related consequences through the influence of perceived norms (i.e., descriptive and injunctive norms) and level of frequency of co-use of alcohol and cannabis. The overall indirect paths between each impulsivity facet and co-use consequences were nonsignificant. Findings revealed that higher injunctive norms predicted higher frequency of co-use of alcohol and cannabis. Higher negative urgency predicted co-use of alcohol and cannabis consequences. Lastly, higher lack of premeditation predicted lower co-use of alcohol and cannabis. All other paths were nonsignificant. Overall, this study informed an understanding of the relationships between impulsivity, norms, and co-use behaviors. Although the indirect paths in the sequential mediation model were nonsignificant, negative urgency was related to greater co-use consequences, and greater injunctive norms predicted greater frequency of co-use. Findings also elucidated nuances between alcohol-only, cannabis-only, and co-use variables among a sample of individuals who engage in co-use. Information may be used to inform interventions tailored to co-use of alcohol and cannabis.