Differences in alcohol and cannabis motives among simultaneous, concurrent, alcohol-only, and cannabis-only users
Authors: Berry Katherine , Looby Alison 
Published: September 2022

Substance use motives are strong predictors of alcohol and cannabis use and consequences among college students. Both simultaneous alcohol and cannabis (i.e., marijuana; SAM) and concurrent alcohol and cannabis (i.e., marijuana; CAM) use are associated with higher endorsement of certain types of motives compared to single drug-only use, which may explain heightened risks for experiencing negative consequences evidenced by co-users. Understanding whether motives differ according to type of use could provide an important avenue for intervention efforts; however, research has not yet examined if motives differ between SAM and CAM users. Thus, the purpose of this study was to examine how SAM, CAM, and single drug-only users differ on alcohol and cannabis motives. Participants were 2295 college students (72.4% female, 50.6% white) from seven US universities who reported past-month alcohol and/or cannabis use (41.2% SAM, 12.4% CAM, 39.1% alcohol-only, 7.3% cannabis-only). Participants completed measures of alcohol and cannabis motives and past-month substance use frequency via online survey. Two multivariate analyses of covariance (MANCOVA) models were conducted to examine differences on cannabis motives (i.e., enjoyment, celebration, conformity, and coping) and alcohol motives (i.e., social, coping, enhancement, and conformity) separately by past-month user status, controlling for sex and frequency of use. The overall cannabis model was significant, with between-group effects on conformity (F(2,1398)=3.90, p=.02), coping (F(2,1398)=6.96, p=.005), and celebration (F(2,1398)=5.83, p=.015) motives. Pairwise comparisons utilizing a Bonferonni-corrected alpha (p<.017) indicated that SAM users endorsed greater coping (p=.002) and celebration (p=.004) motives than CAM users. Moreover, cannabis-only users held greater coping motives than CAM users (p=.009). SAM and cannabis-only users did not differ on any motives. The overall alcohol model was also significant, with between-group effects on all four alcohol motives. Pairwise comparisons indicated that SAM users endorsed greater social (p=.012), coping (p=.003), and enhancement (p<.001) motives than CAM users. Moreover, SAM users were higher on all four motives (all ps<.01) than alcohol-only users, and CAM users were higher on social motives (p=.013) than alcohol-only users. Results indicate that SAM and CAM users can be importantly differentiated by alcohol and cannabis motives, with SAM users reporting greater motives for use related to coping with negative mood and enhancing positive mood/celebrating for both substances. Interestingly, SAM users did not differ from single drug-only users on cannabis motives, though they uniformly reported greater alcohol motives. Given that SAM users reported stronger enhancement and coping motives than CAM users across both drugs, it is possible that college students may opt to combine their substances when they are predominantly motivated to use for mood-related reasons. Considering that SAM users only differed from single-drug users with regard to alcohol, but not cannabis motives, it may be that simultaneous use particularly enhances alcohol-related desirable outcomes, though not necessarily desirable cannabis outcomes. As such, intervention efforts designed to reduce SAM use may benefit from specifically targeting alcohol and mood-related motives. Moreover, research is needed to examine the within-person effects that motives may have on type of use.