Mental Health, Physical Health, and Social Support As Predictors of Concurrent Use of Alcohol and Marijuana in College Students

Background and Purpose:  The concurrent use of alcohol and marijuana (i.e., concurrent polysubstance use; CPU) is prevalent on college campuses.  Compared to use of alcohol only, CPU is associated with increased risk of substance related problems and higher quantities of alcohol use.  Despite being prevalent, the predictors of CPU among college students are relatively unknown.  Mental health, physical discomfort, social support and demographics have been associated with alcohol and marijuana use in college students.  This prospective study investigated these domains as predictors of CPU, which could aid in the targeting of prevention efforts for CPU on college campuses.

Methods:  This secondary analysis utilized data from a longitudinal prospective cohort study of undergraduate students recruited from a large, public, mid-Atlantic university (N=829).  Participants completed annual in-person interviews and questionnaires; this study utilized freshman year data (Time 1) to predict CPU during sophomore year (Time 2).  At Time 1, participants completed questions regarding lifetime diagnosis of ADD/ADHD (no/yes), anxiety, depression, experience with conduct problems (prior to age 18), personal assessment of overall health (excellent/good/fair/poor), social support from friends and family, peer relationships, gender, and race/ethnicity (White/African American/Asian/Other/Hispanic).  Participants were classified as alcohol-only users (0) or CPU (1) according to their past 30-day use of alcohol and marijuana at Time 2.  Using logistic regression, use category was regressed on gender, race/ethnicity, ADD/ADHD, health, and total scale scores for anxiety, depression, conduct problems, support from friends, support from family, and peer relationships.

Results:  Forty-six percent of the sample reported CPU during sophomore year.  Analyses indicated that gender, race/ethnicity, depression, conduct problems, and social support from friends at Time 1 were significant predictors of CPU at Time 2.  Males were 1.5 times as likely to engage in CPU (B=.412; p=.01; CI 1.104, 2.065).  African American (B= -1.069, p=0001; CI .181, .653) and Asian (B = -.692, p=.001; CI .285, .880) participants were significantly less likely to engage in CPU.  As depression scores increased, the likelihood of engagement in CPU also increased (B=.056; p=.028; CI 1.006, 1.111).  Past experience with conduct problems significantly increased the likelihood of engagement in CPU (B=.038, p=.026, CI 1.005, 1.075).  Finally, as social support from friends increased, the likelihood of engagement in CPU decreased (B= -.076; p=.013, CI .873, .984).

Conclusions and Implications:  College campuses could target specific campus prevention interventions to freshman students, which may decrease the likelihood of engagement in CPU as college careers progress.  Prevention efforts for CPU could initiate screening and intervention though on-campus mental health services during freshman year, especially for students with higher self-reported depression and/or past conduct problems.  On-campus activities and services that promote initiation and continuation of healthy peer relationships during freshman year could facilitate increased social support, which may influence future CPU in students with low perceived peer support. Consistent with prior research, males engaged in CPU more than females.  This study found a gender disparity in CPU rates, which was contrary to previous research that utilized bivariate analyses; gender as a potential risk factor for CPU should be studied further.