Marijuana Use and Increases in Use over Time among Young Adult College Students in the State of Georgia: Analyses of Sociocontexual Predictors

Background: While research has assessed correlates of marijuana use, there has been less focus on predictors of differing levels of changes in use during young adulthood, a critical period for use/escalation. Objectives: We examined changes in marijuana use and related sociocontextual predictors (e.g., earlier-onset substance use, parental use, college type). Methods: Using data from Georgia college students (ages 18–25 years) in a 2-year, 6-wave longitudinal study (64.6% female, 63.4% White), 2-part random-effects modeling examined use at any assessment and number of days used. Results: Predictors of use status at any assessment included being male (OR = 1.87, 95%CI = [1.28–2.73]), Black (OR = 1.91, 95%CI = [1.15–3.19]), earlier-onset marijuana (OR = 2.63, 95%CI = [1.70–4.06]), cigarette (OR = 2.04, 95%CI = [1.19–3.48]), and alcohol users (OR = 1.49, 95%CI = 1.00–2.22]), parental tobacco (OR = 2.14, 95%CI = [1.18–3.86]) and/or alcohol use (OR = 1.55, 95%CI = [1.09–2.20]), and attending private (vs. public) institutions (OR = 1.68, 95%CI = [1.10–2.59]). Predictors of lower likelihood of use over time included being male (OR = 0.87, 95%CI = [0.77–0.98]), earlier-onset cigarette use (OR = 0.82, 95%CI = [0.68–0.98]), parental alcohol use (OR = 0.86, 95%CI = [0.77–0.97]), and private institution students (OR = 1.17, 95%CI = [1.02–1.34]). Predictors of more days used at baseline included being male (OR = 1.77, 95%CI = [1.40–2.23]), Black (OR = 1.42, 95%CI = [1.04–1.93]), earlier-onset marijuana (OR = 2.32, 95%CI = [1.78–3.01]) and alcohol users (OR = 1.29, 95%CI = [1.01–1.66]), and parental tobacco use (OR = 1.90, 95%CI = [1.32–2.73]). Predictors of fewer days used over time included being older (OR = 0.98, 95%CI = [0.97–1.00]), parental tobacco use (OR = 0.86, 95%CI = [0.78–0.95]), and attending private institutions (OR = 0.89, 95%CI = [0.83–0.93]). Conclusions: Intervention efforts can be informed by current findings that correlates of baseline use (e.g., being male, attending private institutions) also predicted less use over time, and one’s earlier use and parents’ use of various substances impacted young adult use.