State Cannabis and Alcohol Policy Environments: Associations With College Students' Use of Cannabis, Alcohol, and Both Substances.

Abstract

Cannabis policies differ between states that have legalized cannabis use and within states over time after legalization milestones. A continuous measure of state cannabis policy environments was examined in relation to college students' cannabis and alcohol use, accounting for concurrent state alcohol policies. Undergraduates (N=902,486) aged 18-24 years from 591 four-year institutions in 47 states completed a cross-sectional survey between 2008 and 2019. Time-varying, state-level Cannabis Policy Scale and Alcohol Policy Scale scores were sums of 17 and 29 policies, respectively, weighted by efficacy and state-level implementation. Outcomes were any 30-day use and frequent use (≥20 days) of cannabis and alcohol, 2-week binge drinking (≥5 drinks in a sitting), and co-use (binge drinking and frequent cannabis use). Data were analyzed in 2024-2025. Higher Cannabis Policy Scale scores (greater restrictiveness) were associated with significantly lower odds of cannabis use, frequent cannabis use, and co-use (OR=0.97 [0.96-0.98]; 0.93 [0.91-0.94]; and 0.94 [0.92-0.96], respectively) but not significantly associated with alcohol use outcomes. Higher Alcohol Policy Scale scores were significantly associated with lower odds of every cannabis, alcohol, and co-use outcome. Cannabis Policy Scale and Alcohol Policy Scale effects generally were significant for underage students (aged 18-20 years) but stronger for older students (aged 21-24 years). Under less restrictive state cannabis and alcohol policy regimes, college students were more apt to use cannabis and alcohol frequently and concurrently. To improve students' well-being, campus- and community-level policymakers can build on strong state policy environments or compensate for weak ones, using Alcohol Policy Scale and Cannabis Policy Scale as tools to identify these needs.