Associations between marijuana use patterns and recreational legislation changes in a large Colorado college student sample

Background: Many states in the U.S. have changed how they regulated medicinal and/or recreational marijuana. Understanding the impact of these policy changes on marijuana use and perceptions of acceptability and safety of use is needed. The current study examined perceptions and patterns of marijuana use among college students, a population at increased risk for initiation and heavy use. Method: Data include Colorado university students and national sample averages. We used repeated cross-sectional analyses to examine responses to the American College Health Association National College Health Assessment and added marijuana measures. We examined differences in use and norms pre- to post-legalization among Colorado college students. Colorado data were also compared to national summary statistics. Results: Social norms, use initiation, and use recency and frequency in Colorado increased significantly across changes in recreational legislation. Descriptive norms and rates of ever users in Colorado increased faster than national averages. Conclusions: Results suggest recreational legalization increases how quickly social norms become more approving. As marijuana policy continues to change, implementing social norms interventions alongside legislative changes may offset increases in risk for use initiation and frequency by countering increased social norms favorable to use.