Reefer madness or much ado about nothing? Cannabis legalization outcomes among young adults in the United States.

In 2012, Colorado became one of the first two U.S. States to legalize cannabis for recreational use for adults 21 and older. Given that cannabis use holds potential physical and mental health risks, particularly among adolescent users, concerns have grown regarding changes in use following this change in policy. Studies examining medical cannabis legalization have found inconsistent changes in cannabis use and prevalence of dependence following medical implementation. However, recreational legalization holds potential unique changes, such as increased availability and social acceptance, as well as decreased price and perceived harm of use. There also may be increased interest in moving to Colorado related to the changes in cannabis laws. Based on past literature, two hypotheses were made for this study. First, college student cannabis use would increase after recreational legalization, however just for those 21 years old and older. Second, there would be a positive relation between the influence of cannabis legislation on out-of-State student's decision to attend a Colorado university and their cannabis use. Data from 5241 undergraduate students was available to test study hypotheses using Pearson's Chi-square, negative binomial regressions, and path analysis. Results indicated that cannabis use increased since recreational legalization for all students, but more so for those over 21 years. No differences in past month use frequency were found between pre- and post-legalization. Influence of cannabis laws on non-resident student's decision to attend a Colorado college predicted lifetime and past 30-day use. Additionally, out-of-State students reported higher past 30-day use than in-State students. These findings may help inform other States considering recreational legalization of potential outcomes, as well as potential interventions.