Marijuana Legalization in Colorado: Increasing Potency, Changing Risk Perceptions, and Emerging Public Health Concerns for Youth.

Background: Marijuana legalization occurred gradually in Colorado through political processes. Objectives: This review aimed at describing the history of marijuana legalization and correlated shifts in product availability, use patterns, and risk perceptions and describes associated emerging concerns with this process for adolescents and young adults. Methods: This review focuses on the history of marijuana legalization and correlated shifts in product availability, use patterns, and risk perceptions. Results: Along with the legalization of marijuana, there has been strong commercialization characterized by the widespread development of dispensaries, new products including edibles and concentrates, and an overall lowering of the "price per serving" of marijuana. While the frequency of marijuana use among adolescents does not appear to have shifted substantially, young adult patterns of use have demonstrated an increase in usage. A substantial shift has occurred in the increasing use of concentrates and high potency products. Emerging concerns related to high potency products include increased acute care visits, prevalence and outcomes of comorbid mental health disorders, cannabis-induced psychosis, driving while high, marijuana-related lung injuries, and increased use during pregnancy. Yet, there are also potential medical uses of marijuana. Conclusion: To date, scientific evidence of the mental or physical effects of high potency products is currently very limited. Clinical issues related to the treatment of marijuana use and comorbid psychiatric disorders in youth are discussed with a focus on how low risk perceptions influence treatment considerations.