Medicinal cannabis use among young adults during California's transition from legalized medical use to adult-use: a longitudinal analysis.

Background: In 2016, California transitioned from legalized medical cannabis use to adult-use. Little is known about how this policy change affected medicinal cannabis use among young adults.Objectives: To identify longitudinal groups of medicinal cannabis users and concurrent changes in health- and cannabis use-related characteristics among young adults in Los Angeles between 2014 and 2021.Methods: Cannabis users (210 patients and 156 non-patients; 34% female; ages 18-26 at baseline) were surveyed annually across six waves. Longitudinal latent class analysis derived groups from two factors - cannabis patient status and self-reported medicinal use. Trajectories of health symptoms, cannabis use motives, and cannabis use (daily/near daily use, concentrate use, and problematic use) were estimated across groups.Results: Three longitudinal latent classes emerged: Recreational Users (39.3%) - low self-reported medicinal use and low-to-decreasing patient status; Recreational Patients (40.4%) - low self-reported medicinal use and high-to-decreasing patient status; Medicinal Patients (20.3%) - high self-reported medicinal use and high-to-decreasing patient status. At baseline, Medicinal Patients had higher levels of physical health symptoms and motives than recreational groups (p < .05); both patient groups reported higher level of daily/near daily and concentrate use (p < .01). Over time, mental health symptoms increased in recreational groups (p < .05) and problematic cannabis use increased among Recreational Patients (p < .01).Conclusions: During the transition to legalized adult-use, patterns of medicinal cannabis use varied among young adults. Clinicians should monitor increases in mental health symptoms and cannabis-related problems among young adults who report recreational - but not medicinal - cannabis use.