Effects of legalizing recreational cannabis sales on cannabis use and cannabis-related disorder among presentations to a psychiatric emergency service.

Introduction: Limited research exists on the impact of changing cannabis policies on psychiatric populations, who are especially vulnerable to the negative effects of substance use. This study examined changes in cannabis use and cannabis-related disorders across age groups of psychiatric emergency presentations following the start of recreational cannabis sales in Massachusetts.

Methods: Cross-sectional electronic health records from 7350 unique presentations to a psychiatric emergency service in a tertiary care hospital in Massachusetts were analyzed. Logistic regressions estimated changes in rates of urine tetrahydrocannabinol (THC) positivity and cannabis-related disorder ICD-10 diagnosis codes (F12.X) from pre-commercialization (01/01/2017-11/19/2018) to post-commercialization (11/20/2018-12/31/2019) across different age groups (12-17, 18-25, 26-49, 50-70 years), controlling for sex, race, and ethnicity.

Results: Rates of THC positivity increased significantly from pre- to post-commercialization (32.4% to 36.3%, p<.001), but not rates of cannabis-related disorder (10.5% to 11.7%). Adolescents (12-17 years) had the largest increase in THC positivity (5% to 17.3%, AOR=4.32 [2.15, 8.68]) whereas adults (26-49 years) experienced a modest increase (37.7% to 42.5%, AOR=1.24 [1.08, 1.42]). Only the adolescent group had a significant increase in cannabis-related disorders (3.2% to 12.1%, AOR=4.63 [1.97, 10.87]).

Conclusions: Commercialization of recreational cannabis sales may disproportionately affect adolescents with psychiatric illnesses or vulnerabilities, resulting in an increased need for psychiatric emergency care. Further research is needed to examine the impact of cannabis policies on this population to inform targeted prevention efforts.