Changes in psychosis-related emergency department and hospitalization rates among youth following cannabis legalization in Colorado.

An increasing number of U.S. states have legalized cannabis, but the effect on adolescent and young adult psychosis-related hospitalizations remains under-studied. Using data from Denver Health between 2005 and 2020, we examined associations between implementation of the Ogden Memo (expanding use of medical cannabis in Colorado, October 2009) and Amendment 64 (legalizing adult-use cannabis in Colorado, November 2012) and trends in psychosis-related emergency department and hospital visits with and without cannabis use disorder (CUD) among youth aged 10-29. Patients with psychosis hospitalizations were predominately male (68 %), white (53 %), and Medicaid recipients (59 %). Significant increases (p < 0.05) were observed in the monthly average rate of psychosis hospitalizations between pre-Ogden memo (21.9 per 100,000) and post-Ogden memo pre-legalization (28.0 per 100,000) and post-legalization (32.3 per 100,000). Similarly, significant increases (p < 0.05) were observed in the monthly average rate of psychosis hospitalizations involving CUD between pre-Ogden memo (2.0 per 100,000), post-Ogden memo and pre-legalization (3.4 per 100,000), and post-legalization (8.5 per 100,000). Interrupted time series modeling found a significant difference in the trends for psychosis hospitalizations involving CUD following recreational legalization (change in average monthly rate went from 0.02/100,000 (95 % CI -0.02, 0.06) to 0.11/100,000 (95 % CI 0.09, 0.13), (difference (0.09 (95 %CI 0.05, 0.14)). Findings suggest an increase in overall hospital encounters for psychosis among youth after the legalization of recreational cannabis. Given the adoption of increasingly permissive cannabis laws, there is a need to plan effective public health responses that could mitigate unintended consequences related to cannabis use.