Cannabis Legalization Linked to More Cannabis Use Disorder and Poisoning Diagnoses

Among 110 million commercially insured adults (2011-2021), medical cannabis laws were associated with increases of 31.09 CUD diagnoses and 0.76 cannabis poisoning diagnoses per 100,000 enrollees per quarter. Recreational cannabis laws were associated with 0.34 additional cannabis poisoning diagnoses per quarter. CUD increases were larger among women and adults aged 35-44. Opening medical dispensaries or allowing home cultivation did not show significant independent effects.

Staggered adoption difference-in-differences analysis using the Merative MarketScan Commercial Claims database (2011-2021) across all 50 states and DC. Event studies estimated magnitude by year-quarter relative to policy implementation. Subgroup analyses by sex and age.

Published in JAMA Psychiatry, this is one of the largest and most rigorous studies linking cannabis policy changes to clinical diagnoses, using claims data from over 110 million commercially insured adults.

While cannabis use increases modestly after legalization, this study shows the downstream clinical consequences (diagnosed CUD and poisoning) are measurable at the population level and concentrated in demographics not traditionally considered high-risk for cannabis problems.

Commercially insured population may not represent uninsured or Medicaid populations. Cannot distinguish whether increased diagnoses reflect more CUD or more clinical detection due to reduced stigma. Claims data may include coding changes over time. Sensitivity analysis confirmed results held when excluding COVID-era data.