Cannabis Involvement in PTSD Emergency Visits Rose 151% During Canada's Legalization Era

Among 381,450 PTSD ED visits in Ontario, cannabis co-involvement increased by 151% (from 0.13 to 0.33 per 100,000) between the first and last cannabis policy periods, while alcohol co-involvement increased by 58%. However, the increase was a steady upward trend not clearly tied to specific policy changes, suggesting normalization and increased access rather than legalization itself drove the increase.

Repeated cross-sectional study using Ontario health administrative data identifying all ED visits for PTSD among residents aged 10-105 from 2008-2022 (15.7 million total). Cannabis and alcohol co-diagnoses were tracked across four cannabis policy periods, analyzed using Poisson models.

People with PTSD are at elevated risk for cannabis use disorder. This population-level data shows that as cannabis access expanded, cannabis-related complications in PTSD patients grew substantially faster than alcohol-related complications, highlighting a population that may need targeted intervention.

PTSD and cannabis use have a complicated relationship: some patients report symptom relief, but cannabis use disorder rates are elevated in this population. The steady increase in cannabis-PTSD ED visits regardless of specific policy changes suggests that broader cultural shifts toward cannabis normalization, rather than legislation alone, are driving increased use among this vulnerable population.

Administrative data using ICD codes may undercount both cannabis involvement and PTSD. Cannot determine whether cannabis contributed to the ED visit or was incidentally documented. Cannot assess whether patients were using cannabis therapeutically or recreationally. Ontario-specific findings.