The Impact of Cannabis Legalization and Availability on the Frequency and Health Services Utilization for Psychotic Disorders: Population-Based Evidence to Inform Policy Initiatives

Psychotic disorders have a profound impact on the lives of young people. The symptoms of psychosis may include delusions, hallucinations, and erratic or unusual behavior. The onset of these symptoms usually occurs in adolescence and young adulthood, which has a big impact on a person’s social, educational, and career development.

We know that the use of cannabis can increase the chances that a person develops a psychotic disorder. The risks are particularly high for people who start using cannabis at an early age, for those who use cannabis frequently, people with a family history of psychotic disorder, and those who use high-potency cannabis. There is a concern that the legalization of cannabis may lead to more people using cannabis, resulting in a greater number of psychotic disorders across the population.

This project used data from the health care system in Ontario to see whether there were a greater number of cases of psychotic disorders after the legalization of cannabis, during a period with strict restrictions on the number of retailers and types of products available. We also mapped the location of cannabis retail stores across the province to examine whether there were higher rates of health service use for psychosis in areas where cannabis retailers were located. These findings will help to inform public health professionals and decision makers about the potential harms of cannabis legalization, so that policies can be put in place to protect the mental health of Canadians.

Project participants

Funding: Canadian Institutes of Health Research and the Mental Health Commission of Canada (Cannabis and Mental Health Catalyst Grant)

Principal Investigator: Kelly Anderson

Staff: Rebecca Rodrigues

Co-Investigators: Suzanne Archie, Jordan Edwards, Tara Elton-Marshall, Jason Gilliland, Daniel Myran, Robin Murray, Lena Palaniyappan, Chris Perlman, Jamie Seabrook, Salimah Shariff

Students: Maliha Mamun, Jared Wootten