Bloustein School hosts Daniel Myran, discusses cannabis legalization effects in Canada

On Wednesday, the Edward J. Bloustein School of Planning and Public Policy hosted "Changes in Healthcare Visits Due to Cannabis Use Following Legalization of Non-medical Cannabis in Canada with Daniel Myran," a presentation in the New Jersey Alliance for Clinical and Translational Science Special Populations Core 2024 Seminar Series, according to an announcement by the Bloustein School.

At the event, Daniel Myran, a clinician scientist and assistant professor in the Department of Family Medicine at the University of Ottawa in Ottawa, Canada, unveiled his latest findings on the impacts of cannabis legalization in Canada.

Sponsored by the Canadian government and the Canadian Center on Substance Use and Addiction, Myran's research delves into the outcomes of Canada's shift from cannabis prohibition to having a regulated market since 2018. 

Myran's study uses administrative data and natural experiments to trace the evolution of cannabis policy and its implications for mental health and substance use within health care systems.

The study outlines a significant increase in emergency room visits related to cannabis use since 2010 in Ontario, the most populated province in Canada. This rise aligns with the province's timeline of cannabis policy reform announcements and the adjustments to medical cannabis accessibility, according to Myran.

He said the fluctuation in health care visits reflects the development stages of the legal cannabis market. Initially, with strict market controls in place, such as the relatively low number of stores and placement of products with minimal tetrahydrocannabinol (THC), the number of cannabis-related health care visits stabilized.

"During the period of time that the market begins to rapidly expand with new products and higher numbers of stores, which is also when the COVID-19 pandemic happens, you do see an uptick (in visits)," Myran said.

Government research also indicates that from 2010 to 2022, the number of Canadians reporting cannabis use nearly tripled, he said.

Addressing wider concerns around a potential connection between cannabis and psychosis, Myran said he has observed the number of emergency room visits pertaining to reports of cannabis-related psychosis, as well as whether these patients go on to develop schizophrenia.

The results of these studies found that cannabis-induced psychosis rates rose 250 percent over approximately the last decade and, additionally, a person with one case of cannabis-related psychosis has a 26 percent chance of developing schizophrenia within three years compared to 0.1 percent for a person who has not had that experience, according to Myran.

"Even if you start adjusting out for a little variance to their socioeconomic status, whether they've seen a family physician before about their mental health, whether they've ever had depression or anxiety, the association still persists and is quite strong," he said.

For cannabis users who have not experienced psychosis, Myran said the likelihood of schizophrenia in the next three years is 2 percent. But, due to this population segment making up a majority of users, they also represent the majority of schizophrenia cases related to cannabis use, he said.

Myran also discussed the impacts of cannabis use during pregnancy and the statistics surrounding it in relation to legalization. He added that cannabis use disorder is not always identified as such, and there may be undetected cases in which the pregnant person was using cannabis.

Upon examining pregnancies in Ontario, Myran's research group found an 82 percent increase in pregnancies afflicted with cannabis use disorder approximately within the first two and a half years following cannabis legalization. Though, he said a total of 540 pregnancies were affected by cannabis use disorder, making it a relatively rare phenomenon.

Myran noted that though cannabis legalization can be beneficial for criminal justice, its commercialization into products, such as cannabis-infused candies, contributes to poisoning in young children.

"We see that … when the edibles come to market, we see that Ontario, Alberta (and) British Columbia, who allow the sale of legal edibles, experience a further three times increase in rates of poisoning hospitalization," Myran said. "And that Quebec, who did not allow edibles to come to market, or allowed a small amount of dried cannabis figs to come to market, sees no significant change."