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How Cannabis Use Affects Mental Health

March 22, 2024 from DATAC

In recent months, researchers from the Ottawa Hospital Research Institute, led by Dr. Daniel Myran, have published several studies examining the association between cannabis use and mental health disorders. These studies are particularly significant in the context of cannabis legalization in Canada in 2018, as they provide critical insights into the potential health concerns associated with cannabis use.

Cannabis Use and Anxiety Disorders

The first study, published in the Lancet, explored the connection between cannabis use and anxiety disorders. The research involved analyzing health records of over 12 million individuals aged 10 to 105 years across Ontario from 2008 to 2019. The study specifically looked at individuals with no prior history of anxiety disorders.

The striking findings showed that 27.5% of individuals who visited a hospital for cannabis use were diagnosed with an anxiety disorder within three years of their hospital visit, compared to only 5.6% of the general population. Moreover, those who visited a hospital for cannabis use were also found to visit a hospital for an anxiety disorder within three years at a rate of 1.2%, in contrast to the 0.6% in the general population.

“ED visits for cannabis use were associated with an increased risk of having an incident healthcare visit for an anxiety disorder, particularly in young males. These findings have important clinical and policy implications given the increasing use of cannabis over time and trend towards legalization of cannabis,” the study authors concluded.

Cannabis-Induced Psychosis and Schizophrenia Spectrum Disorders

Two additional studies published in JAMA Psychiatry and Molecular Psychiatry found a dramatic increase in emergency room visits for cannabis-induced psychosis in Ontario, rising by 220% from 400 to about 1,400 people between 2014 and 2021. The findings also suggest that emergency room visits for substance use are associated with an increased risk of developing schizophrenia spectrum disorders.

Dr. Myran highlighted the public’s lack of awareness regarding the connection between cannabis use and the potential risk of chronic psychotic disorders. “For men aged 14 to 24, the risk of developing schizophrenia rises to over 40% within three years of showing up in an ER for cannabis-induced psychosis,” he noted in an interview with CBC News.

Concerns Over High Cannabis Content

Researchers also expressed concerns about the high cannabis content in commercially available products today. Dr. Philip Tibbo, a professor and director of research in the department of psychiatry at Dalhousie University in Halifax, emphasized the significant difference in cannabis potency compared to the past. “It’s been around for centuries. True enough. But the product that we’re using today that’s available to our youth and young adults into the population today is completely different than even what it was 10, 15 years ago,” he explained in an interview with CBC News.

Implications for Policy and Public Health

The findings from these studies underscore the need for increased awareness and education regarding the potential mental health risks associated with cannabis use. As cannabis use becomes more widespread, particularly among young people, understanding these risks is crucial for both clinicians and policymakers to mitigate potential adverse health outcomes.


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