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Legalization Is Not Associated With Spikes In Cannabis-Related Psychosis

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One of the most common mainstream media hit jobs in modern times involves opponents implying that cannabis reform alone has led to a spike in incidents of cannabis-related psychosis among consumers and patients.

Cannabis legalization, by every reasonable measure, has been an overwhelming success in jurisdictions that have allowed it, including in Canada where cannabis was first legalized for adult use in late 2018.

Researchers in Canada examined data involving incidents of cannabis-related psychosis and determined that legalization is not associated with spikes in such incidents. Below is more information about it via a news release from NORML:

London, Canada: The legalization of the Canadian marijuana market is not associated with increases in rates of cannabis-related psychosis, according to data published in the International Journal of Drug Policy.

A team of Canadian researchers examined regional changes in health services use and incidences of psychotic disorders during the months immediately following legalization. (Canada legalized marijuana possession and retail sales in October 2018.)

They reported, “We did not find evidence of increases in health service use or incident cases of psychotic disorders over the short-term (17 month) period following cannabis legalization.” They cautioned, however, that “a longer post-legalization observation period … is needed to fully understand the population-level impacts of non-medical cannabis legalization.”

The finding is consistent with the conclusions of a 2022 study published in the Canadian Journal of Psychiatry. Its authors similarly determined that the “implementation of Canada’s cannabis legalization framework was not associated with evidence of significant changes in cannabis-induced psychosis or schizophrenia ED [emergency department] presentations.”

In the United States, state-level marijuana legalization laws have not been associated with a statistically significant increase in psychosis-related health outcomes. Specifically, a 2022 paper published in the Journal of the American Medical Association (JAMA) Network Open found no association between the adoption of marijuana legalization and overall rates of psychosis-related diagnoses or prescribed antipsychotics.

Although the use of cannabis and other controlled substances tends to be more common among those with psychotic illnesses, studies indicate that lifetime incidences of marijuana-induced psychosis are relatively rare among those who do not have a prior psychiatric diagnosis. According to one recently published study, fewer than one-half of one percent of cannabis consumers had ever reported experiencing psychotic symptoms requiring medical intervention – a percentage that is lower than the rate associated with alcohol.
Full text of the study, “Impact of non-medical cannabis legalization with market restrictions on health service use and incident cases of psychotic disorder in Ontario, Canada,” appears in the International Journal of Drug Policy. Additional information is available from NORML’s op-ed‘Concerns surrounding cannabis and mental health must be placed in context, not sensationalized.