Updated: Oct 24
The commercialization of cannabis that followed its legalization for nonmedical use was associated with an increase in hospitalizations for cannabis-related health problems, including cannabis-induced psychosis, according to new research.
In a repeated cross-sectional analysis that included some 26.9 million individuals, researchers found that the rate of hospitalizations due to cannabis increased 1.62 times between 2015 and 2021.
The rate of hospitalizations increased most precipitously after commercialization, including a 40% increase in hospitalizations for cannabis-induced psychosis.
"There were harms from a public health standpoint, regarding criminal convictions related to cannabis," study author Daniel T. Myran, MD, MPH, a family and public health physician at the University of Ottawa, Ottawa, Ontario, Canada, and an investigator at the Bruyère Research Institute in Ottawa, Ontario, Canada, told Medscape Medical News. "You can have important public health gains from legalization. I think the caution in our study warns that there is a big difference between legalizing or decriminalizing cannabis and commercializing it."
Decline With Legalization
Canada has a universal healthcare system, and the researchers accessed health administrative databases that recorded all acute hospitalizations for patients aged 15 to 105 years in the four most populous provinces: Ontario, Quebec, Alberta, and British Columbia. They compared changes in rates of hospitalizations due to cannabis over the following three time periods: prelegalization (January 2015 to September 2018), legalization with product and store restrictions (October 2018 to February 2020), and commercialization (March 2020 to March 2021).
There were 105,203 hospitalizations due to cannabis during the study period. Most (65.8%) were in males, and one third were in adolescents and young adults aged 15 to 24 years. The age- and sex-standardized rate of hospitalizations due to cannabis increased 1.62 times: from 3.99 per 100,000 individuals in January 2015 to 6.46 per 100,000 individuals in March 2021.
The largest relative increase in hospitalizations was for cannabis-induced psychosis, which rose 40% during the commercialization period, compared with the prelegalization period (rate ratio, 1.40).
The period of legalization with restrictions was associated with a gradual monthly decrease of −0.06 in hospitalizations due to cannabis per 100,000 individuals
During the commercialization period, which coincided with the COVID-19 pandemic, there was an immediate increase of 0.83 hospitalizations due to cannabis per 100,000 individuals.
'Legalization, Not Commercialization'
Legalizing cannabis removes an important reason for incarceration, said Myran. "That is an important public health gain. There’s very compelling data that making cannabis illegal ended up giving a lot of young people criminal records, and in Canada, it’s disproportionately in Black and indigenous youth. You get a criminal record, and it has major social harms."
Before cannabis was legalized in Canada, it became easier to obtain. Gray market stores selling cannabis were no longer being closed by the police. In the lead-up to legalization, cannabis use increased. But once legalization with restrictions was instituted, hospitalizations for cannabis use declined, said Myran.
"Legalization in Canada has taken a graduated rollout, so you have an initial legalization with restrictions, where the government would only allow the sale of dried cannabis flower, there were almost no stores, and you actually see these rates decline. But later on, when the market matures and you have a vast amount of stores, new products like vape pens and edibles and concentrates and cannabis-infused beverages, and which happens to overlap with the COVID-19 pandemic, you see a jump in cannabis hospitalizations," he said.
Cannabis use can be very harmful for some individuals. It is well known that cannabis use in adolescents and young adults is associated with the development of psychosis, said Myran.
"There are individuals who are predisposed to develop psychosis, and cannabis seems to bring on psychotic episodes in those who are vulnerable. In one study, 26% of people who presented to the emergency department with an episode of cannabis-induced psychosis went on to develop schizophrenia within the next 3 years," he said.
We need legalization, not commercialization, Myran said.
Promoting Cannabis Misuse?
Commenting on the findings for Medscape, Simon Sherry, PhD, professor of psychology at Dalhousie University in Halifax, Nova Scotia, Canada, said, "This is important and meaningful research that is helping us understand that our government is playing an active role in creating a culture of cannabis misuse."
Increased commercialization is increasing the availability of cannabis, hence problems with abuse and overuse will occur, he added. Sherry did not participate in the research.
"We know from the alcohol literature, the tobacco literature, and increasingly from the cannabis literature that with the increase of the physical availability of cannabis outlets, you also increase potential for abuse of cannabis," he said.
While claims that sales of cannabis products provide a source of revenue for governments may be true, the main source of that revenue is the regular user, Sherry said.
"The dirty secret in the legalization and commercialization of cannabis is that most of the revenue comes from frequent or addicted customers. Someone who buys 1 gram and uses it recreationally in a month is not a good customer. The good customers are frequent and addicted individuals who are going to smoke 5 grams of cannabis a day."
Commercialization results in more direct appeals to addiction-prone people, Sherry added. "For instance, in Nova Scotia, we promote cannabis as a way to relax and enhance your experience. If you are addiction-prone, that messaging, and the increased physical availability of cannabis with commercialization, means that we are going to see more cannabis problems. So, if you add more cannabis outlets, as you heavily commercialize cannabis products, you add more cannabis problems to our society."
Cannabis is not a benign substance, Sherry emphasized. Increasing awareness of the associated harms, as has occurred with tobacco, would be a better way of marketing cannabis, he suggested.
"Rather than the current relaxed and permissive attitude, we need to switch to one of grudging tolerance, recognizing that cannabis is going to be part of our landscape, that some people are going to use it and some are going to misuse it, and that we need to discourage the consumption of cannabis as a public health problem," said Sherry.
The study was supported by a grant from the Canadian Centre on Substance Use and Addiction and fellowships from the Canadian Institutes of Health Research and the University of Ottawa Department of Family Medicine. Myran reported grants from Canadian Institutes of Health Research during the conduct of the study. Sherry reported no relevant financial relationships.