5 years of legal cannabis: fewer charges, many hospitalizations and more than a few questions

When Canada legalized the use of cannabis in October 2018 after decades of prohibition, the goals were to improve safety and public health as well as to reduce access by youth, crime and the illegal market.

Five years later, public health experts say legalization hasn’t created any health benefits — but it has been linked to some serious concerns.

Tuesday’s issue of the Canadian Medical Association Journal includes a commentary taking stock on what’s happened with the legalization of non-medical cannabis. The paper doesn’t examine a greater uptake of medical cannabis, which has been regulated by the government since 2001.

More than a quarter of Canadian adults — 27 per cent — say they use cannabis, up from 22 per cent in 2017, said author Benedikt Fischer, an adjunct professor at the Centre for Applied Research in Mental Health & Addiction at Simon Fraser University in Vancouver.

“Cannabis has been a widely available, normalized and even promoted product,” Fischer said.

Benefits

Though the CMAJ commenters did not cite any direct health benefits from legalization, the paper notes the important social justice benefits from substantial reductions in criminal arrests and charges, along with the associated stigma.

Two-thirds of active cannabis users now get their cannabis from legal sources, according to the paper. 

In Quebec, the minimum age to use cannabis was upped to 21. The province also introduced other restrictions such as not allowing edibles that would appeal to young people, like gummies, candies and chocolate.

“I think there’s some positive protective effects from that,” Fischer said.

WATCH | The science of getting high:

Harms

After legalization, there was a large uptick in cannabis poisonings among young children in provinces where edibles were legal. These events were rare but highlighted the importance of child safety packaging. 

But the increased availability of cannabis also led to other health concerns bringing people to hospital, says another new paper that studied the cannabis-attributable hospitalizations in four provinces, both before and after legalization.

The study’s authors combed through hospitalization data on nearly seven million people aged 15 and up in Ontario, Quebec, Alberta and British Columbia. Their findings were published Thursday in JAMA Network Open.

There were 105,000 hospitalizations for cannabis over a seven-year period from January 2015 through March 2021, the report says. One-third were among people aged 15 to 24, while nearly 70,000, or 66 per cent, were among males.

The study focused on three time periods: pre-legalization (January 2015 to September 2018); post-legalization with product and store restrictions (October 2018 to February 2020); and post-legalization with commercialization, resulting in more stores and product access (March 2020 to March 2021). The latter period overlapped with the COVID-19 pandemic.

During the early years of legalization, with tightly controlled products and limited store access, the rate of hospitalizations didn’t notably change. However, data suggests that the commercial period was accompanied by an increase in cannabis hospitalizations, particularly among people aged 25 years and older, the study’s authors said.

Going from a couple of cannabis stores in a city to hundreds increased availability, which can lead to overuse problems, said lead author Daniel Myran, a family physician with the Ottawa Hospital Research Institute.

From his work in public health and as a researcher, Myran said people, mostly young men, commonly show up in emergency departments after using cannabis because they’re experiencing withdrawal or are intoxicated but not displaying cannabis-related psychosis. Myran said they are at risk — slight but there — of developing a serious mental disorder. 

“They have almost a two per cent risk of developing schizophrenia within three years,” said Myran. In comparison to the general population, the risk is well below one per cent. 

Cannabis-induced psychosis had the largest relative increase for hospitalizations, the study said.

Both genes and environmental factors predispose some people to using cannabis and to developing schizophrenia. Myron said more research is needed to understand the risk, calling it an area that is under-discussed.

The increasing potency of cannabis sold after commercialization matters, said Romina Mizrahi, a psychiatrist and professor at McGill University in Montreal. She wasn’t involved in the research.

If legalization is done correctly, users would receive important information on how much psychoactive  tetrahydrocannabinol (THC) they’re ingesting.

“When we talk to patients, we explain what this means,” Mizrahi said. “We ask them to take a look at what they buy.”

Using cannabis can also be risky during pregnancy. Myran pointed to a previous study on people treated for cannabis-use disorder in Ontario. The results suggested a doubling in the rate of poor outcomes in newborns among the less than one per cent of pregnancy visits to hospital for cannabis use, compared with cannabis-free pregnancies.

Mixed or uncertain

The CMAJ paper noted that impaired driving related to cannabis appeared to be the same or slightly down from pre-legalization levels. In B.C., however, the proportion of drivers admitted to hospital after vehicle collisions who tested positive for THC increased after legalization, Fischer and his team said.

Impaired driving numbers could be lower as a result people not venturing out of their homes during the COVID pandemic.

Myran calls the effects of legalization an unfinished story.

Doctors and scientists want better tracking on the demand for treatment for cannabis use disorders and how people may be substituting other substances to get high.

Said Myran: “Our data, while not conclusive, is hinting that as the market expands, when you see greater levels of market maturity, new products, that you do see these increases in cannabis harms.”