The Impact of Marijuana Legalization on Problematic Use and Public Health Outcomes: Evidence from the United States and Canada
The legalization of marijuana in the United States and Canada has not led to a surge in harmful cannabis use or negative health and social outcomes, according to recent studies. In fact, evidence from both countries has shown no increase in rates of problematic cannabis use after states legalized marijuana, especially among youth. The risk of problematic cannabis use also does not appear to have increased in the two years following cannabis legalization in Canada.
Separate analyses examining the impacts of Canada’s cannabis legalization law found no rise in cannabis-induced psychosis, car crashes, other injuries, or emergency room visits due to intoxication. Studies also found a growing share of users obtain cannabis legally and stable use rates among young adults ages 18-25.[0] However, the existence of a link between marijuana use and schizophrenia has been known for decades and a new study not only reaffirms the connection but also shows the problem’s growing severity, especially among young men.
The study, which was conducted by researchers at the universities of Waterloo and Toronto, assessed rates of “high-risk” cannabis use among people aged 16-65 in the years after legalization and found no evidence of a change in the proportion of those whose cannabis use would be classified as high risk. To determine risk levels, the respondents were asked about the frequency of their cannabis use and the symptoms of their cannabis use disorder.[0] Weekly use with some signs of dependence was considered moderate use, whereas daily use with a cannabis use disorder was classified as high-risk use. In 2018, 2019, and 2020, groups of individuals with different age ranges were evaluated by researchers to identify those who had issues with cannabis consumption. The percentage of subjects rated as low risk for problematic behavior was 89.1 in 2018, which decreased slightly to 88 percent in 2020.[1]
The new study also notes that in terms of non-problematic use, the number of people who had used cannabis once in the last month, last three months, or last twelve months, did increase.[1] Did this also suggest a rise in problematic usage?[1] Researchers call for continued monitoring to understand the public health impacts of legalization over the longer term.
Overall, the findings suggest that Canada has not seen a major rise in cannabis misuse and addiction since the country legalized recreational pot. However, marginalized groups remain at higher risk, and there is a general consensus that marijuana (aka cannabis) is a relatively harmless drug.[2] With 22 states and Washington, D.C. allowing for the legal use and sale of marijuana, it continues to be legalized across the U.S.[2]
Nevertheless, the link between heavy cannabis use and schizophrenia has been a concern for decades. The new study shows the problem’s growing severity, especially among young men, and blames the “increasing prevalence” of the problem on the “higher potency of cannabis” typically used today compared to typical street marijuana half a century ago. However, researchers do not yet know if the marijuana use in these cases causes schizophrenia or if a predisposition is triggered by marijuana use or if some other causal mechanism might be at work.
In conclusion, while the legalization of marijuana in the U.S. and Canada has not led to a surge in harmful cannabis use, the link between heavy cannabis use and schizophrenia remains a concern. Continued monitoring and research is needed to fully understand the public health impacts of legalization over the longer term and to address the risks of problematic cannabis use, particularly among marginalized groups.
0. “No significant increase in high-risk use of cannabis after legalization: study” Mugglehead, 15 May. 2023, https://mugglehead.com/no-significant-increase-in-high-risk-use-of-cannabis-after-legalization-study/
1. “New cannabis study shows no significant change in rates of use-disorder post-legalization” StratCann, 15 May. 2023, https://stratcann.com/news/new-cannabis-study-shows-no-significant-change-in-rates-of-use-disorder-post-legalization/
2. “Casual marijuana use in teens isn’t harmless. Here’s why experts say parents should be ‘very concerned.’” Yahoo Life, 17 May. 2023, https://www.yahoo.com/lifestyle/marijuana-use-teens-depression-195633466.html
