Will cannabis consumption increase after legalization? New research produces first results

The legalization of cannabis is controversial for several reasons. One of the arguments against legalization is that drug use will increase. There are hardly any long-term studies examining this question. But now a study from Canada – where cannabis has been fully legal for adults since October 2018 – has brought some clarity to the matter.

In Canada, opponents of legalizing recreational use of cannabis also feared that easier availability would cause consumption of the drug to skyrocket, especially among young adults. This is the age group that already has the largest share of cannabis users and is most affected by the associated problems.

In fact, early numbers seemed to confirm fears: According to the Canadian Statistics Authority, about 646,000 people in Canada said they used cannabis for the first time in the first quarter of 2019 – almost twice as many as in the first quarter of 2018. i.e. before legalization. The largest group, of course, consisted of men between the ages of 45 and 64, and not young adults. Moreover, not all of them were truly new users, as some were former cannabis users “who tried again after legalization,” as the authority explained.

Meanwhile, the new research from McMaster University in Hamilton, Ontario, published in JAMA Network Open, found that both cannabis use and associated problems have declined since legalization. However, the basis of the sample did not consist of starters, but of high-risk young adults, that is, people aged 19.5 to 23 years who stated at the beginning of the study that they regularly drink a lot of alcohol (so-called binge drinking), and the majority of them used cannabis (65% of participants reported using cannabis in the past month).

This population group was deliberately chosen because scientists assume that an increase in cannabis use will most likely be observed in this risk group as a result of legalization. The total of 619 study participants from Ontario were surveyed about their consumer behavior every four months for three years – from February 2017 to February 2020. Since monitoring began before legalization in October 2018, the scientists were able to observe any effects.

The study found that both cannabis consumption and its negative consequences, such as a lack of energy or neglect of obligations, decreased significantly among subjects overall. It was found that those who had regularly consumed cannabis before legalization reported the largest declines after legalization, both in consumption and in the negative consequences associated with it. In contrast, those who did not use cannabis before legalization experienced a slight increase in use afterwards, but no increase in cannabis-related negative outcomes.

However, the decline in cannabis use among the heaviest users cannot simply be attributed to legalization. It’s a normal process: many cannabis users reduce or stop using cannabis as they get older. This phenomenon is called ‘aging out’. The fact that there was a slight increase in the number of people who had not used cannabis before legalization could indicate that legalization caused a slight increase.

“Our study is a great example of why ongoing monitoring of substance use behavior is so important for evidence-based decision making,” lead author Amanda Doggett, a postdoctoral researcher at the Peter Boris Center for Addictions Research at McMaster University, explained in a statement from the university. “We were able to measure cannabis use and experiences of cannabis-related consequences in the same individuals before and after legalization and observe trends consistent with the expected exit pattern.”

However, the study cannot answer the question of whether the results would have been different without the legalization of cannabis. This would require observation of a control group of similar young adults who do not live in a region where cannabis has been legalized for recreational use. This should be done in further studies; Doggett is therefore working with researchers from the US.

James MacKillop, director of the Center for Medical Cannabis Research and professor in the Department of Psychiatry and Behavioral Neuroscience at McMaster University, points out that the study participants, who were classified as high-risk, acted as a kind of “canary in the cabbage.” mine.” “If you assume that legalization will have a widespread impact on young adults, we should have seen that in this risk group,” he says.

According to the study authors, the study results close a crucial knowledge gap and provide a foundation for future research. The scientists also hope the findings will help policymakers understand the broader implications of cannabis legalization. At the same time, however, they emphasize that caution is required when interpreting the results.

MacKillop warns:

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