Legalizing Marijuana Led To An Increase In Use—But A Decrease In Problematic Misuse, American Medical Association Study Shows

New research published by the American Medical Association (AMA) finds that while the frequency of marijuana use among adults in Canada increased slightly in the years following nationwide legalization, problematic misuse of cannabis in fact saw modest decreases.

The report, which was published on Wednesday in JAMA Network Open, looked at data from 1,428 adults aged 18 to 65, who completed assessments roughly every six months between September 2018 and October 2023.

A primary goal of the study, which was partially funded by the federal agency the Canadian Institutes of Health Research, was to examine how consumption patterns changed following the country’s legalization of adult-use marijuana, sales of which began in October 2018. Researchers also wanted to understand whether use patterns changed based on how frequently people used cannabis prior to legalization as well as how users’ product preferences changed.

Frequency of marijuana use overall increased slightly but significantly over the five-year period. Among all participants, the mean proportion of days using cannabis increased by 0.35 percent per year, or 1.75 percent over the five-year study period.

People who used cannabis most frequently before legalization saw the largest declines in use. People who consumed marijuana on a daily basis prior to legalization decreased their use frequency more than those who’d used marijuana on a weekly basis.

Those who used marijuana once a month or less before legalization, meanwhile, reported slight increases in use.

“Cannabis use frequency increased significantly overall while misuse decreased.”

As for misuse, analysis using the so-called Cannabis Use Disorder Identification Test – Revised (CUDIT-R) showed a significant decrease in cannabis misuse overall, authors wrote, especially during the early months of the COVID-19 pandemic, from April to October 2020.

People who used marijuana monthly or less than monthly before legalization saw their CUDIT-R scores drop significantly, while those who’d never used marijuana saw a slight increase—suggesting that at least some people did start using after legalization and then develop problematic habits.

Notably, people who were using marijuana weekly prior to legalization saw their average CUDIT-R scores fall “from above to below the validated CUDIT-R cutoff score of 6 indicating problem cannabis misuse,” the study says. That suggests a healthier post-legalization relationship with marijuana among occasional users.

One explanation for that trend could be the age of consumers. “The apparent discrepancy between increasing cannabis use and decreasing cannabis misuse may have been driven by younger cannabis users,” the report says, “who typically transition from problematic to nonproblematic use as they age.”

As for how use patterns changed based on frequency of use prior to legalization, authors wrote that “it is also possible that regression to the mean explains part of the interaction findings.”

“Fundamentally, however, these results do not suggest increased adverse outcomes for adults who were actively using cannabis before legalization,” they said.

Regarding product preferences, the study period overall saw statistically significant decreases in the use of flower, cannabis concentrates, oil, tinctures and topicals. Increases, meanwhile, were observed in the use of edibles, beverages and vape cartridges.

“The most pronounced increase was in use of cannabis oil cartridges or disposable vape pens,” the report says, “with a 3.39% annual increase in prevalence among active cannabis users (from 18.4% prelegalization to 33.0% at 5 years postlegalization).”

Authors wrote that while there’s a need for further study, results suggest both positive and negative consequences of legalization. On the negative side is the observed increase in frequency of use. On the positive side, meanwhile, are lower scores for marijuana misuse as well as an apparent “transition from combustible to noncombustible cannabis products,” which are understood to carry lower health risks.

“From a public health standpoint, these results are mixed,” the report says, “as increased use might be considered harmful, while decreased misuse is a positive outcome.”

Additionally, while the results were statistically significant, the research team noted that “for both outcomes…it is debatable whether these changes were clinically significant.”

That’s especially true in the case of misuse CUDIT-R scores, “which decreased by only 0.4 points on a scale of 32 over 5 years,” the study says.

Governments and public health experts have been working to track consumer behavior as laws around marijuana continue to change. In the U.S., a Centers for Disease Control and Prevention (CDC) report recently broke down federal data on cannabis use among thousands of U.S. adults, finding that while smoking marijuana remains the most common way to consume it, methods such as eating, vaping and dabbing are growing in popularity.

Overall in 2022, 15.3 percent of adults reported current marijuana use, while 7.9 percent reported daily use. Among users, most (79.4 percent) reported smoking, followed by eating (41.6 percent), vaping (30.3 percent) and dabbing (14.6 percent).

About half of all adults who used marijuana (46.7 percent) reported multiple methods of use—most typically smoking and eating or smoking and vaping.

Rates of both vaping and dabbing—as well as cannabis use in general—were higher in young adults than the general adult population.

An earlier analysis from CDC found that rates of current and lifetime cannabis use among high school students have continued to drop amid the legalization movement.

Another recent federal report, published by the Substance Abuse and Mental Health Services Administration (SAMHSA), found that consumption among minors—defined as people 12 to 20 years of age—had fallen slightly in the past year. Despite methodological changes that make comparisons over time difficult, it also suggests that youth use has fallen significantly in the past decade.

A separate poll recently found that that more Americans smoke marijuana on a daily basis than drink alcohol every day—and that alcohol drinkers are more likely to say they would benefit from limiting their use than cannabis consumers are.

U.S. adults who drink alcohol are nearly three times as likely to say they’d be better off reducing their intake of the drug compared to marijuana consumers who said they’d benefit from using their preferred substance less often, the survey found. Further, it found that while lifetime and monthly alcohol drinking among adults was far more common than cannabis use, daily marijuana consumption was slightly more popular than daily drinking.

An earlier report published in the Journal of Studies on Alcohol and Drugs that found that secondhand harm caused by marijuana use is far less prevalent than that of alcohol, with respondents reporting secondhand harm from drinking at nearly six times the rate they did for cannabis.

Yet another 2022 study from Michigan State University researchers, published in the journal PLOS One, found that “cannabis retail sales might be followed by the increased occurrence of cannabis onsets for older adults” in legal states, “but not for underage persons who cannot buy cannabis products in a retail outlet.”

The trends were observed despite adult use of marijuana and certain psychedelics reaching “historic highs” in 2022, according to separate data.

Marijuana Companies Donated At Least $1 Million To Trump’s Inauguration, New Federal Records Show