- Canadian researchers say the legal age to use marijuana recreationally should be 19.
- They say age 19 is a balance between preventing drug addiction and keeping young adults from misusing other types of drugs.
- Experts say the study has some valid conclusions, but there are concerns about the impact of cannabis on brain development before age 25.
In the United States, you have to be 21 years old to buy alcohol.
But Canadian researchers say that the legal age to use marijuana recreationally should be 19 — more or less the same as the legal drinking age in Canada.
“Contrary to the Canadian federal government’s recommendation of 18 and the medical community’s support for 21 or 25, 19 is the optimal minimum legal age for non-medical cannabis use,” Hai Van Nguyen, PhD, an associate professor at the Memorial University of Newfoundland in Canada and a lead study author, said in a press statement. “Keeping the legal age below 21 may strike a balance between potential increases in underground markets and illegal use, and avoiding the adverse outcomes associated with starting to use cannabis at an earlier age.”
In Canada, provinces have set the minimum legal use age at 18 or 19, generally tracking the legal age for alcohol use.
Debate continues, however, on whether the marijuana use age should be increased to 21 in Canada.
The study, published in the journal BMC Public Health, includes recommendations based on a review of research into first use of marijuana relative to later tobacco use as well as educational attainment, and physical and mental health measures.
Researchers found, for example, that those who first used cannabis at age 18 were more likely to smoke cigarettes later in life than those who first used cannabis at age 19 or 20.
Initiation of marijuana use at ages 19 or higher also was associated with higher educational completion rates, better general health, and better mental health.
“The lower level of completed education reported in those who first used cannabis at an earlier age may reflect poor neurological development or a higher dropout rate from further education,” said Nguyen. “It is also possible that those who initiate cannabis use early may use it as a gateway for further illicit drug use, resulting in poorer health in later life, which may explain the poor general or mental health scores recorded in the study.”
Outcomes were not improved with cannabis initiation at ages 20 or above, however.
“We found that most later life outcomes are better for individuals starting cannabis at age 19 than those starting it at age 18 but not worse than those starting cannabis between age 20 and 25,” Nguyen and Shweta Mital, a PhD student at Memorial University and a study co-author, wrote in a commentary accompanying the study. “These results imply that age 19 is the optimal (minimum legal age) for cannabis use.”
Age 19 “is high enough to address concerns over potential adverse outcomes associated with using cannabis at young age, while low enough to discourage the illegal market for the underage,” wrote Nguyen and Mital.
Susan Weiss, PhD, director of the division of extramural research at the National Institute on Drug Abuse, told Healthline that the Canadian study is an “interesting first step” in developing minimum-use policies based on research.
Weiss said that in addition to the indicators examined in this study, it also will be important to look at the relationship among age, marijuana use, and alcohol use, psychosis, and suicide.
Weiss added that most past drug studies have focused on use among elementary and high school students, not young adults.
“We don’t have as much research on what happens in that [older] time frame,” she said. “We do know that the brain is still developing until age 25.”
“Policy making is difficult because it’s not only public health based,” added Weiss. “If you push everyone into the black market, you’re not necessarily gaining anything.”
Betty Aldworth, executive director of Students for Sensible Drug Policy, told Healthline that the study recommendations were generally on target.
“Prior research on illicit markets and age-restricted substances predicts that restricting purchase to those 18 or 21 and older while accurately educating people at all ages about the impacts of cannabis use — both positive and negative — will lead to the best outcomes,” she said.
However, Caleb Chen, editor of the cannabis review site The Highest Critic, told Healthline that the Canadian recommendations may not be easily adoptable in the United States.
“Because of the federal level classification of cannabis as a schedule I drug, there hasn’t been enough research to know if 19 is too old or too young to be the legal minimum age for non-medical marijuana use,” Chen said. “It’s important to note that for most of Canada, except Quebec, 19 is the minimum age for recreational use, so we may see research on the effects of that in the coming years.”
“Another result of the still-extant federal ban on marijuana is that individual states could lower the minimum age for non-medical use. However, that is an uphill battle that I don’t think we’ll see,” added Chen. “It’s much easier for the general public to accept 21 as the legal minimum age because that’s where alcohol is set at.”
Linda Richter, PhD, director of policy research and analysis at the Center on Addiction, said her center’s
“The argument to reduce the legal age of sale of marijuana to 19 is misguided in much the same way similar calls to reduce the legal age of sale of alcohol or tobacco have been,” Richter told Healthline. “Although it is not realistic in our current legal, political and cultural climate, scientific research largely suggests that the optimal age of legalization to protect the public health would be 25 or later, not 19 or younger.”