Fewer young people will smoke pot when it's made legal next year because access to marijuana plants will be restricted, the federal Liberal government argues.
Recent U.S. federal drug use statistics — which show a meaningful decline in the number of teenage Coloradans using cannabis in recent years — lend some support to the government's theory.
Canadian experts say it's too early to tell whether those statistics represent conclusive evidence that legalization results in reduced youth cannabis use.
The statistics come from the federal Substance Abuse and Mental Health Services Administration's national survey on drug use and health, which measures two-year cycles of substance use among different age groups in all 50 U.S. states and the District of Columbia.
From 2014-15 to 2015-16, reported past-month marijuana use by 12- to 17-year-old Coloradans fell to 9.08 per cent from 11.13 per cent, a significant decline. Colorado is considered important by cannabis policy makers because it was one of the first U.S. jurisdictions to legalize marijuana for recreational use.
The statistics don't explain the cause of the drop in youth cannabis use in the state, but public health experts have some theories.
"I'm not overly surprised that there's a decrease in use because there's an increased awareness of cannabis amongst parents and guardians and other adults," says Ian Culbert, executive director of the Canadian Public Health Association.Advertisement
"It is a positive upside of legalization, that we're talking about use and why people use and how you use," says Culbert. "When it's illegal, we don't necessarily have those conversations, we just say, 'It's illegal, it's bad, don't use it, end of conversation.'"
'Too soon to make a strong conclusion'
Dr. Christina Grant, a physician and associate professor of pediatrics at McMaster University who has studied youth cannabis use, points out that even though past-month use by Colorado teens declined in a statistically significant way, the slight decline in past-year rates of use among those teens is not considered statistically meaningful.
"Is it that we're seeing less frequent use in youth? We can't see less (use) overall based on the (year-over-year statistics)," says Grant.
"It's too soon to make a strong conclusion with just one year (of) data. When we get next year's and the following year's, we're going to have a little bit more, because if we see a significant decrease every single year, then I think that that's going to be more helpful."
Grant isn't just concerned about cannabis use among youth aged 12 to 17, though. The survey data also show a statistically significant increase in past-month cannabis use rates among 18- to 25-year-olds in the District of Columbia, where cannabis is also legal.
"While it is encouraging to see from this one study that rates were significantly lower in those under 18, obviously that's good news," says Grant. "But the other concern is there, that actually rates went up significantly in that 18 to 25 (age group in Washington, D.C.), because we know that brain changes are continuing to happen in that age group."
The U.S. data are "interesting," says Rebecca Jesseman, a senior policy adviser with the Canadian Centre on Substance Use and Addiction, "but the data was collected in such a way that we can't call it conclusive."
Other U.S. drug-use surveys have shown "slightly different results" in terms of youth use rates, says Jesseman, citing a recent University of Michigan survey that showed increased rates of past-year marijuana use by U.S. teens in Grades 8, 10 and 12.
"When we're looking at these different survey data without having a perfect source, which is certainly very challenging to come by, what we're looking for is consistency of results, so what we'd refer to as triangulation," she explains.
"Are there consistent results across different sources, even though perhaps different methodologies have been used? That's what would really give us confidence in speaking to results. I would say that we're seeing a fair amount of variation still, but what we're not seeing is any huge red flag causes for concern — or any huge causes for celebration."
The lesson Canadian policy makers can draw from all these U.S. statistics, believes Jesseman, is the importance of collecting solid data about how Canadians use cannabis on an ongoing basis.
"Consistent data collection can help us to identify emerging problems, because we really don't know what the regulated market is going to look like," she says.
'Crucial importance' of collecting good cannabis data
Collecting high-quality data on cannabis use will be especially important "because we're going to have 13 different approaches to cannabis legalization in Canada," says Nazlee Maghsoudi, a knowledge translation manager at the International Centre for Science in Drug Policy.
"Whether that's related to youth cannabis use, other youth drug use like alcohol, or just other outcomes that we think are really important, there's this really crucial importance of making sure that we're collecting good data, that we have baseline data so that we can... at least be able to point to some differences that we're seeing within that new policy context."
Maghsoudi sees the decline in youth cannabis use rates in Colorado as "a clear public health win," which she says could be the result of improved youth drug education programs in the state. The state's initial anti-marijuana campaign, called "Don't Be a Lab Rat," aimed to convince teens that using cannabis was akin to subjecting themselves to a potentially dangerous experiment. That campaign gave way to more education-focused campaigns such as "Good to Know" and "What's Next?"
That kind of willingness to rethink public health approaches to cannabis, says Maghsoudi, will also be important in Canada.
"There's lots of evidence that the education tactics that have been used in the past have not been effective in reducing youth (use); in some case they have the opposite effect: they pique interest in youth." -Nazlee Maghsoudi
"We've been thinking with the prohibition mindset for so long that it's not necessarily the easiest thing in the world to switch over to the approach that is more appropriate within the context of legalization and regulation," she says.
"We know that fear-mongering doesn't work. There's lots of evidence that the education tactics that have been used in the past have not been effective in reducing youth (use); in some case they have the opposite effect: they pique interest in youth," Maghsoudi says.
Strong, easy-to-compare cannabis-use data from across Canada, she says, will let policy makers "take those best practices and lessons learned from other provinces and apply them in places where they'd accomplish something really wonderful."