Sean Savoie first smoked marijuana around the age of 14 when, behind a gas station, a friend handed him a pop can fashioned into a bong. He doesn’t remember if he got high or even enjoyed the experience, but he did start smoking two or three times a week. Marijuana became a way for Savoie to create an identity for himself during those tumultuous high school years, and a way to make friends. His parents disapproved and urged him to quit, but he never abandoned the habit for long. Eventually, his parents stopped trying, contenting themselves with the fact that at least their son wasn’t using harder drugs. “That kind of told me that it’s okay,” says Savoie, who lives in Winnipeg. “So I started using every day.”

By the time he was in university, Savoie was smoking multiple times a day. He’d spark up as soon as he rolled out of bed, as well as before hanging out with friends, before a video game session, before family dinners and before sleep. No matter what he was about to do, Savoie wanted to be high for it. It never occurred to him that he might have a problem. “It was like, ‘You can’t get addicted to weed. It’s the harmless drug,’ ” he recalls.

But after five years of heavy use, Savoie noticed his short-term memory was starting to fray. He avoided talking to people. Worse, festering feelings of anxiety and depression were growing. He tried to mask them with weed, deepening his dependency. He upended his life, quitting his job and breaking up with his girlfriend, trying to find the source of his depression. Nothing worked. “Maybe it’s the drug use,” he recalls thinking, “because I’m constantly relying on it.” (Research shows a link between cannabis use and depression, but causality isn’t clear.) By that time, Savoie was using dabs, a highly concentrated form of marijuana, and he was still grappling with depression. After a minor argument with his sister at the family cabin, Savoie ﬂed and barrelled back to the city in tears. He called a friend to take him to a mental health clinic. Savoie, who had been prescribed antidepressants a couple of weeks earlier, spent two hours with a doctor and was told what he already suspected: he had a dependency on marijuana that was affecting his mental health, and he had to quit.

Cases like Savoie’s are exactly what the federal government is hoping to avoid in its push to legalize recreational marijuana, and they may be the biggest test of whether legalization is ultimately successful. They could also prove to be immensely challenging. That it’s even possible to become dependent on cannabis could come as a surprise to many, especially young people. A survey conducted by the Canadian Centre on Substance Abuse (CCSA), published last year, found that a majority of youth were unaware that cannabis can be addictive and lead to withdrawal symptoms. Marijuana use among young people has declined over the past few years, but Canada still has one of the highest rates in the developed world. Youth are better able to list what they consider to be the benefits of cannabis than the harms. As the country hurtles toward legalization of recreational use this summer, doctors fear the risks of marijuana are still not well understood, and that this ignorance could carry widespread consequences. “I already treat kids who are dealing with the harmful effects of marijuana,” says Sharon Burey, a pediatrician in Windsor, Ont., and vice-president of the Pediatricians Alliance of Ontario. “I’m alarmed at what is happening now, and what may happen after July 1.” The concern is that legalizing marijuana ends up normalizing it, leading to increased use.

The thriving illicit market for marijuana is proof prohibition has done little to discourage Canadians—especially youth—from using the drug. The goal of legalization is to stamp out the black market, and ideally redirect resources previously used to penalize people for marijuana offences to educating Canadians on the potential harms. But legalizing a substance while simultaneously telling Canadians they really shouldn’t be using it is a tricky balance. (Recall the scowling, disapproving faces on government officials earlier this year at the press conference to unveil the marijuana legalization bill.) Doctors are far from the only voices in the discussion, either. Marijuana advocates extol the relative safety of the drug and play up the health benefits, while the industry is set to maximize its profits. Indeed, marijuana producers are betting the opportunity in Canada is bigger than simply moving users from the illicit market to the legal regime. An oft-quoted report from Deloitte pegs the potential market size at $22.6 billion annually, based in part on the finding that 17 per cent of Canadians indicated they might try marijuana once legal. That works out to 40 per cent of the adult population.

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For medical professionals, that’s an alarming statistic. The risk of dependence among those who use marijuana is nine per cent (it’s 16 per cent for alcohol), and for those who start in adolescence, the risk rises to 16 per cent. “The more people who try it, the more people will become dependent,” says Anthony Levitt, chief of the Hurvitz Brain Sciences Program at Sunnybrook Hospital in Toronto. “It’s unavoidable.”

Doctors are especially worried about adolescent use because a growing body of research links marijuana to a range of negative outcomes. Those who smoke regularly double their risk of reporting psychotic symptoms or being diagnosed with schizophrenia in adulthood, especially when there is a personal or family history with mental illness. Long-term use is also associated with problems in attention, memory, impulse control, problem solving and emotional regulation. Regular use also affects the very makeup of the brain, which is still developing in youth. “The evidence is mounting that early-onset cannabis use has a tremendous impact on the structure and functioning of the teenage brain,” according to the CCSA. Though the organization characterizes the cognitive impairments linked to chronic use as “mild,” those who start in adolescence may never fully recover, unlike adults.

As a result, the Canadian Medical Association urged the federal government to set the legal age for consumption at 21, and restrict the quantity and potency of marijuana for everyone under 25. Instead, Ottawa proposed a legal age of 18 and let the provinces and territories impose stricter standards. For the most part, governments have opted to prohibit access for those under 19 (Alberta and Quebec have opted for 18), which represents a compromise of sorts. Since Canadians under 25 are the biggest consumers of marijuana, restricting access would only further entrench the illicit market and continue to subject young people to criminal prosecution. No jurisdiction has proposed to limit the quantity and potency of marijuana to Canadians under 25, however, and some doctors have slammed the federal government for failing to set national standards. “The government appears to be hastening to deliver on a campaign promise without being careful enough about the health impacts of policy,” wrote Diane Kelsall, interim editor-in-chief of the Canadian Medical Association Journal, in an editorial last May.

Levitt, for one, is concerned that health warnings from the CMA and other bodies are lost in the conversation around legalization. “The discussion in the past few years has seemed to provide tacit approval that marijuana is not addictive, or that it’s not a bad addiction to have,” he says. He sees a very different reality in his role as medical director of the Family Navigation Project at Sunnybrook. The program helps families with youth between 12 and 26 dealing with mental health or addiction issues find appropriate care. When families call about an addiction issue, the substance is marijuana in the overwhelming majority of cases.

“What was so unusual was that the youth were aggressive and angry,” Levitt says. If confronted about anything—quitting marijuana, getting a job, returning to school—the youth would lash out with threats, he says, throwing furniture or kicking holes in the walls. Family members start to feel trapped in their own homes, afraid to stoke a confrontation. “When anything would threaten their access to their substance, they became angry,” Levitt says. “It really is someone feeling trapped that they can’t get access to the substance.”

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The Diagnostic and Statistical Manual of Mental Disorders sets out a definition for cannabis dependence, including a strong desire to use marijuana, unsuccessful attempts to cut back and failure to fulfill obligations at work, school or home as a result. Michael, who asked that his last name not be used, first tried cannabis when he was 14, and continued to use multiple times a day for nearly 30 years. Over time, he organized his life around marijuana, choosing a career editing music videos, where marijuana use was acceptable, and turning down more lucrative job offers. His dependence contributed to the end of his first marriage. Michael told his ex-wife he would stop using but ended up buying marijuana a few days later. “It very slowly crept up on me until I had lost all my options in life,” he says. Michael lost his job, and found he couldn’t maintain steady employment. His memory was spotty, and he recalls struggling to spell even simple words in his head. At one point, he lived in a tent in his dealer’s backyard.

Michael tried quitting numerous times, and even attended Alcoholics Anonymous meetings. The sessions helped, but he wasn’t entirely connecting with the stories he heard in AA. (Even in recovery, marijuana is viewed as a more benign substance, and some people joke about being on the “marijuana recovery plan”—using weed as a substitute for alcohol or another drug.) “That was the only time in my life when I wanted to kill myself,” he says. Michael saw in AA that people could overcome their addictions, but he wasn’t entirely committed to the program. “I didn’t feel at home in AA,” Michael says. It wasn’t until a friend introduced him to Marijuana Anonymous, a much smaller group with just a few meetings in Toronto, that Michael was finally able to stop smoking. Michael better related to the stories he heard, and decided to get more involved in the organization. “That gave me a sense of purpose,” he says. “That’s the biggest thing. When I was a pothead in my basement, I felt like I had no purpose.” He hasn’t smoked since July 2010.

While marijuana comes with its own set of risks, it is obviously not as destructive or addictive as alcohol or other substances. But that fact can become a justification to keep using rather than address the problem. Stefan, who lives in London, Ont., started smoking marijuana regularly in university and began to wonder if he had a problem when he noticed he was planning his day around when he could smoke. Eventually, he felt he needed marijuana to feel normal. “I’d smoke to be sober,” he says. Stefan constantly thought about quitting. “I had this battle for years in my head. My brain was saying, ‘It’s way better for you than alcohol or this or that substance.’ ” He quit for brief periods, but a stressful event would prompt him to start again. Sometimes, he picked up the habit again out of boredom. “It’s hard to justify not doing something that I enjoy, especially with all the coverage of it being healthy and great for you.” (He eventually quit for good last year.)

Chronic users can experience withdrawal symptoms, which can cause some people to start again. “The first nine days were a living hell,” Michael recalls. He was racked with night sweats, uncontrollable shaking and a complete loss of concentration. When Savoie decided to quit, he made sure to coordinate with his doctor, since depression has been reported as a symptom. He lost his appetite for the first few days, and what he could eat, he had trouble keeping down. To keep himself busy, Savoie embarked on seven long hikes in seven days. On the first day, he buried all his marijuana paraphernalia in the woods. “I literally dug a grave,” he recalls, “because, as far as I was concerned, it was dead to me.”

Beyond the long-term consequences of habitual marijuana use, some doctors are concerned that legalization could come with unforeseen costs to the public, such as more trips to the emergency room. Jessica Ross, a family physician in Port Perry, Ont., has already seen more adolescents head to the ER complaining of intense abdominal pain, persistent nausea and vomiting. The cause is cannabinoid hyperemesis syndrome (CHS), a condition that affects a minority of frequent users. When Ross first started an independent practice seven years ago, she never came across it. Now, she sees a couple of cases per month. The condition isn’t always diagnosed immediately, since a battery of tests is first performed to rule out other causes. “We have one girl who probably presented to our emergency department eight to 10 times before she ended up getting diagnosed,” Ross says.

Why exactly marijuana triggers this response in some people hasn’t been determined, but the treatment is straightforward. A topical capsaicin cream relieves the nausea, and quitting marijuana will ensure the syndrome doesn’t return. A lack of education, though, can lead to the syndrome persisting. Because marijuana is used as a treatment for nausea, those afflicted with CHS might end up smoking even more in an attempt to feel better—and end up exacerbating the problem.

A study published in Academic Emergency Medicine in 2015 examined the number of emergency room visits by those with CHS in Colorado following the legalization of medical marijuana in 2009. ER visits nearly doubled to 87 per 125,095 patients compared to the period before legalization. The authors note it’s unclear whether marijuana use actually increased or if doctors were just more aware of the syndrome. Patients are also more forthcoming about using the drug as laws liberalize.

Colorado, along with Washington, is a closely watched parallel for Canada, since recreational marijuana has been available there since 2014. In particular, researchers are monitoring the effect on adolescents. To some extent, those on either side of the legalization debate can pick and choose data about prevalence to support their case. Andrew Freedman, who served as Colorado’s director of marijuana coordination until earlier this year, urges caution before leaping to conclusions. “What’s most important is to remain patient and watch trends. As trend lines begin to become worrisome, then you adjust your model to fit best practices,” he says.

Still, the conclusion most have drawn is that youth are not using cannabis any more than they were before legalization. Even the Canadian Paediatric Society is not sounding the alarm. “Colorado and Washington do not appear to indicate a significant increasing prevalence among adolescents,” according to a CPS position paper released earlier this year. (The caveat is that use has not significantly declined in Colorado either, even though many other U.S. states have seen decreases in recent years.)

Freedman credits Colorado’s marijuana youth prevention and awareness campaign for keeping the numbers from climbing post-legalization. The state did make mistakes, though. First, the campaign didn’t launch until after recreational use was legalized. Second, the tone was entirely wrong. Colorado opted for the slogan “Don’t be a lab rat,” implying youth were subjecting themselves to a science experiment by using cannabis, since many of the long-term health effects are unknown. “One of the lessons we learned is that if teenagers see our messaging as a scare tactic, they’ll tend to turn it off,” Freedman says. Colorado rolled out another campaign that instead implied marijuana would impede youth from achieving their goals.

In October, Ottawa announced $36.4 million for an awareness and education campaign, and earlier this year issued a tender for a contractor to develop “national experiential marketing events” centred on cannabis education for youth. The tender called for events to launch in the 2017-18 fiscal year,* but the $2.2-million contract was only awarded to a B.C. branding firm in November, and nothing has rolled out yet. The provinces are pledging to develop their own campaigns, but no efforts have gotten off the ground.

Health Canada also needs to finalize the regulations around cannabis packaging. Public health experts are pushing for plain packages, devoid of branding, which marijuana producers oppose on the grounds that it limits their ability to communicate with customers and makes legal products harder to distinguish from the illicit variety. The federal government has already proposed a strict approach to advertising, effectively banning promotion of cannabis outside of locations where young people aren’t permitted. Marijuana producers can’t employ testimonials or celebrity endorsements, or associate cannabis with a positive lifestyle.

Proposed regulations released in November do not recommend plain packaging, however, and instead endorse “strict limits on the use of colours, graphics and other special characteristics” on packaging to avoid appealing to youth (a consultation period is under way). But if the Liberals are serious about public health, they should enforce plain packaging, says David Hammond, a professor at the University of Waterloo’s School of Public Health and Health Systems. “It’s a good test of their commitment,” he says. Studies show that young people are more influenced by branding on tobacco packages than older users, and establishing branding guidelines (however detailed) creates an unwieldy enforcement job for Health Canada. “It becomes this cat-and-mouse game,” Hammond says, “and it’s not one governments perform particularly well.”

Legalization is, ultimately, an experiment with uncertain outcomes. If cannabis use among youth increases in the coming years, clearly the government will have to reassess its policies. That’s why it makes sense to impose strict standards at the outset, according to some public health experts. “It is far easier to loosen restrictions than it is tighten them,” Hammond says.

Savoie, meanwhile, hasn’t smoked habitually for three months. His depression and anxiety are gone, he feels motivated at work and he’s more outgoing socially. When he was smoking, Savoie avoided talking to people because he felt marijuana heightened his introverted nature and feared his drug-induced state would cause him to say something strange or awkward. His short-term memory, though, has suffered. At work in his role as a web designer, he has to make sure to write everything down. He did smoke at least once since he quit habitual use, though. “It was eye-opening,” he says. Savoie’s anxiety came surging back and he broke into a nervous sweat. “It was direct evidence that I’m okay, I can do without this.”

CORRECTION, Jan. 15, 2018: This story originally contained incorrect information about the timing of the tendering process.

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