Addictions experts sound in on common claims about cannabis use

Things you might be curious about as attitudes around cannabis evolve.

Things you might be curious about as attitudes around cannabis evolve

(Credit: iStock/Getty Images)

Attitudes around cannabis products are changing quickly. For decades, the prevailing myths about cannabis have been part and parcel of war-on-drugs propaganda. Films like Reefer Madness depicted it as a psychosis-inducing bane of sanity and civilization. Yet these views have started to undergo a reversal in recent years, prominently marked in Canada by the legalization of cannabis.

A new set of beliefs — that cannabis can cure a wide range of illnesses or has no adverse effects, for instance — are gaining traction. But, according to health professionals, these views can be as misleading as older myths.

Cara Vaccarino is COO of the Edgewood Health Network, a network of centres across Canada that provide mental health and addiction treatment. Jonathan Stea is a clinical psychologist, researcher specializing in cannabis and CBC contributor. We spoke with both of them to get to the bottom of some of the most prominent claims surrounding cannabis today.

"Cannabis is a gateway drug"

One classic cannabis myth that persists is that it's a "gateway drug" — that using it is the first step on the way to abusing more dangerous substances, and that the toke is the tip of a slippery slope ending in ruin.

Jonathan Stea is skeptical. "The gateway hypothesis assumes linear causality but, in reality, what leads to substance use is multi-causal," he says. "There is some data that cannabis [use] precedes other drug use, but it doesn't mean that it causes other drug use."

Cara Vaccarino points to a 2016 review published in The New England Journal of Medicine that offers physiological evidence that cannabis use can affect dopamine reactivity in the brain, priming it for disordered substance use later in life. However, the study also notes that alcohol and nicotine would fall under the same categorization.

"Cannabis isn't addictive"

Both experts assert that cannabis addiction does exist. The Diagnostic and Statistical Manual of Mental Disorders (known as the DSM-5), the standard manual for diagnosing and treating psychological disorders, includes cannabis in the category of substances subject to "substance use disorder." Criteria for cannabis use disorder, like other substance use disorders in the DSM-5, include cravings for the substance; failure to stop or reduce using, even when you want to; and not managing to do what you should be doing in your other roles and relationships.

Stea notes that it's commonly believed that cannabis addiction is "merely psychological," but that this is also false. As with other addictive substances, cannabis dependence can lead to physical withdrawal symptoms if and when people attempt to stop or reduce use.

How addictive is cannabis? According to Stea and Vaccarino, the drug has approximately a 10 per cent conditional prevalence rate, meaning that one in ten people who use cannabis may develop some kind of use disorder with it. This is a real risk, but Vaccarino says that "relatively speaking, marijuana is one of the least addictive drugs we see." Cocaine and heroin both pose significantly greater risks of addiction than cannabis, she says, while "the most addictive are cigarettes and alcohol."

Cannabis withdrawal symptoms also tend to be less severe than some other drugs. Whereas withdrawal from opioids or alcohol can be painful and in some cases lethal, cannabis withdrawal is more like nicotine withdrawal, Stea notes. According to the Centre for Addiction and Mental Health (CAMH), symptoms can include irritability, anxiety and disturbed sleep.

"Cannabis is a remedy for everything"

One of Vaccarino's main concerns is the proliferation of beliefs about cannabis' medical properties. Many people have come to believe that the plant is an appropriate treatment for conditions as varied as anxiety, depression, PTSD, obesity, glaucoma and insomnia. Yet the scientific evidence for these treatments is mixed, she says.

Stea says that the question is much more complex than simply, "Is cannabis good or bad?" Cannabis contains hundreds of different chemicals, and they don't all have the same effects. For example, Stea notes, cannabidiol or CBD (one chemical compound contained in the cannabis plant) has been found to have some properties that may be therapeutic for conditions such as anxiety and depression, whereas there is evidence that THC (another compound in cannabis) can worsen these conditions.

This is all to say that the science of cannabis is complex and incomplete, and therefore it's important to do some research and consult a physician before using cannabis therapeutically.

"Cannabis use has no harmful effects"

In addition to presenting a danger of addiction, cannabis also may pose other health risks, which include, but are not limited to:

Car accidents: Cannabis use impairs reaction times and makes you more likely to crash your vehicle. Don't use and drive.

Complications in pregnancy: Evidence suggests that using cannabis during pregnancy can adversely affect the development of the child and therefore should be avoided.

Mental health issues: While a causal link between cannabis and these mental health issues hasn't been established, it's worth keeping in mind that regular cannabis use has been associated with an increased risk of anxiety, depression and psychosis. Young people under the age of 25 and those with other factors that predispose them to mental illness or addiction should be especially careful; Vaccarino says that they are particularly vulnerable to the adverse effects of cannabis.

What does it all mean?

Both Stea and Vaccarino believe that prohibition was a harmful approach to the issue of cannabis use. However, even though cannabis is now legal, we shouldn't assume that using it is risk-free.

Both experts reiterate that scientific cannabis research is still in its early stages, meaning that we simply don't have as much well-substantiated knowledge about the effects of cannabis as we do about other legal substances such as alcohol and tobacco.

Stea recommends consulting CAMH's guidelines for lower-risk use. These guidelines state that teenagers should delay using cannabis for as long as possible. According to the Government of Canada: "The brain does not stop developing until around age 25. The younger you are when you begin cannabis use and the more often and the longer you use it, the more likely that it will have a bigger impact on your brain."

If you currently use cannabis, it's worth monitoring whether your use is becoming problematic. One way to do so is to consult the DSM-5 criteria for substance use disorders to see if they apply to your cannabis use. Other options recommended by Stea are to consult your friends and family, and to consider your motives in using the substance. If you're using cannabis to escape difficult thoughts or emotions, Vaccarino says, this is a good indicator that your use might be problematic.

Clifton Mark is a former academic with more interests than make sense in academia. He writes about philosophy, psychology, politics, and pastimes. If it matters to you, his PhD is in political theory. Find him @Clifton_Mark on Twitter.


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