When it comes to warning our kids about illicit drugs, marijuana presents a special challenge for parents.

We’re up against widespread misperceptions among Canadian youth that using marijuana is relatively safe, and that it’s not addictive. As parents, it can be hard to overturn that false sense of security.

Our kids hear our warnings, for sure, but when they look around at their friends and classmates, they don’t see evidence to back up our concerns. Staggering numbers of their peers (about one in every four) are using cannabis, and most appear to be doing just fine.1

Canada’s recent legalization of recreational marijuana for adults further adds to kids’ perception that marijuana must be safe.

Our kids don’t realize that some of the harmful effects of cannabis take time to show up, and that it does, in fact, come with serious immediate risks too.

We can impress on our teens that cannabis remains illegal for them, but we shouldn’t leave it at that. We need to keep talking to them, regularly, to ensure they understand the potential risks of using cannabis.

Here are some pointers to help you get up to speed with what health researchers know – and don’t know – about the impacts of cannabis on youth. There’s a lot of information here – certainly much more than you’d want to share with your teen all at once. But it will give you plenty of new material to share each time you revisit this important topic with your child.

The risk of addiction is real

According to the Canadian Centre on Substance Use and Addiction, around 30 per cent of Canadian cannabis users under 25 years old are consuming it daily or almost daily,2 putting them in the high risk category for negative long-term effects on health.

Smoking is by far the most common method of consumption.3 About one third of young users have also tried vaporizing – a smoke-free alternative.2

At this point in time – because there’s a scarcity of unequivocal research to rely on – it’s unclear whether smoking pure cannabis joints can lead to lung cancer. Just as with cigarette smoking though, cannabis smokers are also inhaling particulates, carbon monoxide and tar, and frequent users can be plagued by a persistent “smoker’s cough,” excess phlegm production, shortness of breath and acute bronchitis.4

Based on multi-year health surveys, we know that around 10 per cent of cannabis users develop an addiction to cannabis. Cannabis use in adolescence, however, boosts a youth’s chance of dependence higher. Addiction rates are around 17 per cent in people who began using cannabis before the age of 18.3

Many youth, too, are not rolling a pure cannabis joint; they’re smoking spliffs – a combination of cannabis and tobacco – adding the highly addictive power of nicotine to the mix. And nicotine itself is a known carcinogen.

Risks for a teen’s developing brain

While researchers admit they know very little about the long-term effects of cannabis use in adults, there’s widespread agreement that frequent cannabis use can damage an adolescent’s brain.

Speaking on the CBC Radio show Quirks and Quarks, Jeff Edwards, a neuroscientist at Brigham Young University in Utah, explained that the concerns for youth stem from the impact of THC – the main psychoactive compound in cannabis – and how it binds to specific receptors on neurons in the brain.

“If you look at the negative impact of marijuana,” says Edwards, “it’s almost always associated with adolescence. The CB1 receptor that THC binds to is a developmentally regulated receptor, so it’s changing as the brain is developing. And so while both adolescents and adults can develop cannabis use disorder, adults tend to not have these negative long-term outcomes that adolescents do.

“And with adolescents, it’s a little scary because they have an increased chance of abusing other drugs, they can decrease their IQ with chronic marijuana use by an average of about six points, there’s increased anxiety and depression, memory loss and other neurocognitive damage that can occur in adolescents. We don’t tend to see the same types of detriment in adults as we do in adolescents.”5

What’s the “other neurocognitive damage” Edwards refers to? Other scientists have additionally pointed to problems with impulse control as well as concentration and attention problems and related issues with learning in a classroom setting.1

  • Talking with your teen: Check to make sure your child knows that reaching the legal age is no guarantee of safety. In almost all provinces (except Manitoba) the minimum age for legal use of marijuana was set at 19 or 18 to harmonize with the legal drinking age. Health experts have warned, however, that marijuana may have damaging effects on the brain right up until youth reach their mid-20s.1

    If it's relevant, also ensure your child knows that anyone who is pregnant or breastfeeding should not use cannabis at all. It's known to accumulate in the brains of infants in utero and after birth, and is associated with low birth weight, altered neurodevelopment, underachievement in school and behavioural issues.1

Potencies with unknown risks

Today’s marijuana is far more potent that it was 20 years ago. Back then, THC levels in dried weed seldom reached over 10 per cent. Now legal outlets offer adult Canadian consumers varieties of dried cannabis that contain up to 26 per cent THC (based on dry weight of the bud).

But dried weed isn’t the only cannabis product out there. Youth are also heating up highly potent concentrates (oils or “wax dabs”) and inhaling the vapours. Widely available only relatively recently – and only on the underground market – these products go by a variety of names that include shatter, budder, pull-and-snap, CO2 oil or BHO (butane hash oil).

The potency of these cannabis concentrates has no historical precedent. Levels of THC begin around 50 per cent and can reach up to 90 per cent – a level of potency that defies predictions as to their addiction potential and long-term effects.

Explaining her research on cannabis impairment in Colorado, professor Cinnamon Bidwell told CBC Radio, “We are getting blood levels that are higher than I’ve really seen in the literature in terms of their THC and intoxication level. So that raises a concern as to what their exposure is like over time in terms of THC, how their brain and body are adapting to this very acute burst and this very high level of THC exposure. . . . Some of our data suggest possibly higher dependence or problem use in these concentrate users.”6

Concentrates hold potential for other health problems too – problems associated with impurities in the product. Cannabis testing results suggest that youth consuming concentrates produced on the black market are often also consuming the chemical solvents used in its production, along with other contaminants like fungicides and insecticides used in cultivating the source cannabis plants.

  • Talking with your teen: If your son or daughter reveals that they have already tried marijuana, it's important that you gently and patiently explore their motives. You need answers to questions like How often? How potent? and What enticed you to try it? Perhaps your teen is just experimenting occasionally. But if they're using often – once a week or more – or admit to using high-potency concentrates, you should be seriously concerned. It may be that they are trying to medicate anxiety or other troubling emotional issues, and/or that they are on the path to addiction.

The risk of a bad “high” and recurring psychosis

Judging just the right “dose” of cannabis to take can be difficult, especially for the novice. Taking too many puffs or trying a THC concentration that’s too high can lead to cannabis poisoning (i.e. a non-lethal overdose).

Edibles are particularly problematic because it takes longer to feel the psychoactive effects of THC ingested in food. Kids more used to the quick hit from smoking pot may assume a cannabis-infused brownie is not especially potent, and end up ingesting way too much.

Instead of the euphoria and relaxation they were anticipating, kids who overdose can have a frightening experience that may include:

  • hallucinations
  • paranoia (believing others want to harm them) or an acute psychotic episode
  • anxiety, terror or panic attacks
  • frequent vomiting that can take 48 hours to subside
  • disorientation.

The incidence of acute cannabis-triggered psychosis is relatively rare, but it’s cause for real concern for any young person who is affected. Cannabis use – as we’ve known for some time – can trigger schizophrenia in youth who are genetically predisposed to the condition.1

What’s only recently come to light, however, is that using marijuana may actually trigger the later onset of schizophrenia or bipolar disorder in youth who may not otherwise have developed these disorders.

One study of Danish data found that 47 per cent of people who experienced a cannabis-induced psychotic episode lasting two days or more went on to develop either schizophrenia or bipolar disorder. That’s a higher percentage than can be explained by genetic predisposition. The onset was rapid too – within five years for half of those affected.7

  • Talking with your teen: About one in five people, by virtue of their body chemistry, will always have an unpleasant experience when they use cannabis. So you can reassure your child, Not everybody’s doing it! Your child's not likely to be the sole abstainer in their class.

    It's worth reminding your child that when someone is cannabis impaired they're in much greater danger of misjudging risks. They're more likely to misjudge whether it's safe to cross the road, for example, or may abandon their usual principles regarding abstaining from sex. The seemingly small misstep of using cannabis can suddenly create much bigger problems.

Serious risks when combined with driving or alcohol

All youth – whether they’re likely to ever use cannabis or not – need to be warned: Never combine cannabis with alcohol. Drinking alcohol prior to using cannabis dramatically increases the body’s uptake of THC, significantly boosting the impairment potential of even small doses of cannabis and increasing the risk of a cannabis overdose.

Youth who drink, then toke, typically face a load of puke to clean up in the morning. But less fortunate kids have died from alcohol poisoning, because high enough levels of THC in the body can inhibit the normal vomiting reflex that kicks in when alcohol is reaching toxic levels in the blood.

Ingesting cannabis first, then drinking alcohol later, is far less risky – but a teen who is already drunk may not remember which combination is the safer one.

As for driving, cannabis does impair drivers: studies show it doubles or even triples a driver’s risk of being involved in an accident. Most notably, drivers with THC in their system show delayed reaction time, increased lane weaving, and perform more poorly when driving requires divided attention or when encountering complex situations. Canadian cannabis use guidelines recommend cannabis users abstain from driving for at least six hours after using cannabis.1

A youth who drinks, then ingests cannabis, would be a very seriously impaired driver.

  • Talking with your teen: Remind your teen that someone who uses cannabis is not safe to drive for at least six hours – something to keep in mind when they accept rides from friends. Reassure your teen that you are always willing to come pick them up if they ever feel pressured into unwise action by peers, or are ever unfit to drive. Also let them know you will respect their choice to sleep at friend's home, rather than drive.

Dangerous counterfeits

Parents and youth need to be aware that there are synthetic marijuana products available on the illegal market that are extremely dangerous. Two of the most common are called Spice or K2. These products are often not marijuana at all but other dried plant material laced with a variety of toxic chemicals that mimic the action of THC in the brain. Liquid forms of synthetic cannabis are available for vaping as well. In the U.S. products like these have been laced with rat poison, have been found to be 100 times more potent than cannabis, and have caused sudden death and long-term injury.8,9

One of marijuana’s often-touted benefits is that it helps to calm anxiety. (Though in truth, of course, it’s merely a temporary distraction from reality.) So while it’s great to have information to share with your teen, another essential aspect of drug proofing kids involves ensuring they know healthy ways to deal with anxiety or other problems. If you would like help with any issue troubling your teen, Focus on the Family Canada is always here to help. Please call 1.800.661.9800 to arrange a one-time consultation with one of our professional counsellors.

  1. Fischer B., Russell C., Sabioni P., van den Brink W., Le Foll B., Hall W., Rehm J., Room R. (2017): Lower-risk cannabis use guidelines: A comprehensive update of evidence and recommendations. American Journal of Public Health 2017; 107(8). Retrieved from https://ajph.aphapublications.org/doi/full/10.2105/AJPH.2017.303818.
  2.  Canadian Centre on Substance Use and Addiction, June 2018: Canadian Drug Summary – Cannabis. Retrieved from http://www.ccsa.ca/Resource%20Library/CCSA-Canadian-Drug-Summary-Cannabis-2018-en.pdf.

  3. Health Canada (2017): Canadian Cannabis Survey 2017 – Summary. Retrieved from https://www.canada.ca/en/health-canada/services/publications/drugs-health-products/canadian-cannabis-survey-2017-summary.html.

  4. Riberiro, L. and Ind, P. (2018): Marijuana and the lung: Hysteria or cause for concern? Breathe 2018; 14(3): 196-205. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6118880/.

  5. Jeff Edwards quoted from “The Great Canadian Ganja Experiment – The Science of Cannabis.” Quirks and Quarks. CBC Radio, 12 October, 2018.

  6. Cinnamon Bidwell quoted from “The Great Canadian Ganja Experiment – The Science of Cannabis.” Quirks and Quarks. CBC Radio, 12 October, 2018.

  7. Rubin, Eugene. “Acute Marijuana-Induced Psychosis May Predict Future Illness.” Psychology Today, 23 January 2018, https://www.psychologytoday.com/ca/blog/demystifying-psychiatry/201801/acute-marijuana-induced-psychosis-may-predict-future-illness.

  8. “What is Spice / K2? Get the facts on synthetic marijuana.” Spice Addiction Support, 8 January 2018, https://spiceaddictionsupport.org/what-is-spice/.

  9. “Unauthorized product containing synthetic cannabinoids sold from stores in Edmonton.” Government of Canada Recalls and Safety Alerts, 24 August 2018, http://www.healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2017/64304a-eng.php.

Related reading:

BookUnderstanding and Loving Your Child Who Smokes Pot by Stephen Arterburn and Margot Starbuck

Catherine Wilson is an associate editor at Focus on the Family Canada.

*Reference to the individuals quoted does not constitute a blanket endorsement of either the individuals' external work or their respective organizations. Referrals to websites not produced by Focus on the Family Canada are for informational purposes only and do not necessarily constitute an endorsement of the sites' content.

© 2018 Focus on the Family (Canada) Association. All rights reserved. 

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