Cannabis and the teen brain

The parts of the adolescent brain that develop first are those that control physical coordination, emotion and motivation. The pre-frontal cortex, the part of the brain that controls reasoning and impulses, does not fully mature until around the age of 25.

It’s as if, while the other parts of the teen brain are shouting, the prefrontal cortex is not quite ready to play referee. This can have noticeable effects on teen behaviour, such as:

  • difficulty holding back or controlling emotions
  • a preference for high-excitement and low-effort activities
  • poor planning and judgement (rarely thinking of negative consequences)
  • more risky, impulsive behaviours, including experimenting with drugs and alcohol

During the adolescent years, your teen is especially susceptible to the negative effects of any and all drug use, including cannabis. Scientific evidence shows that the use of cannabis during the teen years can interfere with school performance and well-being.

Teens are more likely to engage in risky behaviours than any other age group. Risk-taking by teens can include drug use, binge drinking, dangerous driving (e.g. texting, driving while high or being a passenger with a high driver) and engaging in unsafe sex.

Cannabis and driving

It is illegal to drive while impaired by cannabis. Drug-impaired driving has the same penalties as alcohol-impaired driving. Yet many young people still get behind the wheel after smoking pot. In 2011, 12.6% of young Canadians aged 15–24 admitted to driving after using cannabis while 10.7% reported driving after drinking.

A 2016 survey revealed that 19% of 16 to 19 year olds who had been a passenger in a car driven by someone who had consumed cannabis vs 17% who had been a passenger in a car driven by someone who had consumed alcohol.

Data from a recent roadside survey in Ontario revealed that cannabis was the most common illegal drug present among young drivers.

Cannabis use affects decision-making and judgement as well as the process of acquiring knowledge and understanding, and the process of when the brain tells certain muscles and limbs to move, otherwise known as cognitive and motor functions; this is a safety hazard for drivers.

Being a passenger in a car with a driver who has used drugs or alcohol can lead to consequences just as tragic as driving when impaired.

Cannabis and alcohol

While some teens may argue that cannabis is safer than alcohol, research shows that teens don’t typically use alcohol OR cannabis; they use both, often at the same time25—a dangerous combination.

The use of cannabis alone is enough to impair judgement. The biggest impact of mixing cannabis and alcohol is the significant increase in impairment of judgement. The level of intoxication and side effects experienced can be unpredictable. When cannabis and alcohol are used at the same time, there is a greater likelihood of negative side effects occurring either physically or psychologically (panic, anxiety and paranoia).

The use of both alcohol and cannabis before driving can greatly increase the risk of getting into a car accident.

This is similarly the case when mixing cannabis and other drugs.

A doctor’s point of view

“As a psychiatrist who specializes in people with addictions and mental illness, we see an increasing number of young people between the ages of 17 to 25 coming to our psychiatric facility with new onset psychosis and mood disorders in the context of heavy and persistent marijuana use. Unfortunately, we see much harm of marijuana use in youth and those with pre-existing mental illness. The best strategy is to prevent the development of problem marijuana use in the first place—the risks are high and parents should know about available treatment options should kids need it.ˮ

—Dr. Tony George, Chief of Addictions, Centre for Addiction and Mental Health (CAMH)

Information originally appeared in Drug Free Kids Canada’s Cannabis Talk Kit.