Canadian study links teenage pot use to increased risk of suicidal behaviour

Scientists at McGill University found a higher rate of diagnosed depression in young cannabis users

A new study suggests teens who regularly smoke weed are at greater risk of developing depression and suicidal behaviour in young adulthood.

Scientists at McGill University analyzed 11 international longitudinal studies involving people aged 18 to 32 who smoked weekly or daily when they were 18 or younger.

They found a higher rate of diagnosed depression, suicide ideation and suicide attempts compared to those who didn’t use cannabis in their teens.

Lead author Gabriella Gobbi says the increased individual risk is modest, but the popularity of pot means a large number of young people could be at risk of developing mental-health issues.

Researchers estimate seven per cent of Canadians between the ages of 18 and 30 are diagnosed with depression that could be linked to prior cannabis use, or roughly 25,000 young people. Researchers found even stronger links to suicidal ideation and suicide attempt, but weaker links to anxiety.

The study consisted of a systematic review and meta-analysis of studies comprising 23,317 individuals. It was done in collaboration with Oxford University and Rutgers University-Camden and published Wednesday in the journal JAMA Psychiatry.

Gobbi says the findings highlight the need for better education on the risks of marijuana.

“We have to do more prevention, to decrease the amount of young people and adolescents that smoke cannabis,” the McGill psychiatry professor says from Montreal, urging education for teens and parents.

Most provincial laws restrict usage to those 19 and older, but about 27 per cent of Canadians aged 15 to 24 — more than any other age group — used cannabis in the last three months of 2018, according to Statistics Canada.

“Since we had legalization, young people continue to smoke as before,” says Gobbi. “So legalization is not the only response. We need to do more prevention.”

Gobbi says the studies included were adjusted for any subjects that may have displayed signs of depression or suicidal tendencies before using pot.

She says adolescents are particularly vulnerable because their brain does not fully develop until age 25.

The findings also dispel misconceptions that weekly pot use is harmless, she adds, noting that scientists found it impossible to differentiate degree of risk between weekly use and daily use.

She explains that the psychoactive property in cannabis — tetrahydrocannabinol, or THC — remains in the body “for a long, long time.”

“THC is a lipid so it stays in the brain and in the body for one week or even more — in some individuals until one month. So smoking a joint is not like drinking two or three beers on a Saturday night,” says Gobbi, also a researcher in the Brain Repair and Integrative Neuroscience program at the Research Institute of the McGill University Health Centre.

Gobbi says there are many more questions to explore, noting the research did not consider alternate modes of consuming cannabis such as vaping or edibles.

She also notes the subjects were teens during the 1980s, 1990s, and 2000s, when the amount of THC content was generally relatively low.

“Now we have joints that have 10, 20, 30 per cent, even more content of THC so we don’t know the impact of the cannabis that we have today on mental health. This is something that of course we have to study more.”

The research was funded by the Canadian Institutes of Health Research and the Quebec Network on Suicide, Mood Disorders and Related Disorders.

If you or anyone you know needs support for depression or suicide-related mental health problems, call the Canadian Assistance in Suicide Prevention 24/7 hotline at 1-888-353-2273.

Cassandra Szklarski, The Canadian Press

Like us on Facebook and follow us on Twitter.

Just Posted

Harrison to replace final incandescent street lights with LEDs

The $186,000 project is the second-phase of a replacement plan for the village

Harrison Hot Springs to consider single-use plastics ban

Village staff will come back to council with a report on what a possible ban could look like

Wonder Pup book series by Chilliwack author teaches kids self-regulation skills

Author Angela Murphy and illustrator Davis Graham release first book Speak Up, Wonder Pup

Agassiz-Rosedale Bridge construction could start in 2021, MLA says

The project is expected to cost substantially more than budgeted in 2017

Fraser Valley developer offering to build barn owl nesting boxes for free

Gore Brothers says anyone with a suitable building can help the threatened raptor

VIDEO: Reading splashes into Agassiz’s Ferny Coombe Pool

The Agassiz Library held its annual Reading in the Pool event Friday, June 14

MPs hear retired B.C. nurse’s petition to change compensation for fatal medical errors

Teri McGrath wants provinces to implement no-fault system for medical errors

Horgan says he’ll still defend B.C. coast after second Trans Mountain approval

Meanwhile, one B.C. First Nation has announced plans for a legal challenge

Metro Vancouver’s air quality could be the worst yet this wildfire season

As wildfire season approached, Metro Vancouver experts predict the air will be an issue for many

Demonstrators on either side of Trans Mountain debate clash in Vancouver

Crowd heard from member of Indigenous-led coalition that hopes to buy 51% of expansion project

Update: Multiple fires along the railway tracks in Pitt Meadows

CP rail has closed tracks while firefighters work

Grieving B.C. mom hopes Facebook message leads to new investigation into son’s Surrey homicide

Criminal Justice Branch didn’t lay charges, concluding no substantial likelihood of murder or manslaughter conviction

B.C.’s measles vaccination program gains traction in May

More than 15,000 doses of the MMR vaccine has been administered across the province

B.C. farmers concerned Agricultural Land Reserve changes choking their livelihood

Dozens voice concerns at special meeting hosted on Vancouver Island

Most Read