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

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

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.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Motorists breaking travel rules can be fined $230 for failing to follow instructions or $575 if the reason for travel violates the essential travel health order, at this Highway 3 check area near Manning Park. Photo RCMP
RCMP begin stopping drivers on BC highways – check point at Manning Park

Four check points are set up Thursday May 6 around the province

Dr. Bonnie Henry B.C.'s provincial health officer, updates the COVID-19 situation at the B.C. legislature, April 29, 2021. (B.C. government)
Province ‘ramping up’ COVID-19 vaccination effort in hard-hit Surrey

‘Door-to-door’ registration program in the works, says Dr. Bonnie Henry

Serena Deol, Jaspreet Deol, Madison Sweeney and Tanveer Pannu (pictured clockwise from top left) are Surrey United soccer players recruited to the University of Fraser Valley. (submitted photos)
Surrey United soccer quartet sign to play for UFV Cascades

Three of the university’s recruits are Panorama Ridge Secondary students

John Paul Fraser, executive director of the BC Salmon Farmers Association. (Screen shot)
Salmon farmers warn Surrey jobs on line as feds end Discovery Islands operations

344 full-time jobs at risk in Surrey and 1,189 B.C.-wide

White Rock’s Joan Bywater shows the setup she uses when participating in online paint parties hosted by the Seniors Come Share Society. (Contributed photo)
PHOTOS: Virtual gallery showcases inspirations of Semiahmoo Peninsula seniors

‘What is art if not something that motivates more art?’

Protesters attempt to stop clear-cutting of old-growth trees in Fairy Creek near Port Renfrew. (Will O’Connell photo)
VIDEO: Workers, activists clash at site of Vancouver Island logging operation

Forest license holders asking for independent investigation into incident

Starting Tuesday, May 11, B.C. adults born in 1981 and earlier will be able to register for a vaccine dose. (Haley Ritchie/Black Press Media)
BC adults 40+ eligible to book COVID-19 vaccinations next week

Starting Tuesday, people born in 1981 and earlier will be able to schedule their inoculation against the virus

Parks Canada and Tla-o-qui-aht Tribal Parks dig the washed up Princess M out from sand along the south shore of the Pacific Rim National Park Reserve. (Nora O’Malley photo)
Rescue attempt costs man his boat off Pacific Rim National Park Reserve

Coast Guard response questioned after volunteer responder’s speedboat capsizes in heavy swells

Al Kowalko shows off the province’s first electric school bus, running kids to three elementary and two secondary schools on the West Shore. (Zoe Ducklow/News Staff)
B.C.’s first electric school bus making the rounds in Victoria suburbs

No emissions, no fuel costs and less maintenance will offset the $750K upfront expense

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

The Aquilini Investment Group has agreed to a proposed contract of five years to run the Abbotsford Centre. (File photo)
Proposal to run Abbotsford Centre offered to Canucks ownership group

Planned five-year contract to cost city $750K annually, starting Jan. 1, 2022

Road sign on Highway 1 west of Hope warns drivers of COVID-19 essential travel road checks on the highways into the B.C. Interior. (Jessica Peters/Chilliwack Progress)
B.C. residents want travel checks at Alberta border, MLA says

Police road checks in place at highways out of Vancouver area

Victoria police say the photo they circulated of an alleged cat thief was actually a woman taking her own cat to the vet. (Black Press Media File Photo)
Photo of suspected cat thief released by Victoria police actually just woman with her pet

Police learned the she didn’t steal Penelope the cat, and was actually taking her cat to the vet

Most Read