Cannabis effects while driving

A new clinical trial finds that young Canadians are more at risk of a vehicle crash five hours or less after inhaling cannabis. The trial was funded by the Canadian Automobile Association at the Research Institute of the McGill University Health Centre and McGill University.

Participants’ driving performance, which was tested in a driving simulator, worsened when they were exposed to common distractions on a typical road.

The trial examined the effects of cannabis on the driving ability of 18 to 24-year-old occasional users. CAA polling found that one in five Canadians believe they are as good or better drivers stoned as they are sober.

“This new trial provides important Canadian evidence that cannabis can affect the skills needed to drive safely even five hours after consuming,” said Gary Howard, vice president of communications at CAA.

“The message is simple. If you consume, don’t drive. Find another way home or stay where you are.” While participants showed no significant effects when there were no distractions, when conditions became more realistic, driving-related performance reduced significantly.

Also, the young drivers reported they did not feel as safe to drive after consuming cannabis, even five hours after use. “This rigorous experimental trial adds to a growing body of scientific literature on cannabis use and driving,” said study co-author Isabelle Gélinas, a researcher in McGill’s School of Physical and Occupation Therapy.