Don’t toke and drive

According to polling, many young people feel that marijuana has little impact on their driving skills. A recent study by researchers, including associate professor of physical and occupational therapy Isabelle Gélinas, PhD’95, suggests otherwise.

Story by Becca Hoff, BA'17, MISt'19

January 2019

According to polling done by the Canadian Automobile Association (CAA), one in four young Canadians believes that using cannabis has no impact on their ability to drive a car safely. A recent study from McGill suggests otherwise.

The recent legalization of cannabis could result in more drivers taking to the road after smoking a joint. Isabelle Gélinas, PhD’95, an associate professor of physical and occupational therapy, was part of a team of McGill researchers who examined the effects of marijuana use on the driving ability of recreational cannabis users between the ages of 18 and 24.They measured the drivers’ ability to perform complex driving-related tasks at one-, three-, and five-hour intervals after cannabis consumption (the equivalent of less than a single joint), as well as their self-perception of their comfort level with driving.

The McGill team found that even five hours after inhalation, the participants were impaired in their driving performance, with their perceived ability to drive safely also reduced. The study’s participants did alright in the driving simulation so long as there were no distractions, but problems cropped up when conditions were made more realistic, and the drivers had to contend with unexpected situations.

Says Gélinas, “The key message is that if you inhale cannabis, you shouldn’t be driving. If you do want to drive, you have to wait a certain amount of time before you take the wheel.”She suggests that the results of the study, which was funded by the CAA, could have an impact on future awareness campaigns, noting the value in having “more evidence to properly sensitize the public on the impact of [cannabis] on driving.”

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