Cannabis and driving
Canadian researchers to examine whether cannabis use leads to automobile accidents

June 5, 2018

In January 2018, the Government of Canada announced a $1.4 million investment to support research on the potential impact of legalizing the recreational use of cannabis. Funded through the Canadian Institutes of Health Research (CIHR), the research will help to inform the development of policies and programs aimed at minimizing the negative effects of cannabis use.

One of the common concerns regarding cannabis use is its impact on the user’s ability to drive, and three of the funded research projects will investigate this issue.

Dr. Mark J. Eisenberg, Director of the MD/PhD program within the Faculty of Medicine at McGill University and Staff Cardiologist at the Jewish General Hospital, will analyze how tetrahydrocannabinol (the chemical that causes impairment) affects driving ability. Dr. Eisenberg’s team will also study the consumption patterns associated with recreational cannabis use and driving and identify any knowledge gaps that must be addressed.

“A report by the Canadian Centre on Substance Use and Addiction suggests that youth often believe that the effects of cannabis on driving vary depending on the person,” said Dr. Eisenberg. “Some youth also suggested that driving under the influence of cannabis is not as dangerous as driving drunk. Thus, many youth may underestimate the impairment associated with cannabis use and driving. Given that youth are also major users of cannabis, it is crucial to address the potential dangers associated with cannabis use and driving.”

Dr. Marie Claude Ouimet, Associate Professor with the Faculty of Medicine and Health Sciences at Université de Sherbrooke and Director of Le Réseau de recherche en sécurité routière du Québec, will be investigating the effects of  cannabis legalization on the incidence of impaired driving, including such consequences as crashes, arrests, and convictions ‒ with a special focus on young drivers. Her team will work with knowledge users (police officers, prosecutors, and representatives from the Société de l’assurance automobile du Québec) to explore how best to address these issues. The results will lead to a monitoring system for driving while impaired by cannabis and other drugs that could also be used in other jurisdictions.

“We need to be able to easily know the status of driving while impaired by cannabis in a timely fashion,” said Dr. Ouimet. “How many people were arrested, prosecuted, and convicted for driving while impaired by cannabis? This insight will help us improve prevention strategies for cannabis among the general population, including high-risk groups, such as young drivers.”

Dr. Christophe Huynh, a researcher at the Centre intégré universitaire de santé et de services sociaux du Centre-Sud-de-l’Île-de-Montréal, will examine how substance use habits, driving behaviours, psychological traits, interpersonal relationships, and conforming to gender norms affect young people’s decisions regarding driving after using cannabis. Dr. Huynh and his team will track a cohort of young Canadian drivers and compile data on their use of alcohol or cannabis before driving.

“I want to understand the psychological reasons why some youth drive a car after they’ve consumed cannabis while others don’t,” said Dr. Huynh. “The drug itself doesn’t force them to do it. For example, some youth may have an impulsive personality. When they use cannabis, they may not thoroughly consider the negative consequences of driving afterwards. But an increase in automobile accidents could also be because these youth drive recklessly even when they’re not under the influence of the drug.”

Dr. Samuel Weiss, Scientific Director of the CIHR Institute of Neurosciences, Mental Health and Addiction, has been following this issue closely and expects this research to provide Canadian decision-makers with valuable evidence to support policy development.

“Up to 31% of cannabis users are youth between the ages of 18 and 24,” said Dr. Weiss. “It will be important to understand how cannabis legalization and regulation could affect the decisions that young people make regarding cannabis use, and especially the potential impact of cannabis use on young drivers. These are important consequences that should be considered for the health and wellbeing of all Canadians.”

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