Young Drivers Who Use Cannabis at Higher Risk of Collisions

It has been suggested that cannabis use increases risk of driving collisions through affecting braking and choice reaction time; causing impairment of lane position, disrupting head-way and dynamic tracking; distorting time perception; reducing divided and sustained attention; and increasing caution. 

A recent Canadian study, published just two days before cannabis was legalized across the country, investigated the impact of cannabis use on driving performance in young recreational users.

The study investigated 45 recreational marijuana users between the ages of 18 and 24. Participant’s driving reflexes were tested in a driving simulator with no cannabis in their system, and then one, three and five hours after inhalation of a standard 100-mg dose of cannabis through a vaporizer (a typical joint is 300-500 mg of dried cannabis). 

Participants were also asked to rate perceived driving ability and safety at each stage of the experiment.

Results found that although cannabis use made no significant difference when it came to simple driving actions such as braking, steering and maintaining a steady speed, complex driving-related performance, such as reacting to avoid sudden obstacles, was affected at all time points after cannabis use. 

Findings from the self-reported driving ability and driving safety showed that participants in this trial did not perceive themselves to be as safe to drive at 1, 3 and even 5 hours after cannabis use.

Overall the research highlights the importance of adhering to the guidelines on driving after using cannabis and waiting at least 6 hours before getting behind a wheel.