Description:

Background: While some studies show that smoked cannabis can impair cognition and driving performance, there is a gap in research examining the effects of edibles. The objectives of the study were to examine (1) when cognition and driving are most compromised; and (2) for how long they are compromised following edible consumption.

Methods: Young drivers were recruited if they were between the ages of 19 and 30 years, had no history of substance abuse, consumed less than 10mg of cannabis once per week, did not have sensory or motor deficits or contraindicatory medical conditions (e.g., seizures). Participants completed a questionnaire, cognitive, motor and visual tests, and drove on the car simulator, at 5 different time points (baseline, 1.5, 2.5, 4- and 6-hours post-edible consumption).

Results: 50 young drivers were recruited; average age was 23.8 years. Visual attention, visual processing, decision making and memory were significantly poorer at 1.5 and 2.5 hours compared to 4- and 6-hours. Reaction time on the driving simulator was the slowest at 1.5 hours compared to 4 (p=0.046) and 6 hours (p=0.005). Participants also made significantly more speed regulation and lane maintenance errors at 1.5 hours compared to 4- and 6-hours. Approximately 30% of participants crashed at 1.5 hours compared to 44% at 2.5 hours, 58% at 4 hours, and 16.0% at 6 hours. At baseline, all participants felt safe to drive (100.0%), however, only 4% felt safe at 1.5 hours, 6% at 2.5 hours, 18% at 4 hours and 36% at 6 hours.

Discussion and conclusions: This study shows that 10mg of cannabis-based edibles can impair cognition and driving performance, with effects lasting up to 6 hours post consumption. While studies have focused on driving, the effect on cognition likely applies to worker productivity and safety in the mining and engineering sectors.

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Dr. Alexander Crizzle

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