Young and under the influence: A systematic literature review of the impact of cannabis on the driving performance of youth

Background: Young drivers ages 15-24 continue to constitute a high-risk population for fatal motor vehicle collisions (MVCs) compared to all other age groups. Driving under the influence of cannabis is an important contributor to the high rates of MVCs among youth. Understanding the specific impact of cannabis on the driving performance outcomes of young drivers can inform injury prevention, education, and intervention strategies. Objectives: This systematic literature review (SLR) aims to determine the Class (I- highest to IV-lowest) of evidence and level of confidence (A-high to U-insufficient) in the effects of cannabis on the driving performance of young drivers. Methods: Registered in PROSPERO (#CRD42020180541), this SLR searched seven data bases and appraised the quality and confidence in the evidence using an established research methodology. Results: Class II evidence suggests that THC is likely to reduce mean speed, headway distance, and reaction time; and increase lane and steering wheel position variability among young drivers (Level B, moderate confidence). Conclusions: This study shows that there is a moderate to low level of confidence on the impact of cannabis on the specific driving performance outcomes of young drivers. A need remains for Class I and II studies that focus on the specific effects on young drivers, distinguish between the biological and socially constructed variables of sex and gender, and includes larger and more representative samples.