Among Canadian high school students, those who perceived regular cannabis use as high-risk were 94% less likely to drive under the influence and 91% less likely to ride with an impaired driver.
Traffic safety advocates, youth health educators, cannabis policy researchers
Students seeing great risk were 94% less likely to drive under the influence of cannabis
What the researchers found
Greater perceived risk of regular cannabis use was associated with reduced driving under the influence (DUIC) and riding with a cannabis-impaired driver (RWCD) in a dose-response pattern. Students perceiving great risk had adjusted RR of 0.06 (95% CI: 0.04-0.10) for DUIC and 0.09 (95% CI: 0.07-0.12) for RWCD, compared to those perceiving no risk.
Why it matters
With cannabis legalization, understanding what drives risky driving decisions in young people can inform public health messaging and prevention campaigns.
The numbers in context
Survey response rate: 76.2% (52,103 of 68,415 students grades 7-12). 14,520 in grades 11-12 analyzed. Great perceived risk vs. no risk: adjusted RR 0.06 for DUIC, 0.09 for RWCD. Associations consistent across sexes and urban/rural settings.
How the study worked
Cross-sectional analysis of 14,520 grade 11-12 students from the 2016-2017 Canadian Student Tobacco, Alcohol and Drugs Survey across 9 provinces. Multinomial logistic regression examined associations between perceived risk and cannabis-related driving behaviors.
What this study cannot tell us
Cross-sectional design; self-reported behaviors and perceptions; New Brunswick and territories excluded; risk perception and behavior measured at same time point so direction cannot be determined.
How to read the evidence
Large national survey with strong response rate, though cross-sectional design limits causal inference.
When this study was published
Published in 2020.
The bigger picture
The strong dose-response relationship between risk perception and behavior suggests that changing how young people perceive cannabis-related driving risks could reduce dangerous driving decisions.
Questions still open
- Can educational campaigns effectively shift risk perceptions? Do these associations hold after legalization changes the cultural context?
Common questions
Were there differences between male and female students?
Could changing risk perceptions actually reduce impaired driving?
Read the original research
Cannabis-related driving and passenger behaviours among high school students: a cross-sectional study using survey data.
CMAJ open, 8(4), E754-E761
Citation
Carpino, Melissa; Langille, Donald; Ilie, Gabriela; Asbridge, Mark. (2020). Cannabis-related driving and passenger behaviours among high school students: a cross-sectional study using survey data.. CMAJ open, 8(4), E754-E761. https://doi.org/10.9778/cmajo.20200081