Canadian teens who used both alcohol and cannabis were 9.5 times more likely to ride with an impaired driver than alcohol-only users
Among nearly 70,000 Canadian secondary school students, dual use of alcohol and cannabis was associated with 9.5 times higher odds of riding with someone impaired by both substances, with nearly half of dual users reporting impaired driving or riding exposure.
Quick Facts
What This Study Found
Overall, 14.7% of students reported impaired driving or riding (IDR). Prevalence varied dramatically by substance use: 8.0% nonusers, 21.9% alcohol-only, 35.9% cannabis-only, and 49.6% dual users. Dual use was associated with 9.5 times higher odds of alcohol-cannabis IDR compared to alcohol-only use, and 3.0 times higher odds compared to cannabis-only use.
Key Numbers
69,621 students in 182 schools. IDR prevalence: 8.0% nonusers, 21.9% alcohol-only, 35.9% cannabis-only, 49.6% dual use. Dual vs alcohol-only IDR: OR 9.5. Dual vs cannabis-only: OR 3.0. Gender diverse students, older students, and lower SES associated with higher IDR.
How They Did This
Cross-sectional survey of 69,621 students in 182 Canadian secondary schools during the 2021/22 school year. Multilevel logistic regression accounting for school clustering. Interactions tested for gender and age.
Why This Research Matters
This is one of the largest studies to quantify impaired driving exposure among teens using both alcohol and cannabis. The near-50% IDR prevalence among dual users represents a major road safety concern, especially as both substances become more accessible.
The Bigger Picture
The finding that even nonusers report 8% IDR prevalence means all students are at risk from impaired drivers, but dual substance users face disproportionate danger. Road safety interventions should specifically address the combined use scenario.
What This Study Doesn't Tell Us
Cross-sectional design. Self-reported substance use and IDR. Cannot determine the specific IDR situations (e.g., who was driving, relationship to driver). Single school year. Canadian context may differ from other countries.
Questions This Raises
- ?Are safe ride programs accessible to teens in dual-use scenarios?
- ?How do teens perceive the combined impairment risk of alcohol plus cannabis?
Trust & Context
- Key Stat:
- 49.6% of dual users reported impaired driving exposure
- Evidence Grade:
- Very large school-based survey with multilevel analysis accounting for clustering. Cross-sectional design limits causal inference.
- Study Age:
- 2024 study
- Original Title:
- The association between single and dual use of cannabis and alcohol and driving under the influence and riding with an impaired driver in a large sample of Canadian adolescents.
- Published In:
- Traffic injury prevention, 25(6), 765-773 (2024)
- Authors:
- Gohari, Mahmood R(2), Patte, Karen A(4), Elton-Marshall, Tara(3), Cole, Adam, Turcotte-Tremblay, Anne-Marie, Bélanger, Richard, Leatherdale, Scott T
- Database ID:
- RTHC-05345
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
Why is dual use more dangerous for driving?
Alcohol and cannabis impair driving through different mechanisms (alcohol affects reaction time and judgment; cannabis affects attention and lane-keeping). Combined impairment is greater than either substance alone, and users may underestimate the combined effect.
Does this mean all substance-using teens drive impaired?
The study measured impaired driving OR riding with an impaired driver. Many of the teens were passengers, not drivers. However, both situations put teens at risk of traffic injury.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-05345APA
Gohari, Mahmood R; Patte, Karen A; Elton-Marshall, Tara; Cole, Adam; Turcotte-Tremblay, Anne-Marie; Bélanger, Richard; Leatherdale, Scott T. (2024). The association between single and dual use of cannabis and alcohol and driving under the influence and riding with an impaired driver in a large sample of Canadian adolescents.. Traffic injury prevention, 25(6), 765-773. https://doi.org/10.1080/15389588.2024.2342571
MLA
Gohari, Mahmood R, et al. "The association between single and dual use of cannabis and alcohol and driving under the influence and riding with an impaired driver in a large sample of Canadian adolescents.." Traffic injury prevention, 2024. https://doi.org/10.1080/15389588.2024.2342571
RethinkTHC
RethinkTHC Research Database. "The association between single and dual use of cannabis and ..." RTHC-05345. Retrieved from https://rethinkthc.com/research/gohari-2024-the-association-between-single
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.