In a representative sample of 4,014 Ontario adults, those screening positive for ADHD symptoms reported higher substance use but no more driving after drinking, driving after cannabis use, or collision involvement.
Read this if you want to understand whether ADHD affects driving safety in adults.
No difference in driving incidents between ADHD-positive and ADHD-negative adults
What the researchers found
Of 3,485 licensed drivers surveyed, 3.22% screened positive for ADHD symptoms. Those screening positive were younger, reported more distress, antisocial behavior, anti-anxiety and antidepressant medication use, substance use, and social problems compared to those screening negative.
However, there were no statistically significant differences between ADHD-positive and ADHD-negative groups on any driving outcome: driving after 2+ drinks, driving within an hour of cannabis use, street racing, or collision involvement in the past year.
When a regression model controlled for age, sex, and kilometers driven, ADHD screening status was not associated with collision risk. Cannabis use ever approached but did not reach statistical significance as a collision predictor.
Why it matters
This is the first population-based study in Ontario to examine ADHD screening and driving outcomes in a representative adult sample. The null finding for driving risks is reassuring but should be interpreted cautiously given the limitations of self-report screening versus clinical diagnosis.
The numbers in context
4,014 adults sampled, 3,485 licensed drivers. 3.22% screened positive for ADHD. No significant differences in driving after drinking, driving after cannabis, street racing, or collisions. Cannabis use approached significance for collision risk.
How the study worked
Data came from the CAMH Ontario Monitor, a repeated cross-sectional telephone survey. 4,014 Ontario adults were sampled over 2 years. ADHD was assessed using the Adult ADHD Self-Report Scale (ASRS-V1.1). Multiple psychiatric, substance use, and driving measures were collected.
What this study cannot tell us
ADHD was assessed by self-report screener, not clinical diagnosis. The ADHD-positive sample was small (3.22% of 4,014). Self-reported driving outcomes may underestimate risky behaviors. The telephone survey format excludes people without landlines. These results should be interpreted as preliminary.
How to read the evidence
This is a population-based cross-sectional study, but the ADHD measure was a screening tool rather than clinical diagnosis, limiting its sensitivity.
When this study was published
Published in 2014. Research on ADHD and driving safety continues with more sophisticated methods.
The bigger picture
ADHD has been associated with increased driving risk in clinical samples, but this population-based study did not confirm that association. The difference may reflect selection bias in clinical studies or the use of a screening tool rather than clinical diagnosis in this study.
Questions still open
- Would clinically diagnosed ADHD show a different relationship with driving outcomes? Does ADHD medication use modify driving risk? Would a larger ADHD sample reveal differences that were underpowered here?
Common questions
Why does this contradict other ADHD driving studies?
Does this mean ADHD has no effect on driving?
Read the original research
Attention deficit hyperactivity disorder, other mental health problems, substance use, and driving: examination of a population-based, representative canadian sample.
Traffic injury prevention, 15 Suppl 1, S1-9
Citation
Vingilis, Evelyn; Mann, Robert E; Erickson, Patricia; Toplak, Maggie; Kolla, Nathan J; Seeley, Jane; Jain, Umesh. (2014). Attention deficit hyperactivity disorder, other mental health problems, substance use, and driving: examination of a population-based, representative canadian sample.. Traffic injury prevention, 15 Suppl 1, S1-9. https://doi.org/10.1080/15389588.2014.926341