Marijuana (Cannabinoids)

Driving under the influence of cannabis

Past studies on the impact of driving under the influence of cannabis on traffic safety showed that during the acute period of intoxication, cannabis diminishes driving faculties and raises the risk of collision.

Researchers from University de Montreal, in Quebec studied the association between impulsivity or sensation-seeking and the risk of driving under the influence of cannabis.

First, the details.

  • 83 men were observed in driving simulation tests and questioned about their driving history.
  • Dangerous driving habits (eg, risky driving, aggressive driving, and negative emotional driving), behaviors observed in a driving simulator, psychological predictors, and crash involvement were reported by the participants and recorded.
  • Men were selected because statistics show they engage more often in dangerous driving and driving under the influence of cannabis compared to women.

And, the results.

  • 35% of the men were involved in at least 1 driving accident in the previous 3 years.
  • Furthermore, 30 participants admitted using cannabis and 80% of those users reported at least 1 incidence of driving under the influence of cannabis in the previous year.
  • Individuals scoring high on impulsivity or sensation-seeking scales demonstrated an elevated risk of driving under the influence of cannabis.

The bottom line?
“Our study found that men with self-reported driving under the influence of cannabis tend to be associated with an increased risk of being involved in a car accident,” concluded the authors.

Others have reported an association between smoking marijuana and the increased risk of having a driving accident. And several countries in Europe have legal blood level limits for cannabis. The contribution of this study is that it suggests that men who are most likely to drive impulsively are also most likely to get behind the wheel while they’re high.

3/28/09 20:15 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.