Study of the Day: Smoking Pot Doubles Chances of a Car Crash

A new meta-analysis of nine studies suggests that the consumption of cannabis impairs motor tasks that are important to safe driving.

main Kshishtof shutterstock_88579600.jpg

PROBLEM: Previous observational studies have failed to separate the effects of alcohol and marijuana use on the risk of vehicle collision.

METHODOLOGY: Researchers from Dalhousie University in Canada reviewed nine previous studies with a total sample of 49,411 people to see if the consumption of cannabis, the world's most widely used illicit substance, increases the risk of a motor vehicle collision. They focused on trials that involved crashes that took place on a public road and involved one or more moving vehicles, including cars, trucks, and motorcycles. They also concentrated on studies that included driver blood samples and direct self-reports.

RESULTS: The vehicle collision risk of people who smoke pot within three hours of driving is nearly double the risk of drivers who are unencumbered by drugs or alcohol. There is also a substantially higher chance of an accident for motorists aged 35 or younger.

CONCLUSION: Marijuana users are twice as likely to cause a car crash as sober drivers.

IMPLICATION: The consumption of cannabis impairs motor tasks that are important to safe driving.

SOURCE: The full study, "Acute Cannabis Consumption and Motor Vehicle Collision Risk: A Systematic Review of Observational Studies," is published in the British Medical Journal.

Image: Kshishtof/Shutterstock.

Presented by

Hans Villarica writes for and produces The Atlantic's Health channel. His work has appeared in TIME, People Asia, and Fast Company.

How to Cook Spaghetti Squash (and Why)

Cooking for yourself is one of the surest ways to eat well. Bestselling author Mark Bittman teaches James Hamblin the recipe that everyone is Googling.

Join the Discussion

After you comment, click Post. If you’re not already logged in you will be asked to log in or register.

blog comments powered by Disqus

Video

How to Cook Spaghetti Squash (and Why)

Cooking for yourself is one of the surest ways to eat well.

Video

Before Tinder, a Tree

Looking for your soulmate? Write a letter to the "Bridegroom's Oak" in Germany.

Video

The Health Benefits of Going Outside

People spend too much time indoors. One solution: ecotherapy.

Video

Where High Tech Meets the 1950s

Why did Green Bank, West Virginia, ban wireless signals? For science.

Video

Yes, Quidditch Is Real

How J.K. Rowling's magical sport spread from Hogwarts to college campuses

Video

Would You Live in a Treehouse?

A treehouse can be an ideal office space, vacation rental, and way of reconnecting with your youth.

More in Health

Just In