Children with ADHD are known to go off medications like Ritalin because of side-effects, but researchers suggest that doctors stress the importance of treatment to reduce the risk of traffic crashes. (CBC)

Teenage boys with attention deficit hyperactivity disorder are twice as likely to be involved in a serious car collision compared with the general population, an Ontario study suggests.

The study in Tuesday's issue of the online journal PLoS Medicine looked at 3,421 males between the ages of 16 and 19 who were involved in serious road trauma between 2002 and 2009, compared with a control group of teens admitted for appendicitis.

The researchers suggested listing ADHD the same way as other medical disorders like epilepsy, which require drivers to show they are road worthy to keep their driver's licence.

Study author Dr. Donald Redelmeier, a professor of medicine at the University of Toronto, estimated if the crash risk for teenagers with ADHD could be reduced to that of teens without the disorder then it would prevent about 700 crashes a year in Ontario.

Teenaged girls with ADHD also showed an increased risk of crashes, but the study focused on teenaged male drivers because they have the highest incidence of road crashes, at twice the population average.

"The findings call attention to a widespread, preventable, and costly cause of death and disability," the study's authors concluded.

"Most people know that teenage males are prone to traffic injuries, but the current data show that prevailing adjustments are not sufficient."

Compliance issues for meds

The researchers suggested the family doctors, psychiatrists and community health workers could help by treating ADHD patients with methylphenidate or Ritalin, as well as talking to patients about ways to reduce the risk, such as abstaining from alcohol and avoiding distractions like using cellphones while driving.

The researchers acknowledged limitations of the study, including that they couldn't determine whether the teens with ADHD were taking medication when the crashes occurred.

But children with ADHD are known to go off their meds because of side-effects.

"The medicines only work if the people take them," agreed Dr. Laurence Jerome, a child and adolescent psychiatrist specializing in ADHD at the University of Western Ontario in London. "And when it's in the evening and weekends … we have a compliance problem."

Since the study also did not look at who was "at fault," it is possible that the disorders impair the ability of teens to avoid mishaps initiated by others.

"Most importantly, the observed increase in risk as pedestrians indicates that male teenagers who abstain from driving do not escape the danger of road traffic crashes," the journal's editors said.

Jerome stressed that not everyone with ADHD is a problem driver.

With files from The Canadian Press