Teenage boys, already the riskiest of drivers, have a "significantly" higher chance of being in a serious traffic accident if they also have a history of disruptive behaviour, Canadian researchers said.
The researchers said a diagnosis of disruptive behaviour disorders like attention deficit hyperactivity disorder (ADHD) increase the chance of a car accident by one-third among teenage boys, a similar increase to that seen for individuals with epilepsy, diabetes and other diseases.
And that draws attention to the need for greater attention to disorders by the health community and the need to find ways to reduce the risk, said the University of Toronto study, which was published in this week's PLoS Medicine.
The study looked at 3,421 16 to 19-year-old teenage youths hospitalised after a traffic accident, and compared them with a control group of 3,812 male teens admitted for appendicitis over the same period at the same hospitals.
"A history of disruptive behaviour disorders was significantly more frequent among trauma patients than controls," the study said. The researchers, who said the risks also extended to teenage girls, said their estimates were conservative.
The study found that many of the crashes were due to driver error, and distractions like cell phones, caused at least a third of them. "Many drivers overestimate their skills and underestimate their risks. These findings show that the increased risk might be mitigated with better awareness and treatment of ADHD," said Donald Redelmeier, the lead researcher of the study.
Teenage males are the riskiest drivers, despite good health and relatively infrequent driving, with twice the collision rate of the general population, the study said.
"Teenage male drivers involved in serious crashes can also have especially devastating outcomes related to ongoing needs for health care as well as foregone future productivity," Redelmeier wrote.