New research suggests that people who have experienced at least one traumatic brain injury in their lifetime may be more aggressive on the road.

Canadian researchers found that people who display serious driver aggression, such as making threats to hurt a fellow driver, passenger or vehicle, have significantly higher odds of being involved in a motor vehicle collision that resulted in hurting themselves, their passenger or their vehicle.

"We know already that driver aggression and risk of driving collision are affected by psychiatric factors and substance use, and that this connection is strong, and we know that mental health and substance can be, both, antecedents and consequences of brain injury," Dr. Gabriela Ilie, lead author of the study and a post-doctoral fellow at St. Michael's Hospital, said in a statement. "Through this study, we wanted to examine if a link between traumatic brain injuries and road-related aggression and driving collisions also exists."

A traumatic brain injury was defined as trauma to the head that resulted in loss of consciousness for at least five minutes or overnight hospitalization.

For the study, researchers collected and analyzed data from nearly 4,000 adults between the ages of 18 and 97 years old.

"These data suggest links between TBI and hazardous driving behaviors, but at this early stage we can't be sure if these relationships are causal," Dr. Robert Mann, senior scientist at the Center for Addiction and Mental Health in Toronto and co-principal investigator of the study, said in a statement. "Nevertheless, it appears that a large proportion of the driving population has experienced these injuries, so understanding how trauma to the head affects driving could have important implications for improving traffic safety."

The findings are detailed in the journal Accident Analysis and Prevention.