Traumatic brain injuries such as concussions can affect the human brain in ways were are just beginning to understand. A new study suggests that, for teen TBI victims in California, it can lead to drug and alcohol abuse.

Researchers examined data from an ongoing study of drug use among high school students in Ontario, Canada. They selected 6,383 teens’ medical history. All of the subjects were in ninth through 12th grades. Some of the teens had suffered a serious TBI, which the scientists defined as knocking the victim unconscious for at least five minutes or forcing them to spend at least one night in the hospital.

According to the data, teens with such a TBI in their past were at least twice as likely to have tried illegal drugs like cocaine, ecstasy and LSD. They were also twice as likely to use medications they were not prescribed, like painkillers and ADHD medicine, than their peers. Finally, the study reported that the teens with a history of TBI were 2.5 times as likely to smoke cigarettes or binge drink alcohol.

This suggests that there could be a link between brain injury at a young age and substance abuse. What we don’t yet know is why such a link might exist. Could the TBI victim be attempting to self-medicate to treat lingering symptoms? Or did the TBI somehow affect the victims’ personalities, making them more prone to risky behavior?

Studies like this one contribute, brick by brick, to our understanding of how brain injury harms victims. They could someday lead to more effective treatments and methods of prevention.