A new study shows teens who drink alcohol or smoke pot have a three to five times higher risk of brain injury.

The study, done by researchers in Canada, surveyed nearly 9,000 Ontario teens.

The results revealed one in five suffered a brain injury at sometime in their lives — six percent in the past year.

But if you've witnessed someone who's had a few too many drinks, it shouldn't be too much of a surprise that intoxication and drug use can increase the risk of injury.

However, the Calgary Herald points out "Researchers can't tell from the survey how the injuries happened. But booze and pot can make people dizzy and disoriented and alter their perception of distance and space."

One of the study's lead authors talked to Canada's CTV.

There's no cause-effect relationship but what this is to say is it could be both.

It could lead to traumatic brain injury but it could also be the other way around.

You resort to alcohol and cannabis as a way of coping with the injury.

Interestingly, the study also found a correlation between grades and risk for concussions.

Pointing out that kids who have poorer grades are seemingly at higher risk than those with better grades.

The researchers define a concussion as a blow to the head that causes the victim to go unconscious for at least five minutes.

A factor in that could cause some transgression in findings for at least five minutes.

As a co-director of the Methodist Concussion Center at the Methodist Hospital System in Houston notes.

It's a common misconception that concussion typically knock people out.

We know that about 90 percent of sports-related concussions do not cause a loss of consciousness.

It's hard to know how accurate the figures are ... because kids reported on their own history.

And any time studies rely on people's memories, that is a limitation.

There are sometimes no symptoms with concussions — an injury that experts have called a "silent epidemic."

But the most common symptoms include headache, dizziness, nausea and confusion.