If one survey of teens in Ontario, Canada, is any indication, as many as one in five seventh-through-twelfth graders has experienced some kind of traumatic brain injury in his or her life.


Published in the Journal of the American Medical Association, researchers from St. Michael's Hospital found that one in five teens reported ever experiencing a traumatic brain injury (including concussion) that required overnight hospitalization or that caused them to become unconscious for at least five minutes. And more than half of these incidents were from sports, such as ice hockey, skateboarding and soccer.


"Traumatic brain injury is preventable," study researcher Dr. Gabreila Ilie, a post-doctoral fellow at St. Michael's Hospital, said in a statement. "If we know who is more vulnerable, when and how these injuries are occurring, we can talk to students, coaches, and parents about it. We can take preventive action and find viable solutions to reduce their occurrence and long-term effects."


The study involved evaluating data from 9,000 teens in grades 7 through 12 in Ontario. In addition to finding that 20 percent of the teens reported having experienced a TBI in the past, 5.6 percent of them said that they'd experienced a TBI in the last year alone.


Researchers found that certain factors upped the risk of experiencing TBI. For instance, boys were more likely than girls to experience TBI. And more boys experienced TBI as a result of sports -- 63.5 percent -- than girls -- 46.9 percent.


Teens who drank alcohol on at least an occasional basis or were regular marijuana users (using it 10 or more times in the last year) also had higher risks of experiencing TBI. Specifically, alcohol use raised the odds of experiencing TBI in the last year by five times, and marijuana use raised the odds of experiencing TBI by three times.


There has been a wealth of research looking into the possible risks -- and risk factors -- of concussions and other traumatic brain injuries in kids and teens. One study published last year in the journal Brain Injury showed that concussions can impair short-term memory in teens for at least six months, and these symptoms are worse in teens than kids or adults, U.S. News reported. And in a study of children ages 8 to 15, researchers from Ohio State University found that concussion-related memory problems can last even a year after the concussion occurred, the Associated Press reported.


As high-impact sports, football and hockey have unsurprisingly made headlines in regard to concussions. But recent studies have also been evaluating the potential effects of soccer injuries: One study in the American Journal of Sports Medicine showed that concussions from soccer injuries are experienced twice as often by girl soccer players than boy soccer players. And a Radiology study that came out earlier this year of amateur adult soccer players showed that heading the ball seems to be a particular culprit in these brain injuries associated with soccer.