The prevalence of traumatic brain injuries such as concussions among students points to a silent epidemic that demands a wake-up call from parents, coaches and other adults, Canadian neurosurgeons and psychologists say.

One in five students in grades 7 to 12 said they’d had a traumatic brain injury that left them unconscious for at least five minutes or required a hospital stay overnight after symptoms, researchers said in Wednesday’s issue of the Journal of the American Medical Association.

si-ilie-gabriela-paint-220-

Teen mood swings after losing consciousness from a brain injury need to be taken seriously, says psychologist Gabriela Ilie. (Jill English/CBC)

The researchers from St. Michael's Hospital and the Centre for Addiction and Mental Health in Toronto surveyed 8,915 students across Ontario in 2011 as part of one of the longest ongoing school surveys in the world.

"It needs to be a wake-up call to say, look, young people are sustaining brain injuries at a very high rate," said the study’s lead author, Dr. Michael Cusimano, a neurosurgeon at St. Michael’s Hospital. "If we want to protect future generations, because our brain really defines how we are … not just as an individual, we need to do something collectively as a society to address this problem."

Of the 464 students reporting a traumatic brain injury in the past 12 months, sports injuries accounted for more than half of the cases, 56 per cent, particularly for boys. Concussions that didn't lead to loss of consciousness or a hospital stay weren't included.

"We need to increase our efforts around sport so that kids get the benefit of sports but don't suffer these negative consequences," Cusimano said. "We know that we still have a significant problem with hits to the head, hits from behind and fighting," in youth hockey.

Sports injuries were the reported cause given by 63 per cent of boys and 47 per cent of girls.

Cause of falls?

Students were also asked about their use of alcohol and cannabis, as well as their grades.

"Kids who use alcohol regularly have three times the odds of reporting the brain injury than those who don't, and those who use cannabis are five times more likely to report the brain injury," Cusimano said.

Students reporting poor grades were around four times more likely to say they'd had a brain injury. The findings were the same across the province and likely hold across Canada and in the U.S, the team said.

The brain injuries could be the result of falling when drunk or an injury from a fight, associations the researchers plan to delve into further as the survey continues.

For those who reported a brain injury in the past year:

  • Falls accounted for 24.7 per cent of injuries in females and 5.1 per cent in males.
  • Collisions involving motor vehicles, snowmobiles and bicycles accounted for less than 10 per cent.
  • Other causes accounted for 18 per cent in females and nearly 11 per cent in males.

"Teens go through so many ups and downs, mood swings," said co-author Gabriela Ilie, a psychologist at the hospital.

"So it's so hard to really pin it down and make up your mind as to you know is there something going on with my son or my daughter? That's why it's important that they see a doctor, especially when it's something as serious as losing consciousness for five minutes."

Emma Fricker, 17, of Mississauga, suffered two concussions, one from downhill ski racing at age 12 and another playing soccer two years ago.

"The first one was pretty life-changing, since I had been unconscious, I was pretty rattled when I woke up and shaken and I didn't really know what was going on I wasn't really myself for two months, my mood swings were outrageous. They were crying and then smiling and laughing and then beyond frustrated and yelling and I had never been a moody kid before," Fricker recalled.  

"The dizziness and the headaches really affected me at school. I couldn't focus for more than a half an hour. It was a ride."

Fricker still skis but has given up soccer.

With files from CBC's Melanie Glanz and Jill English