For teenager Samantha Yurechuk, it started as just another scramble for the puck. She collided with a player, hit her head on the ice and suffered a concussion - unaware the injury put her at risk of mental decline decades later.
As the 14-year-old opened her eyes under the glare of the arena lights two weeks ago today, the trainer of the Brampton Canadettes bantam AA team rushed over, leaned down and asked: "What city are you in?"
"What's a city?" she replied.
"I started to feel nervous," said the Grade 9 student from Orangeville, Ont., about an hour northwest of Toronto. "I started to think there was something wrong."
Samantha, who has fully recovered, is one of the estimated 10 per cent of hockey players who suffer a concussion every year.
On hockey rinks, soccer pitches, toboggan hills and other sporting arenas across Canada, concussions are a known risk of the game. Conventional thinking used to be that athletes who suffer a single concussion bounce back unscathed.
But Canadian research published in the online journal Brain this week found that even one major concussion can haunt sufferers into midlife and beyond through memory decline, poorer motor skills and slower reaction time.
The research is a warning that should prompt hockey parents to re-evaluate the risk they allow their children to take for a game deeply entwined with Canadian identity.
"The effects of concussions have been ignored for the last 40 years," said Louis De Beaumont, the study's author and a clinical neuropsychologist at the University of Montreal.
Adam Wolman, a Toronto real estate broker, didn't wait for a study to tell him that concussions could be dangerous. He was concerned about their effects after his 14-year-old son, Sam, suffered two of them, one severe.
After seeing a specialist, the family adopted the cautious approach and took Sam, who has fully recovered, out of contact hockey a year ago. He now plays house league for fun.
"We didn't want to risk Sam having problems later in life," Mr. Wolman said. "Most of the kids playing select and hockey in the A levels today will continue to play when they are in their 20s. The majority of them will probably play in non-contact leagues and pick-up games. It's unfortunate that there isn't a higher level non-contact option for kids in their teens."
Most parents aren't like Mr. Wolman. Despite the risks, the vast majority keep their children in the game, even after a couple of concussions.
"I'm amazed at what risks people will take in the name of sports. It is mind-boggling," said Brian Webster, a brain injury lawyer based in Vancouver, who hears from parents who want to sue after their children have suffered concussions from sports. "… When you put your children in sports, you should really seriously try and understand the risks and the benefits, and try to minimize the risks without losing the benefits. But don't pretend they're not there."
The 'scientific facts'
The University of Montreal researchers managed to quantify these risks by first tracking down athletic and alumni associations to find subjects: 19 healthy former Canadian university athletes who had suffered at least one concussion in early adulthood and 21 former athletes who had never had a concussion.
The researchers tested the former athletes' motor control, long-term memory and how well they followed simple verbal and written commands. The results were compelling: Those who had concussions had poorer performance in memory tests, delayed responses to unpredictable events and were slower at hand-control tests than those who never had a concussion.
Further research on more patients and the passage of time is required to determine whether concussions cause the more sinister effect of Alzheimer's disease, which leaves a tangled mass of fatty proteins inside a shrunken brain.
Since the study was based on a concussion grading system most Canadian doctors no longer use, some believe the findings may apply only to those who suffered more severe concussions. Still, experts say the study must be taken seriously.