Like many of Canada's elite winter athletes, Spencer O'Brien has suffered a concussion. In fact, several.

The Olympic snowboarder believes her most recent one, which happened a little over a year ago and caused her to miss the rest of the season, was the fifth time she has been concussed while competing.

"It was difficult," she says. "It's such a scary thing, especially with the knowledge we have now about concussions."

Stories like O'Brien's are common among winter Olympians. Like their counterparts in some big-time professional leagues, the ever-increasing speed, contact and fury of their chosen sport puts them at risk of sustaining a brain injury.

After a long period of either ignorance or willful blindness, research advances have helped shift the way concussions are viewed by pro leagues like the NFL and NHL. Both have made rule changes aimed at reducing blows to the head, and concussions suffered by high-profile players like Sidney Crosby have made clear the need for increased safety measures.

But if record-keeping on concussions can still be spotty in the big leagues, that may be even more the case in Olympic sports. There is no central database listing who has suffered a suspected concussion, and the national sport organizations that responded to CBC Sports' requests for concussion data said that information is kept confidential in order to protect athletes' privacy.

Snowboarder Spencer O'Brien believes she has suffered five concussions during her quest for the Olympic podium. (Cameron Spencer/Getty Images)

One in three

In the absence of reliable official data, CBC Sports has done its best to create a portrait of the prevalence of concussions among Canada's potential 2018 Winter Olympians.

Data was gathered from interviews conducted at the Canadian Olympic Committee's athlete/media summit this past June in Calgary, where some athletes made their first and only public acknowledgement or indication that they had suffered a concussion. CBC Sports also examined media reports and social media posts for mentions of suspected concussions.

Different sports, of course, carry different levels of risk. The research focused on athletes from contact, high-impact or speed-driven sports where concussions would be more likely to occur — alpine and freestyle skiing, snowboarding, luge, bobsleigh, skeleton, long- and short-track speed skating, figure skating and women's hockey (men's hockey was excluded because it's too early to guess Canada's roster).

Cross-country skiing, biathlon and curling were excluded, even though athletes in those sports are not necessarily immune to concussions.

Skip Brad Gushue was sent to hospital on Saturday afternoon after losing his footing and slipping on the ice, landing on his head. 1:19

Of the 142 Canadian athletes we looked at who are in the running to compete at the 2018 Winter Olympics, CBC Sports found 48 (one third) have suffered a suspected concussion at some point in their pursuit of the podium.

These are just the documented or acknowledged cases we were able to track down. Many concussions are never reported and experts point out that many may go undetected.

"We've done research where we've looked at mechanisms of injury and we've never seen a big blow," says Dr. Scott Delaney of McGill University's Sports Medicine Clinic. "We've looked back at the tape and thought that... four or five sub-concussive blows are enough to add up to the symptoms of a concussion."

"Roughly 50 per cent of people don't show any overt signs," adds Michael Hutchison, director of the concussion program at the University of Toronto's MacIntosh Sport Medicine Clinic.

"And we also know that symptoms aren't immediate at the time of injury. Sometimes they take a day or two to evolve. So the identification of the concussion is one of the most complex issues surrounding sports."

'You don't have to hit your head'

Ski cross racer Brady Leman didn't immediately know he suffered a concussion after crashing last January.

"As we learn more and more about concussions, you learn that you don't necessarily have to hit your head on the ground or something like that to get a concussion," he says.

"I had a really stiff and sore neck after that, so we weren't really sure if it was whiplash hiding concussion symptoms or concussion symptoms presenting as whiplash, because they can be very intertwined."

Leman returned to competition soon after his injury. Many athletes are able to recover from a concussion and never suffer another one (or any long-term effects) again. Others aren't so lucky.

"We know that people who have suffered a concussion are four to six times more likely to suffer another concussion as compared to athletes in the same sport who've never had a concussion," says Delaney.

Spills are part of the game for slopestyle skier Kim Lamarre, who worries about how concussions could affect her later in life. (Sergei Grits/Associated Press)

Long-term risks

When high-performance athletes suffer a concussion, they must follow a detailed return-to play protocol established by their national sport organization before being cleared to return to competition.

But even though an athlete may be free of concussion symptoms in that moment, there are long-term risks associated with returning — especially if it's done too quickly. Some athletes may push their limits, something they're accustomed to doing in their sports, and attempt to return too quickly, putting themselves at further risk.

"I think the hardest thing as an athlete is not rushing yourself back because we're kind of hard-wired to say 'yes, I'm fine, I'm ready, I'm good to go,'" says Leman.

Research by CBC Sports found that one-third of the 142 Canadian athletes who are in contention to compete at the 2018 Winter Olympics have suffered a suspected concussion at some point in their careers. 4:28

Delaney says it's unclear why the risk of future concussions is higher in those who have had one previously, but says it could be "there is some type of scarring or damage that occurs in the brain that makes the brain more susceptible to injury."

The possible long-term implications worry Kim Lamarre, who says she suffered a concussion while competing a few months after winning a bronze medal in the ski slopestyle event in Sochi, Russia.

"I'm much more scared of getting another concussion because I feel like I can do whatever I want in life after skiing as long as I don't mess up my brain," Lamarre says.

"It's a risk, but I'm just hoping that it won't happen."