TORONTO — Renowned concussion specialist Dr. Charles Tator says he disagrees with Gary Bettman's statement before a parliamentary panel where the NHL commissioner questioned any direct link between multiple hockey concussions and chronic traumatic encephalopathy (CTE), a degenerative brain condition associated with repeated blows to the head.

Tator, a University of Toronto neurosurgery professor, said Thursday that there is a conclusive link.

"In my view there is," Tator said. "We don't know how many players with multiple concussions will get it. That's an important rider."

CTE, which can only be diagnosed after death with a brain autopsy, can be profoundly debilitating with symptoms that include memory problems, personality changes, aggression and depression. Bettman weighed in on the link issue on Wednesday in Ottawa.

"I don't believe there has been, based on everything I've been told — and if anybody has information to the contrary, we'd be happy to hear it — other than some anecdotal evidence, there has not been that conclusive link," Bettman said.

Tator said that information is available on the Canadian Concussion Centre website (www.canadianconcussioncentreuhn.com), adding he'd be happy to meet with Bettman to discuss further if interested. He also dismissed the suggestion that there has not been a conclusive link.

"It's spelled Steve Montador," Tator said. "Just repeat the Steve Montador case as a retort to what Bettman says. How many Steve Montadors does he need to convince him of the relationship?"

Montador, who played 571 career NHL regular-season games, was diagnosed with CTE after his death in 2015. He was 35.

"I personally counted in Steve Montador's records that he had at least 19 concussions and his brain at autopsy showed CTE," Tator said. "So why doesn't Gary Bettman acknowledge that?"

A special committee of MPs has spent months holding hearings on the issue of concussions in sports and a report is expected to be tabled in the coming weeks. Several experts and athletes appeared before the cross-party panel and Bettman and his deputy Bill Daly were the final witnesses.

The committee has focused on amateur athletics but could recommend concussion protocols for pro sports.

The subject of the link between athlete concussions and CTE has also been a hot topic on the gridiron in recent years.

In November 2017, CFL commissioner Randy Ambrosie said there is not enough evidence to confirm a connection between football head injuries and CTE. 

However, Jeff Miller, the NFL's top health and safety officer, acknowledged the link during a discussion on concussions convened by the U.S. Congress in March 2016. It marked the first time a senior league official conceded football's connection to CTE.

Bettman, meanwhile, told the parliamentary panel that hockey is safer for players and different in terms of physical contact from football, where there are repeated blows to players' heads.

Tator noted that more football player brain samples have been examined than those from hockey players.

"So the information is, let's say, less compelling," he said. "But in my view, it's sufficiently documented already to say, 'Yes, in some players, CTE is from repetitive blows to the head.'"

The NHL has faced criticism for its handling of head injuries despite a long list of rules, studies and league-player committees focused on safety. The league reached a settlement last year with hundreds of retired players who claimed harm from head injuries while playing, but the NHL did not admit fault or wrongdoing.

"We have said definitively that repetitive concussions in some hockey players cause CTE," Tator said. "We have had other players who have had dozens of concussions — literally dozens — who don't have CTE. And that's the frustration is that not everyone gets it and we have not yet learned who's going to get it and who isn't.

"Some brains can tolerate more blows to the brain than other brains. There's a great individual variation."

Awareness of concussions and CTE has risen significantly in recent years and researchers have been delving deeper into the subject.

"We see patients who have a single concussion who have symptoms afterwards for years and years," Tator said. "Then we see other people who've had dozens of them and don't show any deterioration clinically and at autopsy their brains are clean. So that, we haven't figured out yet — why some get it and some don't.

"But there is no doubt in our view that some do have brain degeneration called CTE after repetitive blows and unfortunately many of them are very good athletes."

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Follow @GregoryStrongCP on Twitter.

With files from Canadian Press news reporter Jordan Press in Ottawa.

Gregory Strong, The Canadian Press