Dr. Ann McKee, a concussion specialist, wants the hockey community to step up its game when it comes to posthumous brain donation.
McKee, the chief of neuropathology at VA Boston and director of Boston University's CTE Center, has been at the forefront of football concussion research for years -- but she has yet to see the hockey community donate brains posthumously at the same rate as football.
"We're not nearly as far in hockey [research] as we are in football because we just don't have the same numbers," McKee said in a phone interview with ESPN.com.
Released in late July, McKee's study showed 177 of 202 deceased football players' brains had chronic traumatic encephalopathy -- commonly referred to as CTE. This included 110 of 111 brains of NFL players.
According to a Boston University CTE Center research assistant, neuropathology has been completed on just 16 hockey players' brains, nine of which were found to have CTE. All six of the NHL players' brains in the study had CTE. In total, 19 brains from hockey players have been donated to the center.
The Canadian Concussion Centre also has completed CTE studies on former NHLers, specifically those of Todd Ewen and Steve Montador. Ewen's brain did not have CTE, but Montador's did. The CCC said it wouldn't release its exact total for donated brains, but it said it has more than 30 and the majority of the donations are from football players.
"I think the guys are kind of recognizing the very simple but maybe courageous gesture of just kind of being able to donate the most important organ in your body could potentially benefit others down the road, be it through prevention, diagnosis or treatment or whatever the case may be," former NHL enforcer Stu Grimson said. "I think the awareness is really growing, but it's in its infancy."
Chronic traumatic encephalopathy is described by the BU study as a "progressive, degenerative disease of the brain found in athletes and others with a history of repetitive brain trauma." CTE can only be diagnosed posthumously. McKee's findings were published in the Journal of the American Medical Association
According to the website for Boston University's CTE Center, symptoms can include "memory loss, confusion, impaired judgment, impulse control problems, aggression, depression, suicidality, parkinsonism and eventually progressive dementia."
Hockey and football often have been linked to head injuries. Also, both the NFL and NHL have been involved in lawsuits with their former players over each league's handling of concussions. The NFL has settled its lawsuit; the NHL's is ongoing.
In her experience with hockey players, McKee said she has so far seen CTE but not to the same degree as in football players.
"It's not a systematic study, but just anecdotally looking at the players that have come into our brain bank compared to the football players, in general I think the hockey players have less CTE or a milder CTE. But again, this is based on very few numbers and this could change," she said. "But I haven't had the experience of seeing many, many advanced CTE cases in hockey like I have in football."
Although the level of CTE that McKee has seen in hockey isn't considered as severe, the effects of the disease can still have a damaging impact on a person's life.
"They can have very severe behavioral changes, like aggression, violence, impulsivity, disinhibition and even depression and hopelessness and suicidal behavior," McKee said. "That's what we're seeing in the individuals with mild CTE."
McKee noted that head hits are basically ingrained in football's fabric, while in hockey, they don't occur with the same frequency, which could in part be why her findings in hockey have been different. Still, that doesn't mean the sport is without both concussion and CTE risk.
NHL Alumni Association executive director and former goalie Glenn Healy, who just assumed his position this summer, said in his short time leading the alumni association, brain donation hasn't been a major topic among former players.
"I think it has been more prevalent in football, for instance, because you have 350-pound linemen who are facing off [against] each other and going full speed, and as they stop together, the brain keeps going. Our sport is different, and we do have our issues that we have to address, for sure; but in our circles, it hasn't been a prevalent conversation," he said. "I played 16 years, I worked with the NHLPA, and it's not a conversation I've had with any regularity."
An NHLPA spokesman declined to comment when asked about the difference between brain donation rates among hockey players versus football players.
The NHL so far has not accepted a link between head injuries and CTE, likely because it would influence its defense of the lawsuit by former players.
In 2015, NHL commissioner Gary Bettman said that "from a medical science standpoint" there was no evidence of a correlation between head injuries and CTE. In 2016, he noted that "playing hockey isn't the same as playing football," when asked about the NFL saying a link between CTE and football had been established.
The NHL has made changes to help curb concussion risks -- such as the creation of league's department of player safety, rule alterations to limit hits to the head and the introduction of concussion spotters in games -- but McKee thinks it shouldn't be too difficult to go further.
Last postseason, there was a debate over the term "hockey play," after those words were used to describe Washington Capitals defenseman Matt Niskanen's cross-check that concussed Pittsburgh Penguins superstar Sidney Crosby.
The belief is such plays that lead to head injuries shouldn't be up for debate, but there is still reluctance.
"These are extremely popular sports, and no one wants to make any changes because of their popularity," McKee said.
McKee stressed that the point of her research isn't to simply just diagnose CTE for shock value. It's to learn more about the disease in order to create treatments and make it less of a problem for people living with it. In order to do this, there needs to be more research across a wider variety of sports, which is why she wants more cognizance from the hockey community.
According to BU, knowledge of its research comes from word of mouth, and although they're well-known in the football community, it's not quite the same in hockey.
There's also the Concussion Legacy Foundation, which uses its connections in the sports community to raise awareness for brain donation with BU.
Founder Chris Nowinski told ESPN.com that former NHLers Keith Primeau, Shawn McEachern and Jeff Serowik have pledged their brains to his foundation but noted that the numbers in hockey simply don't add up to football players who want to donate.
Grimson, who said he has agreed to donate his brain posthumously, indicated that more proactive education on brain donation to players could help further awareness. At the moment, such information must be independently sought out and is not simply provided.
"Our alumni association or our players' association, I have not heard much from either entity -- from the NHL, for that matter -- I have not heard much from any of these entities just in terms of communication with former players," he said. "I think there's a lot to be gained if somebody was able to kind of get behind us and educate former players and current players about the benefits of donating, but I just haven't heard much in that regards."