BOCA RATON, Fla. - Two days after the National Football League became the first professional sports league to acknowledge medical research linking on-field head trauma and chronic traumatic encephalopathy (CTE), NHL commissioner Gary Bettman declined to comment on the development.

“Well, first of all, I don’t feel that it’s either necessary or appropriate for me to comment on what the NFL says or does,” Bettman said Wednesday. “Secondly, I think it’s fairly clear that playing hockey isn’t the same as football. And as we’ve said all along, we’re not going to get into a public debate on this.”

The NHL has previously maintained that concussion research does not conclusively link head trauma to the degenerative brain disease.

“From a medical science standpoint, there is no evidence yet that one necessarily leads to the other,” Bettman told reporters last May. “I know there are a lot of theories, but if you ask people who study it, they tell you there is no statistical correlation that can definitively make that conclusion.”

More than 100 former NHL players have filed suit against the league over concussions, alleging that they were not made aware of the potential risk or properly treated for head trauma.

On Monday, the NFL’s senior vice president for health and safety, Jeff Miller, acknowledged the link to CTE, which can only be diagnosed after death and can lead to early onset dementia, Alzheimer’s disease and other neurodegenerative disorders.

According to ESPN.com, Miller was asked in a U.S. House of Representatives roundtable discussion on concussions whether research by Boston University neuropathologist Ann McKee has established a firm link between football and CTE.

“The answer to that question is certainly yes,” Miller said, according to ESPN.com.

Concussion researchers celebrated Miller’s statement as a victory and form of recognition from the NFL and other powerful sports leagues that has long been ignored. The NFL had never stated in any official capacity that CTE is a potential lasting effect from concussions.

In 2013, the NFL reached a settlement to provide $765 million in medical assistance to more than 4,500 former players.

The ongoing lawsuit between the NHL and its former players could take years to play out in court.

“This commissioner and our owners have always respected the contributions of our former players and have continually taken steps to improve their post-career benefits and opportunities," NHL deputy commissioner Bill Daly recently told ESPN.com. “But we take great issue with any contention that the league did not at all times give appropriate attention to the health and safety of our players or that we did anything inappropriate or wrong. We fully intend to establish those facts through the judicial process.”

Contact Frank Seravalli on Twitter: @frank_seravalli