Miller also said several questions need to be asked on the subject, and players took to social media to air their response.
Chris Kluwe, a former punter for the Minnesota Vikings, mocked the NFL's concession in a tweet.
"NFL also admits 'water likely wet,' as well as 'sky possibly blue on occasion,"' Kluwe (@ChrisWarcraft) tweeted yesterday.
A tweet sent from Cleveland Browns wide receiver Brian Hartline's Twitter account cited the Boston University data. "Boston University researchers have found evidence of CTE in 90 of 94 former NFL players studied," Hartline tweeted.
"Ya there's a link."
Player safety has long been a topic of concern in the league but focus intensified over brain injury last year.
The 2015 film Concussion, as well as the August 2015 posthumous induction of linebacker Junior Seau into the Pro Football Hall of Fame, brought more attention to the issue.
Seau committed suicide in 2012 and a study of his brain later showed he had CTE.
Ravens' tackle Eugene Monroe (@The SeventyFifth) also tweeted a link to an article about Miller's testimony.
Later, he tweeted: "If you're a player and you see this. Junior Seau and many others. Yes, it can be us too."