(Reuters) - The National Football League's research into the dangers of head injuries undercounted diagnosed concussions, making them appear less frequent than they actually were, the New York Times reported on Thursday.
The newspaper, citing confidential data that it obtained, said an investigation showed the U.S. professional football league omitted more than 100 diagnosed concussions from studies the league commissioned from its teams, including severe injuries to stars like quarterbacks Steve Young and Troy Aikman.
NFL officials could not immediately be reached by Reuters for comment.
The Times said that when it asked the league about the missing cases - more than 10 percent of the total - officials acknowledged the teams were not required to submit their data and some did not.
The NFL told the newspaper the missing cases were not an attempt to alter the rate of concussions and that should have been made clearer.
Earlier this month for the first time a top NFL official acknowledged a link between football-related concussions and chronic traumatic encephalopathy (CTE), the degenerative brain condition caused by repeated blows to the head.
A group of retired players sued the NFL accusing the league of covering up the risks of concussions. They won a settlement that could cost the league up to $1 billion but some players have appealed the settlement.
The subject drew more attention from the 2015 film "Concussion," which starred Will Smith as a doctor who fought NFL efforts to conceal his research on brain damage suffered by players.
(Reporting by Ben Klayman; Editing by Jeffrey Benkoe)