Tests to determine CTE in the living are still years away.
By 2014, the NIH had identified 59 cases of CTE in 62 ex-players' brains they had studied.
Among the players found to have CTE in their brains were Hall of Famers Junior Seau and Ken Stabler.
"Certainly based on Dr McKee's research, there's a link, because she's found CTE in a number of retired football players.
Especially influential was the first diagnosis of CTE in an American football player, Mike Webster, in the early 2000s.
A spate of deaths of former players revealed chronic traumatic encephalopathy (CTE) in their brains, the result of repeated head injuries.
Directed by Peter Landesman (Parkland), Concussion centers on Dr Bennet Omalu Smithh), the Nigerian forensic pathologist and neuropathologist who discovered chronic traumatic encephalopathy (CTE) in football players, who take countless blows to the head playing the sport.
In the first of Monday's objections, the 10 retirees said "no settlement at all" was better than one offering nothing for the "vast majority" of former players, who "will probably die with evidence of CTE in their brains".
Dr Julian Bailes, another pioneer in the battle to expose CTE in the NFL, believes that the former Pittsburgh Steelers centre Mike Webster took around 100,000 such hits when he played American football.
Concussion, the first trailer for which hit the web on Monday, stars Smith as Dr Bennet Omalu, the Nigerian-born forensic pathologist and neuropathologist who discovered chronic traumatic encephalopathy (CTE) in American football players.
Back in 2012 researchers at UCLA developed an imaging tool which can identify a buildup of an abnormal protein called tau in the brain – which, in a distinct form, identifies CTE – in people still alive.
