The disclosure Friday comes in separate actuarial data the league and players' lawyers released as part of their proposed $765 million settlement of thousands of concussion lawsuits.
Both the league and lead players' lawyers expect about 6,000 of the 19,400 retired players, or 28 per cent, to develop Alzheimer's disease or at least moderate dementia. Dozens more will be diagnosed with Lou Gehrig's or Parkinson's disease during their lives, according to the data.
The reports were prepared for Senior U.S. District Judge Anita B. Brody, who is presiding over the class-action lawsuit in Philadelphia that accuses the NFL of hiding information that linked concussions to brain injuries.
The NFL report said the ex-players' diagnosis rates would be "materially higher than those expected in the general population" and would come at "notably younger ages."
The proposed settlement includes $675 million for player awards, $75 million for baseline assessments, $10 million for research and $5 million for public notice. It wouldn't cover current players.
Both sides have insisted that $675 million would be enough to cover awards for 21,000 former players, given fund earnings estimated at 4.5 per cent annually. Brody initially had concerns the money might run out, while critics complained the NFL's offering is a pittance given its $10 billion in annual revenues.
The NFL, in its report, said its estimates were "reasonable and conservative," and erred on the side of "overstating the number of players who will develop (illnesses)" to ensure the fund would be sufficient.
The league agreed this summer to remove the cap on its contributions, saying it would pay out more than $675 million if needed, and pay more over time if needed. Brody then granted preliminary approval of the plan and scheduled a fairness hearing on the proposed settlement for Nov. 19, when critics can challenge it.
"This report paints a startling picture of how prevalent neurocognitive diseases are among retired NFL players," lead player lawyers Christopher Seeger and Sol Weiss said in a statement.
Lawyers for some players have complained that the negotiations have been cloaked in secrecy, leaving them unsure of whether their clients should participate or opt out.
With an Oct. 14 deadline looming, "we still lack 'an informed understanding of the dynamics of the settlement discussions and negotiations.' Indeed, we have zippo understanding," lawyer Thomas A. Demetrio, who represents the family of Dave Duerson, wrote in a motion Thursday. Duerson, the popular Chicago Bears safety, committed suicide in 2011.
The family of former linebacker Junior Seau, who also committed suicide, has announced plans to opt out. He and Duerson are among about 60 former players diagnosed after their deaths with the brain decay known as chronic traumatic encephalopathy. Known as CTE, it can only be diagnosed after death.
Friday's release of the actuarial data was designed to address some of the complaints.
Critics also lament that the settlement plan offers no awards to anyone diagnosed with CTE in the future, and that the Alzheimer's and dementia awards are cut by 75 per cent for players who also suffered strokes.
The plan would pay up to $5 million for players with amyotrophic lateral sclerosis, also known as Lou Gehrig's disease; $4 million for deaths involving CTE; $3.5 million for Alzheimer's disease; and $3 million for moderate dementia and other neurocognitive problems.
However, only men under 45 who spent at least five years in the league would get those maximum payouts. The awards are reduced, on a sliding scale, if they played fewer years or were diagnosed later in life.
The players' data therefore predicts the average payouts, in today's dollars, to be $2.1 million for ALS, $1.4 million for a death involving CTE, and $190,000 for Alzheimer's disease or moderate dementia. The average ex-player being diagnosed with moderate dementia is expected to be 77 with four years in the NFL.
Only 60 per cent of those eligible for awards are expected to enter the program, based on prior class-action litigation. The payouts would top $900 million, adjusted for inflation.
The 21,000 class members also include the estates of 1,700 deceased players.