At least one in four former NFL players who died in 2016-21 had CTE

At least 215 of the 878 former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy, or 24.5 percent of every man who had played in the league and then died in those six years. That is the floor, not the estimate.

Researchers at Mass General Brigham, Boston University and the Concussion and CTE Foundation published the figures in The BMJ. They started with every former NFL player who died in the window, 878 people, ages from the 20s to the 80s. Families donated 235 of those brains. Neuropathologists found CTE in 215. The remaining 643 brains were never examined. If even a fraction of them also had the disease, the true share sits well above one in four. The authors wrote that the possible range runs from 24.5 percent to 97.7 percent.

CTE can be diagnosed only after death, by looking at tissue. In the general population the rate at death is under 1 percent. Dr. Daniel Daneshvar, who treats former players with dementia at Mass General Brigham, called the 25 percent floor a wake-up call and said money should move toward treatment and a cure. Among 315 donors across a wider period whose tissue showed CTE, clinicians found dementia in 61.3 percent. At Stage IV that share was 90.4 percent. About 60 percent of people with CTE in the study could not feed or groom themselves by the end.

A longer ledger, 1,712 former players who died between 2008 and 2021, produced 338 donated brains and CTE in 315 of them, or 93.2 percent of the donated set. The authors preferred the 2016-2021 slice because donations in those years better matched the full list of deaths, which reduces the bias that comes when only the most damaged families donate.

Apply the floor to a 53-man roster and at least 13 players would be expected to develop the pathology. Apply it to the 1,696 men on 32 opening-day active rosters and the floor is about 400. Practice-squad and injured-reserve names sit outside that count.

The NFL Players Association called the paper a call to action. The league has spent two decades adding helmet rules, concussion protocols and Guardian caps at practice. Those steps cut some observable hits. They do not erase the thousands of sub-concussive contacts that define a season. CTE tracks cumulative impact, not only the hits that trigger a sideline exam.

What the study does not do is tell a living player whether he has the disease. There is still no validated scan that replaces an autopsy. Families donate because they watched a husband or father lose memory, mood and motor control and wanted a name for it. That selection effect is why the authors refused a single percentage and published a range instead.

The useful number for clubs, unions and parents of high-school linemen is the floor. One in four is already higher than the rate most sports use to describe rare neurological risk. The ceiling in the same paper is almost every donated brain. Policy that pretends the risk lives only at the extreme end of a career now has to argue with 215 confirmed cases out of 878 deaths.

Ann McKee’s laboratory at Boston University has been the main address for these brains for years. The new paper’s contribution is not another famous name on a slide. It is a denominator: every former NFL player who died in a defined window, not only the men whose families already suspected CTE. That is why 24.5 percent landed harder than the older figures drawn from donated samples alone.

High-school and college programmes now have to read the same floor. Most of those athletes will never reach an NFL locker room. They still take the same class of hits in a smaller helmet. The study does not measure them. It measures the men who lasted long enough to be paid for it, and still came in at one in four.

Daneshvar’s clinic will keep seeing the men who can still walk through the door. The 215 cannot. Their tissue is the data. The argument left is how many of the 643 unknown brains would have looked the same under a microscope, and what a league does with a minimum rate of 25 percent.