Boston University’s CTE Center diagnosed former Dallas Cowboys defensive end Marshawn Kneeland with chronic traumatic encephalopathy, better known as CTE.
Kneeland, who died by suicide in November 2025 at 24 years old, had Stage 1 CTE, according to the center.
“Unfortunately, I was not surprised to find CTE in the brain of Mr. Kneeland, because we have found this progressive brain disease in nearly half of the athletes we’ve studied who have died before the age of 30,” Dr. Ann McKee, director of the Boston University CTE Center and chief of neuropathology for the VA Boston Healthcare System, said in a prepared statement.
Kneeland was in the middle of his second season before his death on Nov. 6, 2025. He is part of a growing list of former players that have been diagnosed with CTE.
What is CTE?
CTE is a degenerative brain disease that destroys nerve cells in the brain and is caused by accumulated blows to the head.
The disease can only be found after death by studying the brain. It has commonly been found in former athletes of high-contact sports such as football and boxing, as well as in military combat veterans and first responders.
According to the Boston center, CTE is not limited to current professional athletes; it has also been found in athletes who did not play sports after high school or college. Nearly all young athletes had mild CTE, the center said. The stages range from one to four, with four being most severe.
Those with CTE can have several symptoms, such as memory loss, confusion, impaired judgment, lack of impulse control, aggression, depression and even suicidal tendencies.
How many former players have been diagnosed?
In a study conducted by Mass General Brigham researchers in 2024 of nearly 2,000 former NFL players, about one-third believe they have CTE.
Scores of athletes have been diagnosed, including Canton brothers John and Ed Grimsley.
Boston’s CTE Center in 2023 said that out of 376 former players studied, 91.7% were posthumously diagnosed with CTE.
NFL players 4 times more likely to die of neurodegenerative disease, study finds
NFL players are nearly four times more likely to die of neurodegenerative diseases such as ALS, Parkinson’s or dementia than the general population, according to a new study from Mass General Brigham, Boston University and the Concussion & CTE Foundation.
The study, published in eClinicalMedicine on July 8, reviewed health data from 19,824 players who played in at least one professional football game between 1960 and 2019. Overall, the group had a lower all-cause mortality rate compared to the general population. That is not the same in neurodegenerative mortality, with dementia (3.8-times higher) and Parkinson’s (3.88-times higher) presenting greater risk for NFL players.
Players with longer careers – considered five seasons or more – had double the risk of neurodegenerative death compared to those who played four seasons or less.
Who are some former football players diagnosed with CTE?
Some notable football players diagnosed with CTE include:
Includes reporting by USA TODAY staff writer Chris Bumbaca.
This article originally appeared on The Repository: Marshawn Kneeland, former Cowboys player, diagnosed with CTE after death
Reporting by Aaron Hughes, Canton Repository / The Repository
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By Aaron Hughes, Canton Repository | USA TODAY Network
