Former Dallas Cowboys defensive end Marshawn Kneeland has been posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE), his family announced, shedding light on the potential struggles faced by young athletes.
Kneeland died by suicide on November 6, 2025, at the age of 24.
The diagnosis, confirmed by Boston University’s CTE Center following a brain tissue analysis performed by the Concussion & CTE Foundation, revealed Stage 1 CTE, the lowest of four levels. This degenerative brain disease can only be definitively identified through post-mortem examination of brain tissue.
Dr. Ann McKee, director of the Boston University CTE Center and chief of neuropathology for the VA Boston Healthcare System, expressed that the finding was not unexpected.
“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,” she stated. Dr. McKee added that understanding these early stages is crucial for future diagnosis and treatment, noting, “My team and I are fully dedicated to finding effective treatments and a cure for CTE.”
Kneeland’s family, including his girlfriend Catalina Mancera, released a statement on Tuesday, emphasizing the significance of the diagnosis.
“While this diagnosis does not change the tragedy of his passing, it provides important context about some of the struggles he may have been facing,” the statement read.
They shared the information to “help people understand what NFL and other high contact sport athletes might be struggling with,” and to raise awareness, remembering Marshawn “with compassion for the person he was, rather than defining him by the final moments of his life. One Love.”
Authorities reported that Texas police attempted to stop Kneeland’s vehicle, leading to a chase. He crashed, fled on foot, and was later found deceased.
A second-round draft pick for the Cowboys in 2024, Kneeland played seven games last season, notably recovering a loose ball and scoring his first career touchdown on November 3 in a 27-17 loss to the Arizona Cardinals.
If you are experiencing feelings of distress, or are struggling to cope, you can speak to the Samaritans, in confidence, on 116 123 (UK and ROI), or visit the Samaritans website to find details of your nearest branch.
If you are based in the USA, and you or someone you know needs mental health assistance right now, call or text 988, or visit 988lifeline.org to access online chat from the 988 Suicide and Crisis Lifeline. This is a free, confidential crisis hotline that is available to everyone 24 hours a day, seven days a week. If you are in another country, you can go to www.befrienders.org to find a helpline near you.
