Dallas Cowboys player who died by suicide diagnosed with brain disease
NFL player Marshawn Kneeland was found to have stage 1 chronic traumatic encephalopathy (CTE) at the time of his death by suicide last year, according to scientists.
Researchers at Boston University's CTE Center confirmed the diagnosis through a postmortem analysis of the brain tissue of the Dallas Cowboys defensive lineman, who died at age 24.
"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," said Dr Ann McKee, director of the centre.
Stage 1 is the mildest of CTE's four stages, with common symptoms including headaches and difficulties with attention or concentration.
In a statement, Kneeland's family said the diagnosis offered "important context" regarding some of the challenges he faced.
"We information to help people understand what NFL and other high-contact sport athletes might be struggling with," they said. "We continue to remember Marshawn with compassion for the person he was, rather than defining him by the final moments of his life."
Kneeland died in November 2025 following a car chase involving Texas State Troopers, who attempted to stop him for a traffic violation. Police reported that he crashed his vehicle and fled on foot. He was later discovered deceased from a self-inflicted gunshot wound during the early morning hours.
Kneeland was drafted by the Cowboys in the second round of the 2024 NFL Draft and appeared in 18 games for the team, including four starts. He began playing tackle football at age seven and was a member of Western Michigan University's football team before joining the Cowboys as a defensive end.
What is CTE?
Research indicates that athletes participating in American football, rugby, and combat sports have a significantly elevated risk of developing CTE compared to the general population.
CTE can only be definitively diagnosed postmortem. The disease, caused by repeated head trauma, has been identified in the brains of hundreds of former NFL players.
In 2023, Boston University's CTE Center reported diagnosing CTE in 345 of the 376 former NFL players it had examined.
The NFL has agreed to a $1 billion (£700 million) settlement following a lawsuit filed by more than 5,000 former players. Over 21,000 ex-players may be eligible for compensation.
During stage 1 of CTE, individuals may experience short-term memory issues, depression, aggressive behavior, and difficulties with executive functions, according to the CTE Society, a non-profit organization.
As the disease progresses, these symptoms intensify and additional problems such as mood swings and suicidal thoughts may develop.
In the final stage, severe cognitive impairment, memory loss, and dementia can occur, as noted by the CTE Society.
Boston University's CTE Center emphasized that suicide causes are complex and that a postmortem CTE diagnosis is not established as a suicide risk factor.
However, CTE researchers stated that Kneeland's case highlights insufficient measures taken to reduce the disease risk among athletes.
"Mr Kneeland played in the modern era of concussion protocols and better helmets, and yet he still developed CTE," said Dr Chris Nowinski, co-founder and CEO of the Concussion & CTE Foundation.
"We have no reason to believe the current generation is at a lower risk of CTE than previous generations."
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