The tragic story of former Dallas Cowboys defensive lineman Marshawn Kneeland has taken a heartbreaking new turn. Researchers at the Boston University CTE Center confirmed that Kneeland had stage 1 chronic traumatic encephalopathy (CTE)—the earliest stage of the degenerative brain disease linked to repeated head impacts. He was only 24 years old when he died by suicide in November 2025.
Kneeland’s family, alongside the Concussion & CTE Foundation, released the findings Tuesday. They had requested a post-mortem brain tissue analysis to better understand what he may have been going through. The diagnosis, while devastating, offers some clarity about the challenges he faced in his final months.
“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 Boston University CTE Center and chief of neuropathology for the VA Boston Healthcare System. “Thanks to the generosity of our brain donor families, we now better understand the earliest stages of CTE, and it is bringing us closer than ever to diagnosing it during life. My team and I are fully dedicated to finding effective treatments and a cure for CTE.”
Kneeland’s loved ones, including his girlfriend Catalina Mancera, shared a statement emphasizing that this diagnosis doesn’t define his life but helps explain some of the invisible battles he fought. “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 family said. “We share this information to help people understand what NFL and other high contact sport athletes might be struggling with. Raising awareness is important to us. We continue to remember Marshawn with compassion for the person he was, rather than defining him by the final moments of his life. One Love.”
The findings have sparked renewed calls for change. Dr. Chris Nowinski, CEO of the Concussion & CTE Foundation, pointed out that Kneeland played in an era with advanced concussion protocols and better helmets—yet still developed CTE. “We have no reason to believe the current generation is at a lower risk of CTE than previous generations,” Nowinski said. “Concussion protocols do not prevent CTE, because CTE is caused by repeated head impacts, not just concussions. If we want to reduce CTE risk, we must implement CTE prevention protocols and aggressively reduce the number and strength of head impacts at every level of the game.”
Kneeland’s case echoes the broader concerns about head trauma in football, which have led many former players to advocate for safer practices. Some, like 128 former NFL pros now coaching high school football, are working to change the culture from the ground up. Others, like former 2,000-yard rusher Chris Johnson, have spoken out about their own battles with ALS—another cruel neurological disease that has cut short the lives of athletes.
The Concussion & CTE Foundation stressed that CTE should not be considered the cause of a suicide and is not known to be a risk factor for suicide. Still, the diagnosis underscores the urgent need for better detection and prevention. As Dr. McKee noted, research into the earliest stages of CTE is bringing scientists closer than ever to diagnosing it during life—a breakthrough that could save countless athletes from suffering in silence.
Kneeland’s family hopes that by sharing his story, they can help others understand the hidden price of playing high-contact sports. “One Love,” they said—a reminder that behind every statistic and every diagnosis, there was a young man who loved the game and left it too soon.
