Former Cowboys Lineman Marshawn Kneeland Had Stage 1 CTE

Former Dallas Cowboys defensive lineman Marshawn Kneeland was diagnosed with stage 1chronic traumatic encephalopathy (CTE).

Kneeland's family announced the Boston University CTE Center's diagnosis through the Concussion & CTE Foundation on Tuesday. They requested a post-mortem brain tissue analysis after Kneeland died by suicide at age 24 in November 2025.

"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."

"Raising awareness is important to us"

Kneeland's family, including his girlfriend Catalina Mancera, released a statement.

"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."

Dr. Chris Nowinski, Concussion & CTE Foundation CEO, called for more measures to mitigate head trauma in NFL games. The Concussion & CTE Foundation also noted that CTE "should not be considered the cause of a suicide and is not known to be a risk factor for suicide."

"Mr. Kneeland played in the modern era of concussion protocols and better helmets, and yet he still developed CTE," Nowinski said. "We have no reason to believe the current generation is at a lower risk of CTE than previous generations. 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."