Dallas Cowboys player who died by suicide diagnosed with brain disease
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- Marshawn Kneeland, a Dallas Cowboys defensive lineman, was diagnosed with stage 1 CTE through postmortem brain tissue analysis by Boston University's CTE Center after dying by suicide in November 2025 at age 24.
- Dr. Ann McKee, director of BU's CTE Center, said she was "not surprised," noting CTE has been found in nearly half of athletes studied at the center who died before age 30.
- Kneeland's family said the diagnosis provides "important context" about his struggles and shared the findings publicly to help people understand what NFL and high-contact sport athletes may endure.
- Dr. Chris Nowinski, co-founder and CEO of the Concussion & CTE Foundation, said Kneeland "played in the modern era of concussion protocols and better helmets, and yet he still developed CTE," arguing current athletes face no lower risk than previous generations.
- BU's CTE Center clarified that CTE can only be diagnosed after death and that a postmortem CTE diagnosis is not known to be a risk factor for suicide, calling the cause of suicide "complex."
- Kneeland was drafted by the Cowboys in the second round of the 2024 NFL Draft, played 18 games with four starts, began tackle football at age 7, and starred at Western Michigan University before joining Dallas as a defensive end.
Why it matters: For the NFL and youth tackle football programs, a stage 1 CTE diagnosis in a 24-year-old who played entirely under current safety standards directly challenges the league's investment in modern concussion protocols and helmet technology. Dr. Chris Nowinski's explicit framing — that today's athletes face no lower CTE risk than previous generations — intensifies pressure on leagues and governing bodies to develop new preventive measures.
