Former Cowboys Player Marshawn Kneeland Posthumously Diagnosed with Stage 1 CTE

Former Dallas Cowboys defensive end Marshawn Kneeland has been posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE). The diagnosis was confirmed by the Boston University CTE Center following the 24-year-old athlete's death by suicide in November 2025.

Neurological Condition Provides Context

The findings follow a history of documented mental health struggles dating back to 2020, including multiple hospitalizations and interventions by law enforcement. While the CTE diagnosis provides clinical context regarding the neurological condition of the athlete, researchers at the Boston University CTE Center emphasized that suicide is a complex, multifactorial event and should not be attributed solely to the presence of the disease.

Prevalence in Young Athletes

The case highlights ongoing concerns regarding the prevalence of neurodegenerative conditions in young contact-sport athletes. Dr. Ann McKee, director of the BU CTE Center, noted that the facility has identified signs of the progressive brain disease in nearly 50 percent of the athletes studied who died before the age of 30. The family stated that releasing the findings is intended to raise awareness regarding the challenges faced by athletes in high-contact sports.

This diagnosis continues to fuel discussions about player safety and long-term health in professional football.