Former Dallas Cowboys defensive end Marshawn Kneeland has been posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE). Kneeland died by suicide in November 2025 at the age of 24. His family donated his brain to Boston University's CTE Center, which confirmed the diagnosis.

Kneeland's family released a statement acknowledging the diagnosis provides context for his struggles, aiming to raise awareness for athletes in high-contact sports. They stressed that CTE is complex and should not be considered the sole cause of suicide.

Records indicate mental health concerns for Kneeland dated back to 2020, including incidents requiring counseling and police intervention due to suicidal ideations. His death involved a high-speed pursuit by Texas police prior to him evading officers and crashing his vehicle.

Dr. Ann McKee of BU's CTE Center noted that the disease has been found in nearly half of athletes studied who died before 30, underscoring the ongoing research into early diagnosis and treatment.