Dallas Cowboys Lineman Diagnosed With CTE

Post-mortem analysis confirms early-stage brain disease

Researchers at the Boston University CTE Center confirmed that Dallas Cowboys defensive lineman Marshawn Kneeland was diagnosed with stage 1 chronic traumatic encephalopathy following his death by suicide in November 2025 at age 24. The findings, released by the Concussion and CTE Foundation, represent the lowest level of the neurodegenerative condition on a four-stage clinical scale.

The mechanism of CTE involves the accumulation of abnormal tau protein in the brain, which is linked to repetitive head impacts sustained during contact sports. While the condition remains detectable only through post-mortem tissue analysis, the prevalence of the disease among young athletes is increasing. Data from the Boston University CTE Center indicates that nearly 50 percent of athletes studied who died before age 30 exhibited signs of the disease.

This diagnosis underscores the ongoing medical challenge of identifying neurodegenerative markers in living patients. Current research efforts are focused on developing diagnostic tools to detect the disease during a patient's lifetime, though no clinical cure currently exists. The findings contribute to a growing body of evidence regarding the long-term neurological risks associated with professional football participation.