Researchers confirm stage 1 CTE in late Cowboys defensive end Marshawn Kneeland

The family of former Dallas Cowboys defensive end Marshawn Kneeland announced that researchers diagnosed him with stage 1 chronic traumatic encephalopathy (CTE) after a post-mortem analysis of his brain tissue. Kneeland died by suicide in November, and the reporting around the findings includes discussion of suicide, so support resources are important. In the United States, call or text 988, or chat for immediate help; if you are outside the U.S., the equivalent local crisis hotline is recommended.

According to the announcement relayed by media reports, the diagnosis was made by Boston University CTE Center researchers as part of work done through the Concussion & CTE Foundation. CTE can only be confirmed by examining brain tissue after death, and the stage 1 label is presented as the earliest form in the disease process, rather than a measure of severity at the end of life.

CTE is often discussed in terms of repeated head impacts rather than only concussions. In the statements attributed to Boston University’s Dr. Ann McKee, the director of the BU CTE Center and chief of neuropathology for the VA Boston Healthcare System said she was not surprised to find CTE in Kneeland’s brain because the condition has been identified in nearly half of athletes she and her team have studied who died before age 30. That framing emphasizes that the disease is not rare among young athletes studied post-mortem.

Chris Nowinski, the CEO of the Concussion & CTE Foundation, was also quoted in connection with the findings. He said Kneeland played in the modern era with concussion protocols and improved helmets, yet still developed CTE. Nowinski added that there is no reason to believe today’s generation is at lower risk than previous ones, and he argued that concussion protocols do not prevent CTE because CTE is driven by repeated head impacts, not just the occurrence of diagnosed concussions.

Stage 1 CTE, as described by organizations referenced in the coverage, may be associated with short-term memory issues, depression, aggression, explosivity, and executive-function problems. Researchers also emphasized that, while a diagnosis does not change the tragedy of a player’s death, it can provide context about struggles that may have existed in life. The announcement therefore sits at the intersection of sports medicine, mental health, and the long debate about how the game can reduce brain-risk exposure at every level.

Kneeland entered the NFL as a young player, drafted by Dallas in the second round of the 2024 NFL Draft. The reports state he appeared in 18 games with the Cowboys. His time in the league coincided with the league’s current approach to concussion identification and return-to-play rules, making the discussion about “modern era” equipment and protocols central to the message being drawn from the case.

The Cowboys’ role in this story is chiefly historical and informational at this point. The diagnosis was released through the family’s announcement and the foundation’s communications, rather than through the NFL or Dallas directly in the material being cited. For fans and evaluators, what matters is how another early-stage CTE finding continues to shape conversations about contact management, tackling technique, youth football practices, and how teams measure and mitigate head-impact loads.