Former Cowboys defensive lineman Marshawn Kneeland had the earliest stage of a degenerative brain disease, chronic traumatic encephalopathy (CTE), according to researchers at Boston University’s CTE Center.
Kneeland, who died in November of 2025 at 24, had stage 1 CTE. According to the research, the earliest stage of the brain disease associated with head trauma in contact sports may be connected to difficulties with attention, concentration, and headaches.
Nearly 50% of players under age 30 studied by researchers have shown CTE, according to the study’s lead investigator.
Researchers say the family of former Dallas Cowboys player has hope that sharing Kneeland’s case can raise awareness. The findings in Kneeland, an early-round pick of the Cowboys out of Western Michigan University, come in a league struggling with the head-trauma consequences on former players.
The former second-round draft pick played 18 games for the Cowboys since starting football as a 7-year-old kid and has a playing history before his football journey.
New CTE research on a former Cowboys player raises concerns among players. Researchers said more steps are needed to prevent CTE among athletes.
