Risk of chronic traumatic encephalopathy in rugby union is associated with length of playing career.

"Declarations Conflict of interestThe authors declare no competing interests. Ethics approvalThe Glasgow TBI Archive has specific Research Ethics Committee approval as a Research Tissue Bank (ref 22/WS/0168). The Australian Sports Brain Bank has ethical approval granted by the Sydney Local Health District Human Research Ethics Committee, Royal Prince Alfred Hospital (ref: X23-0073). Conflict of interest The authors declare no competing interests."

"This work is supported by funding from: the National Institute of Neurological Disorders and Stroke of the National Institutes of Health (Award Nos. R01NS092398, R01NS094003, R01NS038104, U54NS115322, U01NS086659, U01NS093334, U54NS115266, R01NS078337, and R56NS078337); National Institute on Aging (Award Nos. AG057902, AG06348 and supplement 0572063345); US Department of Veterans Affairs (CX00135 to Dr. McKee and CX001038 to Dr. Stein); The Concussion Legacy Foundation; The Andlinger Foundation; and an NHS Research Scotland Career Researcher Fellowship (WS). The ASBB is supported by Sydney Local Health District and unrestricted philanthropic donations."