Dave Mirra, the star BMX rider who killed himself in February, had C.T.E., chronic traumatic encephalopathy, the brain disease linked to head trauma.
The condition was diagnosed by neuropathologists at the University of Toronto and the Canadian Concussion Center, where Mirra’s brain was examined after his death.
“It’s assumed it is related to multiple concussions that happened years before,” Dr. Lili-Naz Hazrati told ESPN.
Mirra won 14 gold medals at the X Games and helped popularize freestyle BMX, in which riders perform tricks on bicycles on the ground and soaring through the air. In 2000, he became the first person to land a double back flip in a competition.