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Former Chicago Bears defensive tackle Steve McMichael has been diagnosed with Stage 3 (of 4) chronic traumatic encephalopathy, according to the Concussion & CTE Foundation.

McMichael, who died last year at age 67 following a five-year battle with amyotrophic lateral sclerosis (ALS), was part of the Bears’ 1985 Super Bowl-winning team and was inducted into the Pro Football Hall of Fame in 2024.

A degenerative brain disease, CTE has often been found in those who played contact sports, such as football, and others who have experience repetitive head trauma. It’s known to cause cognitive decline, depression and violent mood swings. It can only be diagnosed after death.

While he was still alive, McMichael pledged to donate his brain.

“By sharing Steve’s diagnosis, we want to raise awareness of the clear connection between CTE and ALS,” said McMichael’s wife, Misty, in a statement. “Too many NFL players are developing ALS during life and diagnosed with CTE after death. I donated Steve’s brain to inspire new research into the link between them.”

NFL players are more than four times more likely to develop ALS compared to the general male population, according to a 2021 study led by Harvard Medical School and the Boston University CTE Center researchers.

McMichael, who was also known as Mongo, was a five-time All-Pro who played 13 of his 15 NFL seasons for the Bears. He was a key member as a first-team All-Pro for the famed 1985 Bears defense that anchored the franchise's only run to a Super Bowl championship.