Former NFL quarterback Earl Morrall was found to have Stage 4 CTE in his brain at the time of his death in 2014.

Former NFL quarterback Earl Morrall was found to have Stage 4 CTE (chronic traumatic encephalopathy), when he died in April 2014 at age 79, his family toldThe New York Times.

CTE, which is measured on a scale from one to four,​ has been linked with repeated head trauma, such as the blows delivered in football. The disease can cause memory loss and depression, among other symptoms. Boston University has now found CTE in 90 of the 94 former NFL players it has studied, seven of which were quarterbacks.

When Morrall died in 2014, his family said it was due to complications from Parkinson’s disease​.

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Morrall had an All-American career at Michigan State and went on to play 21 seasons in the NFL after being drafted second overall in 1956 by the San Francisco 49ers. He stepped in for an injured Johnny Unitas at quarterback and led the Baltimore Colts to a 13–1 record and Super Bowl III victory in 1968. He also started 11 games during the Dolphins' perfect season in 1972 as he filled in for Bob Griese. Morrall also spent time with the Steelers, Lions, and Giants in his career.

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The New York Timesalso revealed that former Raiders quarterback Ken Stabler had stage three C.T.E. in his brain, when he died at 69 last July.