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Ann McKee, director Boston University's center for research into the degenerative brain disease chronic traumatic encephalopathy, or CTE, addresses an audience on the school's campus Thursday, Nov. 9, 2017 about the study of NFL football player Aaron Hernandez's brain, projected on a screen, behind right, in Boston. McKee says Hernandez suffered severe damage to parts of the brain that play an important role in memory, impulse control and behavior. The cross section of the brain projected behind left is labeled a normal 27 year old.

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Doctor: Aaron Hernandez’s brain was severely damaged by disease

BOSTON — Former New England Patriots player Aaron Hernandez suffered substantial damage to parts of the brain that affect memory, judgment and behavior from the most severe case of a degenerative disease linked to head blows ever found in someone so young, a researcher said Thursday.