This article is more than 2 years old

This article is more than 2 years old

Former New England Patriots player Aaron Hernandez suffered severe damage to parts of the brain that play an important role in memory, impulse control and behavior, a researcher who studied his brain said Thursday.

Dr Ann McKee, director of the CTE Center at Boston University, said she could not “connect the dots” between Hernandez’s severe case of chronic traumatic encephalopathy, which is linked to repeated blows to the head, and his behavior. The 27-year-old hanged himself in April, while serving life in prison for murder.

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But McKee said Hernandez experienced substantial damage to key parts of the brain, including the hippocampus which is important to memory and the frontal lobe, which is involved in problem solving, judgment and behavior.

“In any individual we can’t take the pathology and explain the behavior,” said McKee, who has studied hundreds of brains from football players, college athletes and even younger players, donated after their deaths. “But we can say collectively, in our collective experience, individuals with CTE and CTE of this severity have difficulty with impulse control, decision-making, inhibition of impulses or aggression, often emotional volatility and rage behaviors,” she said.

Hernandez hanged himself in prison days after he was acquitted in the 2012 drive-by shootings of two men in Boston and just hours before his former teammates visited the White House to celebrate their latest Super Bowl victory.

Facebook Twitter Pinterest Dr Ann McKee presented images of Aaron Hernandez’s brain on Thursday that showed the worst case of CTE ever found in someone his age. Photograph: Ann McKee, MD, BU CTE Center/VA Boston

Facebook Twitter Pinterest McKee said Hernandez experienced damage to key parts of the brain, including the hippocampus which is important to memory and the frontal lobe, which is involved in problem solving, judgment and behavior. Photograph: Ann McKee, MD, BU CTE Center/VA Boston

Prosecutors claimed he gunned the two men down after one accidentally spilled a drink on him in a nightclub and then got a tattoo of a handgun and the words “God Forgives” to commemorate the crime.

He had been serving a life sentence without parole in the 2013 killing of semi-professional football player Odin Lloyd when he killed himself in April.

Hernandez, who said he was innocent, did not raise CTE in his defense at either trial.

But after his death and September CTE diagnosis, his attorneys filed a lawsuit against the NFL and football helmet maker Riddell, accusing them of failing to warn Hernandez about the dangers of football. The lawsuit, which seeks damages for Hernandez’s young daughter, said he experienced a “chaotic and horrendous existence” because of his disease.

Hernandez inherited a genetic profile that may have made him more susceptible to developing the disease, McKee said. She said Hernandez had the most severe case of CTE they’ve seen in someone his age.

Facebook Twitter Pinterest McKee, director of the CTE Center at Boston University, can not draw a line between Hernandez’s severe case of CTE and the behavior that led to his conviction in a 2013 homicide. Photograph: Ann McKee, MD, BU CTE Center/VA Boston

Facebook Twitter Pinterest McKee also said Hernandez inherited a genetic profile that may have made him more susceptible to developing the disease. Photograph: Ann McKee, MD, BU CTE Center/VA Boston

Hernandez was diagnosed with Stage 3, out of 4, of the disease.

While the outside of Hernandez’s brain appeared normal, the inside showed evidence of previous small hemorrhages, which experts associate with head impacts. Other parts of his brain had begun to shrink and show large holes in the membrane, McKee said.

“Individuals with similar gross findings at autopsy were at least 46 years old at the time of death,” McKee said.