BOSTON -- Aaron Hernandez suffered the most severe case of chronic traumatic encephalopathy ever discovered in a person his age, damage that would have significantly affected his decision-making, judgment and cognition, researchers at Boston University revealed at a medical conference Thursday.
Dr. Anne McKee, the head of BU's CTE Center, which has studied the disease caused by repeated brain injury for more than decade, called Hernandez's brain "one of the most significant contributions to our work" because of the brain's pristine condition and the opportunity to study the disease in a 27-year-old brain.
Hernandez, a former New England Patriots tight end, committed suicide in April in a Massachusetts prison while serving a life sentence for the murder of his friend Odin Lloyd in 2013. Hernandez hanged himself with a bedsheet.
Doctors diagnosed Hernandez with Stage 3 CTE, which researchers had never seen in a brain younger than 46 years old, McKee said. His brain had significant damage to the front lobe, which impacts a person's ability to make decisions and moderate behavior.
At the conference Thursday, McKee flipped through slides comparing sections of Hernandez's brain to a sample without CTE. Hernandez's brain had dark spots associated with tau protein and shrunken, withered areas, compared to pristine white of the sample. As some new slides appeared on the projectors, some physicians and conference attendees gasped.
"We can't take the pathology and explain the behavior," McKee said. "But we can say collectively, in our collective experience, that individuals with CTE, and CTE of this severity, have difficulty with impulse control, decision-making, inhibition of impulses for aggression, emotional volatility, rage behaviors. We know that collectively."
Boston University has received few brains to study from people Hernandez's age, so McKee could not say whether Hernandez's brain was representative of a 27-year-old who had played football as much as Hernandez, a high school star in Connecticut and a collegiate standout at Florida. But she found the advanced stage of CTE in Hernandez's brain alarming.
"In this age group, he's clearly at the severe end of the spectrum," McKee said. "There is a concern that we're seeing accelerated disease in young athletes. Whether or not that's because they're playing more aggressively or if they're starting at younger ages, we don't know. But we are seeing ravages of this disease, in this specific example, of a young person."
McKee said Hernandez had a genetic marker that makes people vulnerable to certain brain diseases.
"We know that that's a risk factor for neurogenerative disease," McKee said. "Whether or not that contributed in this case is speculative. It may explain some of his susceptibility to this disease."
BU researchers say they have discovered CTE in more than 100 former NFL players, a handful of whom have committed suicide.
The findings represent another marker in the football's ongoing concussion crisis, as the NFL is also trying to untangle strife in the wake of players protesting during the national anthem, which has drawn the ire of President Donald Trump and potentially rattled the status of Commissioner Roger Goodell.
Researchers had previously disclosed severe signs of CTE in Hernandez's brain, indicating his brain had degenerated to a degree typically associated with a person in his late 60s. Jose Baez, a lawyer for Hernandez's family, said it was "the most severe case they had ever seen in someone of Aaron's age."
Hernandez's estate filed a federal lawsuit against the Patriots in September, alleging the Patriots knew hits to the head could lead to brain and failed to protect him.