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Aaron Hernandez, a former New England Patriot and convicted murderer who died from suicide in jail in April, suffered from chronic traumatic encephalopathy (CTE) to a degree never before seen by BU researchers in such a young person, a University expert in the brain disease said on November 9.

Hernandez, just 27 when he hanged himself with a bedsheet, was riddled with Stage 3 CTE, to a degree that “we’ve never seen…in our 468 brains, except for individuals very much older,” Ann McKee, director of BU’s Chronic Traumatic Encephalopathy Center, told a news conference at the Metcalf Trustee Center. “Individuals with similar gross findings…were at least 46 years old at the time of death.”

CTE, which has four stages, is a progressive illness found in athletes and others who have suffered repeated concussions and other brain trauma. It is associated with dementia, mood changes, and aggression.

“Especially in the frontal lobes, which are very important for decision-making, judgment, and cognition, we could see damage to the inner chambers of the brain,” McKee said as she screened slides showing sections of Hernandez’s brain. “This would be the first case we’ve ever seen of that kind of damage in such a young individual.”

She said that in addition to deposits of the protein tau, which is associated with CTE, other evidence of the disease ranged across Hernandez’s brain. That included dilated ventricles—the chambers storing spinal fluid, which indicate the brain had shrunk—and an atrophied fornix (nerves associated with memory), “all of these caused by repetitive brain trauma.”

Noting that Hernandez did not suffer from other brain diseases, such as Alzheimer’s, McKee said that “in every place that we looked, it was classic CTE . This is substantial damage that undoubtedly took years to develop.”

Scientific figure showing images of CTE in Aaron Hernandez's brain compared to a normal 27 year old brain

Hernandez’s CTE-afflicted brain had an atrophied fornix (nerves associated with memory) compared to that of a normal person his age and enlarged ventricular cavities, involved in producing brain-cushioning fluid. Figure courtesy of McKee

McKee, a School of Medicine professor of neurology and pathology, had disclosed in September that Hernandez had suffered from CTE. Her center has done pioneering research on the illness through its bank of donated brains, including Hernandez’s.

She briefed reporters on details of her examination during BU’s second annual CTE Continuing Medical Education Conference.

Hernandez, once a promising tight end with the Patriots, was convicted in 2015 of murdering Odin Lloyd, a friend of his. While in jail, he was accused of a 2012 double murder in Boston. Earlier this year, he was acquitted of those killings, but hung himself in his prison cell shortly after.

“This brain has been one of the most significant contributions to our work,” McKee said, because of Hernandez’s youth and the organ’s pristine condition when it was turned over by the medical examiner. “The integrity of the brain tissue is so well preserved that we’re advancing our understanding of the disease at the submicroscopic level. We’re able to do things in this particular brain that we aren’t always able to do given the condition of a brain when we receive it.”

Helmets do not protect athletes from the jarring head movements associated with CTE, McKee told the conference. “It’s an intrinsic component of football,” she said. “Every time you have a tackle or a collision, you’re going to have these rapid forces affecting the brain.…That’s one of the difficulties of keeping football safe.”

Hernandez’s CTE prompted the player’s estate to sue the National Football League and the Patriots, arguing that they knew repeated head trauma could cause disease and had failed to protect Hernandez. As well, more than 100 former National Hockey League players have sued the NHL, seeking medical benefits on the grounds that the league should have known about diseases like CTE.

McKee said that “while I’m not going to connect the dots with his behavior or difficulties during life…the frontal lobes—and his were very severely affected—are involved in problem-solving, judgment, impulse control, and social behavior. The amygdala, which was affected in Aaron Hernandez as well, is involved in emotional regulation, emotional behavior, fear, and anxiety.”

She also said that while Hernandez had a genetic marker that makes people vulnerable to brain disease, it wasn’t certain that it contributed to his condition.