A former NFL star who killed himself while serving a life sentence for murder had a brain disease linked to repeated head trauma, researchers have found.
Aaron Hernandez, 27, had the most severe case of chronic traumatic encephalopathy (CTE) neurologists at Boston University had even seen for someone of his age, according to his lawyer Jose Beaz.
The condition, which has been diagnosed in a large number of former and deceased NFL players, can lead to aggression, dementia and suicidal thoughts or behaviour.
Former New England Patriots star Hernandez had been serving a life sentence without parole for murder when he was found hanged in his cell in April.
Days earlier he was cleared of killing two other men in a drive-by shooting.
Dr Ann McKee, director of Boston University’s CTE Centre, said Hernandez’s brain showed signs of stage 3 of the disease, with stage 4 being the most severe form.
The 27-year-old also had early brain atrophy and large perforations in a central membrane, she added.
The findings have prompted Hernandez’s daughter to launch a $20m lawsuit against the NFL and New England Patriots.
An NFL spokesperson said: “We have not seen a copy of the suit and cannot comment at this time.”
In July, research by Boston University CTE Centre showed that of 111 deceased NFL players studied, 110 had CTE.
Hernandez is not the first NFL player who suffered with the condition to take his own life.
In November 2006, Andre Waters died of a gunshot wound to the head and tests later found his brain tissue had degenerated into that of an 85-year-old man with similar characteristics as those of early-stage Alzheimer’s victims.
Retired four-time Pro Bowl star Dave Duerson fatally shot himself in the chest in February 2011, leaving a message asking his family to “see that my brain is given to the NFL’s brain bank”.
Linebacker Junior Seau died in identical circumstances in May 2012, leading to a $765m lawsuit against the NFL from his family.
Seven months later, Kansas City Chiefs star Jovan Belcher shot dead his girlfriend before driving to training and turning the gun on himself in front of team officials.