Lawyers for Aaron Hernandez have refiled a lawsuit against the NFL and its former helmet manufacturer, claiming that the 27-year-old former football player “had a horrendous existence” as a result of a result of severe chronic traumatic encephalopathy (CTE), a degenerative brain disease that has been linked to head trauma.
In the complaint obtained by PEOPLE, Hernandez’s estate maintains that the former New England Patriot sustained multiple blows to the head while wearing Riddell helmets. As a result, the estate says, he suffered from Stage 3 CTE — a rarity in football players his age.
“Aaron experienced a chaotic and horrendous existence in many respects, due to his undiagnosed brain injury,” the estate alleges in its complaint. In another part of the lawsuit, the estate says that CTE causes “aggression, explosive behavior, loss of concentration, mood swings, depression, apathy, and cognitive impairment.”
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According to a statement from Boston University’s CTE Center, the 27-year-old former football player “had early brain atrophy and large perforations in the septum pellucidum, a central membrane.”
This means his brain had started to shrink and there were holes in the membrane that divides the two cerebral hemispheres.
“Aaron Hernandez’s advanced stage 3 of CTE is normally found in the median age of a 67-year-old man,” Hernandez family attorney Jose Baez told PEOPLE last month.
Hernandez’s family believes his CTE contributed to some of his behavior. He hanged himself with a bed sheet just five days after he was acquitted of double murder charges in the deaths of two men outside a Boston nightclub in 2012. He was serving a life sentence for the 2013 murder of Odin Lloyd, his fiancée’s sister’s boyfriend. He was not eligible for parole.
(With Hernandez’s death, his conviction for Lloyd’s murder was voided because of a little-known legal doctrine in Massachusetts that vacates convictions if a defendant dies before their direct appeal is complete.)
“While we still maintain that he was innocent [of the murders], the CTE can explain a lot of his behavior,” Baez says. “The impulsiveness can be a symptom of CTE. We think that the CTE explains a lot of things that Aaron did, including his supposed suicide.”
CTE cannot be diagnosed in living subjects; it is only found during autopsies. Several former NFL players, including Junior Seau, were diagnosed with the disease after committing suicide.
In July, Boston University researchers published a study in the Journal of the American Medical Association that claimed that CTE was detected in 99 percent of brains obtained from National Football League players. Some have cautioned that the findings might have a selection bias because the brains were submitted by family members of players who showed possible symptoms of the disease.
Attorneys for the NFL declined comment on the case. Representatives for Riddell Helmets did not return PEOPLE’s call for comment.