'They're in the violence business': The Aaron Hernandez documentary highlights how the brain disease CTE has affected the entire NFL

The documentary chronicles the story of Hernandez, a former New England Patriots player who died by suicide while serving a life sentence for killing Odin Lloyd, the boyfriend of his fiance's sister.
After his death, researchers found that he had severe chronic traumatic encephalopathy (CTE) , a brain disease caused by repetitive brain trauma.
"Killer Inside" features long segments on the brain disease, including interviews from other football players. It does not tie Hernandez's crimes specifically to the disease.
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A new Netflix documentary about former New England Patriots tight end Aaron Hernandez highlights how brain trauma is affecting the NFL's players.

While "Killer Inside: The Mind of Aaron Hernandez" does not blame chronic traumatic encephalopathy (CTE) for Hernandez's criminal behavior or the murder of Odin Lloyd, which Hernandez was sentenced to life in prison for the documentary does give insight into how the untreatable disease affects NFL players for the rest of their lives.

Through interviews with lawyers, Hernandez's friends, and former NFL players, the documentary tells stories of CTE, which can only be diagnosed after death.

Chris Borland , a former 49ers linebacker who retired after just one year in the league over fears of the longterm effects of head injuries, said in an interview that he was experiencing symptoms of concussions including ringing in the ears and imbalance every day.

"In my minimal interactions with folks high in the NFL, I think there's a certain degree of hubris. You know, they own a day of the week," he told "Killer Inside" filmmakers. "Football's a religion."

"No matter whether or not they're throwing a flag, or claiming concussions are down, or taking players into the blue tent, the reason football is the most popular sport is because it's violent," he added, referencing penalty flags for helmet hits, and the blue medical evaluation tents on the sidelines of NFL games. "They're not in the health business. They're in the violence business."

The documentary covers the CTE diagnoses of Mike Webster and Junior Seau

In this 1988 season file photo is Pittsburgh Steelers center Mike Webster AP Photo/Gene J. Puskar, File

Before delving into Hernandez's own CTE diagnosis, the documentary highlights the diagnoses of Mike Webster , who was the first former NFL player to be diagnosed with the disease after he died of a heart attack in 2002, and Junior Seau , who was diagnosed after he died by shooting himself in the chest in 2012.

Retired Patriots cornerback Leigh Bodden told filmmakers he wasn't shocked at Hernandez's CTE diagnosis because he had already known what happened to Seau, another Patriots teammate.

"Having CTE be the kind of thing they both shared is eye-opening to athletes and to everybody in the football world," he said.

As more people learn about the problems CTE can cause, more players are retiring from the NFL early.

Researchers have shown that head hits in youth sports increase the risk of developing CTE. Another study has shown that players are at a higher risk if they play longer.

Carolina Panthers linebacker Luke Kuechly announced his retirement on Wednesday at just 28 , saying it was the "right thing to do."

New England Patriots Junior Seau speaks to reporters before training at the Oval Cricket Ground ahead of their NFL game against Tampa Bay Buccaneers in London October October 23, 2009 Reuters/Luke Macgregor

The NFL says it supports scientific research into CTE, pledging $100 million into independent studies in 2016. After Boston University's CTE Center released a study in 2017, which found evidence of the disease in 110 out of 111 former players, the NFL issued a statement saying the research added value "in the ongoing quest for a better understanding of CTE" but said there are "unanswered questions relating to the cause, incidence, and prevalence of long-term effects of head trauma such as CTE."

Hernandez had advanced CTE when he died by suicide in 2017

When Hernandez's brain was examined after his death in 2017, Ann McKee, a neuropathologist and expert in neurodegenerative disease at Boston University's CTE center, said his diagnosis was advanced.

"He had a very advanced disease. And not only was it advanced microscopically, especially in the frontal lobes, which are very important for decision making, judgment, and cognition," she said in "Killer Inside."

Patrick Haggan, the prosecutor on Hernandez's second trial told interviewers in "Killer Inside" that he researched CTE after hearing about Hernandez's diagnosis.

"I started to look at the signs of CTE impulsiveness, rash decisions, sometimes propensity to be violent. It was Aaron Hernandez," he said in the documentary. "And if you look at everything that this young man had going on not only physically, but mentally, emotionally, from what had happened when he was a child, and what had happened in his own life, then on top of it you add the CTE it all made sense that this tragedy had probably begun, or the seeds of this tragedy had started many, many years earlier."

Former NFL player Aaron Hernandez and defense attorney Charles Rankin wait in the courtroom during the jury deliberation in his murder trial at the Bristol County Superior Court in Fall River, Massachusetts, April 10, 2015..JPG REUTERS/CJ Gunther/Pool

JermaineWiggins, a former New England Patriots tight end, believes there was something worse going on with Hernandez, and that CTE wasn't to blame for his crimes.

"I think it's a cop-out [to blame CTE]," he said in "Killer Inside." "There are thousands of former football players out there that might have dealt with concussions. I've dealt with them. So to use that as a cop-out? No, we're smarter than that, people."

In the "Killer Inside" segment on CTE, filmmakers included an old local TV interview of Patriots owner Robert Kraft where he encourages people to still play football.

"My sons and grandson played, I played, and I'd recommend to every other mother out there who wants their son to grow up special that they should play too," he said.

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