02/05/2016 05:34 EST | Updated 02/05/2017 05:12 EST

Are O.J. Simpson And Johnny Manziel Examples Of The Effects Of CTE?

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MRI scan of the human brain

What do O.J. Simpson and Johnny Manziel have in common? They both won the prestigious Heisman Trophy award, in 1968 and 2012 respectively. They were both phenomenal football players. And both sports stars were plagued with bouts of rage and aggression off the field. Often directed towards their significant others. Could they both be victims of CTE?

Chronic traumatic encephalopathy, known as CTE, is caused by repeated traumatic injury to the head. Symptoms include memory loss, aggression, confusion, and depression. Dr. Bennet Omalu, subject of the recent film Concussion, was the first to recognize the link between NFL players and the neurological condition, previously believed to only affect boxers.

CTE was found in the brain of Jovan Belcher, who murdered his girlfriend before committing suicide; Shane Dronett, who pulled a gun on his wife before turning it on himself; Chris Henry, who fell from a truck during a domestic dispute with his girlfriend; and Junior Seau, who was arrested for domestic violence and later killed himself. Dave Duerson, Ray Easterling, Terry Long, Adrian Robinson and Andre Water all committed suicide. Tom McHale and Tyler Sash died from an accidental drug overdose. Justin Strzelczyk spoke to friends of "evil" voices before driving into oncoming traffic the following day. He died instantly when he collided with a tractor-trailer.

NFL star Paul Oliver had never experienced any signs of aggression until several head injuries turned him "into a monster," according to his widow.

"He's never been like that. And every time after, he would always say, 'I don't know what's wrong with me. Something's wrong with me.' He's like, 'I can't control myself anymore.'

After Paul Oliver committed suicide, CTE was found in his brain.

This is just from the NFL roster. Professional wrestler Chris Benoit murdered his wife and son before killing himself. He, too, had CTE. Most recently, BMX legend Dave Mirra committed suicide. Once again, CTE could be to blame.

Manziel's off-field issues have mostly been blamed on drug and alcohol abuse -- although those with CTE often use drugs and alcohol to self-medicate.

Chris Nowinski, head of Concussion Legacy Foundation, said:

"Many [athletes with CTE] have developed drug and alcohol abuse issues, a lot of [athletes with CTE] were actually self-medicating through headaches, didn't have any impulse control [and] would get addicted to things."

There's also a link between instances of domestic violence and CTE.

Boston University found a significant link between instances of domestic violence and CTE. In a study, researchers found lesions in the anterior temporal lobe, which is responsible for regulating self-control and emotions. Dr. Ann McKee said:

"But we know that with CTE it leads to a short fuse. These guys used to be fine. They were entirely reasonable at all times of day. But now these guys are assaultive, they're overreacting. They're paranoid, they're jealous."

NFL player Deion Sanders recently decided to place the blame of Manziel's struggles on his abused girlfriend -- Colleen Crowley.

Crowley has often been the target of Manziel's wrath, and domestic violence has been the epicenter of his legal woes. In October 2015, Crowley tried to jump out of Manziel's moving car after he attacked her while driving. Crowley refused to press charges. Most recently, after sustaining a concussion in January 2016, Manziel attacked Crowley again in Dallas, Texas. Allegedly, Manziel struck Crowley several times, and then dragged her by the hair in an attempt to force her into a vehicle. He threatened to kill her and himself. Manziel has denied the charges, but the NFL decided to release him from his contract with the Cleveland Browns.

The infamous O.J. Simpson had been charged with domestic violence prior to the slaying of his ex-wife, Nicole Brown Simpson. Despite being acquitted of the charges, O.J. apparently described the murders in a book, ghostwritten by Pablo Fenjves but linked to Simpson, published after his acquittal, entitled "If I Did It: Confessions of the Killer."

"I looked down and saw her on the ground in front of me, curled up in a fetal position at the base of the stairs, not moving. Goldman was only a few feet away, slumped against the bars of the fence. He wasn't moving either. Both he and Nicole were lying in giant pools of blood. I had never seen so much blood in my life. It didn't seem real, and none of it computed. What the fuck happened here? Who had done this? And why? And where the fuck was I when this shit went down? It was like part of my life was missing--like there was some weird gap in my existence. But how could that be? I was standing right there."

This appears to be a textbook example of someone suffering with CTE. In fact, Dr. Bennet Omalu recently stated that he would "bet my medical license" on O.J. having CTE, but until a post-mortem examination, it's impossible to know for certain.

As for Johnny Manziel, a once illustrious football career has now become tainted with allegations of alcoholism and abuse. His father, Paul Manziel, recently told the press that he feared his son wouldn't see his next birthday unless he sought treatment for addiction. But if CTE is to blame, then alcohol addiction might be the symptom, but not the cause.

With so many victims lining up from both the field and the sidelines, hopefully the NFL -- and all high impact professional sports associations -- will invest more research into the prevention of CTE.