By Matt Dolloff, CBS Boston

BOSTON (CBS) — American football has always been an inescapably violent, barbarous sport. It carries significant risks of brain trauma that lead to concussions or the degenerative brain disease chronic traumatic encephalopathy, or C.T.E. This is mostly common knowledge now, but little was known decades ago when many of the deceased former players discovered to have had C.T.E. played. While it has mostly been discovered in players who played positions that required constant physical contact and repeated blows to the head, like linemen or running backs, it has been found in quarterbacks, too.

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Former Oakland Raiders great Ken Stabler, who lost his battle with colon cancer last July at age 69, is the latest signal-caller to have C.T.E. discovered in his brain after he agreed to donate it for research at the Boston University School of Medicine, the New York Times reported Wednesday. He is not the first quarterback to posthumously receive the diagnosis (it is not possible to test for C.T.E. in living patients), but Stabler, a former NFL MVP and Super Bowl champion in 1976, is the most high-profile to date at the quarterback position and arguably the most well-known former player with C.T.E. yet.

Stabler’s diagnosis should not come as a surprise, but it should serve as a warning to those who choose to play football: everyone on the field is putting their long-term mental health at risk, even the quarterback.

A research team at the BU School of Medicine led by Dr. Ann McKee found that Stabler suffered from “severe Stage 3 C.T.E., believed to be caused by repeated blows to the head,” according to the New York Times report, which features a photo of Stabler’s brain showing where researchers found shrinkage, torn tissue, and other signs of C.T.E.

Stabler suffered severe mental anguish in the final years of his life, according to family members who witnessed him struggle to get a full night’s sleep, live in complete silence to avoid any kind of loud noise, and repeat stories that he had just told minutes earlier. Symptoms of Alzheimer’s disease and dementia, like memory loss and general confusion, are common in C.T.E.

Stabler did play an unusually long career for most NFL players, starting 146 games in 15 seasons with the Raiders, Houston Oilers, and New Orleans Saints, which undoubtedly contributed to his comparatively high level of brain trauma. But the fact that he played quarterback, the position that frequently takes the fewest hits on the field, yet had as much or more damage done to his brain as many former players who played more physical positions, can only increase the concerns surrounding football and the ostensibly unavoidable head trauma that comes with it.

Dr. McKee, who is also professor of neurology and pathology at BU, described Stabler’s brain condition as a “pretty classic” case of C.T.E., adding “It may be surprising since [Stabler] was a quarterback, but certainly the lesions were widespread, and they were quite severe, affecting many regions of the brain.” Stabler’s C.T.E. diagnosis brings nothing new to the table as far as the dangers of concussions in football, or the negligence and lack of knowledge that battered players from Stabler’s era and continues to plague them today.

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Only now is the game of football beginning to steer away from the extreme physicality that for decades has defined it.

Stabler expressed concerns in the final years of his life about his grandsons playing football, fully aware of the long-term damage it could inflict on their brains if they repeatedly smashed helmets from an early age. Stabler started playing football at age 9 and played in the NFL until age 39.

The kind of sweeping, radical changes that may be necessary for football to live on for decades beyond 2015 may be far off from even being considered in the NFL or NCAA, or even high school. But changes are already happening at the youth level – at least, in Massachusetts they are. Somerville’s recreation department announced last month that they would no longer “fully fund a program” relating to full-contact football, switching exclusively to a non-contact flag football program to begin in the summer of 2016. They are just the latest city to commit to the rise of youth participation in non-contact football – and the decline in full-contact participation.

Stabler’s partner Kim Bush reiterated the unfortunate truth that football itself is the cause of brain trauma. The best helmets in the world can’t fully stop the human brain from bumping around inside the skull, and the relentlessly repetitive game’s physicality is what needs to disappear if players want to play without risks.

Will the NFL eventually morph into flag football, two-hand touch, or some other non-contact sport? The idea sounds preposterous today, but many of today’s youths (and, more importantly, their parents) may be on board with it, based on the shifts happening in certain communities.

C.T.E. discoveries in former players will only continue to rise and magnify the need for change. Since no player on the field, not even the quarterback, is completely safe, America’s most beloved game may need a major transformation in order to survive.

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Matt Dolloff is a writer for CBSBostonSports.com. His opinions do not necessarily reflect that of CBS or 98.5 The Sports Hub. Follow him on Twitter @mattdolloff and email him at mdolloff@985thesportshub.com.