With the NFL season upon us, the public is reminded how dangerous the sport really is after another study on degenerative brain disease chronic traumatic encephalopathy (CTE) was released. A study published in the Journal of the American Medical Association on football players and CTE revealed the mounting evidence and impacts of head trauma.

Researchers found in a sample of 202 deceased players from a brain donation program that CTE was diagnosed in 177 players (87 percent), including 110 of 111 former National Football League players (99 percent). In a separate study, they examined the brains of military veterans and other athletes who had suffered head injuries and found that postmortem brains of 85 subjects had a history of repetitive mild traumatic brain injury. They were all males, ranging in age from 17 to 98 years, including 64 athletes, 21 military veterans and one individual who engaged in self-injurious head banging behavior.

The disease impacts behavior, mood and cognitive function. There are other disturbing symptoms like imbalance, confusion, memory loss, loss of consciousness, vision and hearing. "The fact that we were able to gather this many cases in that time frame says this disease is much more common than we previously realized," said senior researcher Dr. Ann McKee who works with the Boston University School of Medicine and the VA Boston Healthcare System.

News became grimmer when the National Institutes of Health decided to let their relationship expire with the NFL. "NIH officials decided months ago to let the agreement expire in August with more than half of the money unused, following a bitter dispute in 2015 in which the NFL backed out of a major study that had been awarded to a researcher who had been critical of the league."

But some players heard enough about CTE.

Baltimore Ravens offensive lineman John Urschel abruptly retired and tweeted that he will work on his Ph.D. in math at the Massachusetts Institute of Technology. Reportedly, a team source said Urschel's decision was linked to the results of the study, ESPN reported. “It wasn’t an easy decision, but I believe it was the right one for me,” he said, announcing he and his fiancee have expected their first child in December. “There’s not a big story here, and I’d appreciate the right to privacy.” Urschel is not the only player who is concerned about CTE. Buffalo Bills linebacker A.J. Tarpley and New York Jets left tackle D’Brickashaw Ferguson retired in 2016. Players like Calvin Johnson, Patrick Willis, Chris Borland, Jake Locker, Jason Worilds and Anthony Davis all exited early. So how did we get here sports fans? Let's look at the fast facts.

The NFL created the first committee.

The NFL created the Mid Traumatic Brain Injury (MTBI) committee in 1994, but the league never really took the situation seriously. The research program was under the supervision of a rheumatologist. "Concussions are part of the profession, an occupational risk," rheumatologist Elliot Pellman told Sports Illustrated.

Guidelines were created.

The American Academy of Neurology created guidelines for athletes returning after receiving a concussion in 1999. The guidelines recommended that athletes suffering from a loss of consciousness need to rest for a week. The NFL refutes the recommendations and said there was a lack of evidence to follow the AAN's recommendations. "They don't have guidelines,'' said Merril Hoge, who played eight seasons for the Pittsburgh Steelers and Chicago Bears. He also retired after suffering from chronic concussions in 1994. ''There is an enormous amount of pressure on the player, the owner and the doctor to get that player back out there.''

An autopsy triggers research.

Dr. Bennet Omalu discovered that concussions over time can cause permanent brain damage in 2002 after he performed an autopsy on former Steeler Mike Webster. “I had to make sure the slides were Mike Webster’s slides,” Omalu told FRONTLINE. “I looked again. I saw changes that shouldn’t be in a 50-year-old man’s brains, and also changes that shouldn’t be in a brain that looked normal.” The league was dismissive of his findings. Omalu was warned by an NFL physician who stated 'This country would begin to perceive football as a dangerous sport, that is the end of football.' Years later, McKee also confirmed CTE was real by finding that in 33 of 34 brains of former football players, CTE was a factor. She too, was dismissed by the league.

Junior Seau dies.

Linebacker Junior Seau killed himself in 2012 from a gunshot wound to the chest and upon further investigation, it was revealed that he had CTE. Portions of Seau's brain were sent to the National Institutes of Health for study. Seau's wife said she was told that "a lot of head-to-head collisions over the course of 20 years of playing in the NFL. And that it gradually, you know, developed the deterioration of his brain and his ability to think logically." Shortly after his death, 4,500 former players sued the NFL in federal court. The NFL reached a $765 million settlement over concussion-related brain injuries. They agreed to compensate victims and pay for medical exams and underwrite research, according to the league.

The NFL acknowledges CTE.

In 2016, it was the first time that the NFL admitted that there was a link between football and head injuries. NFL executive Jeff Miller told a congressional committee: "Well certainly Dr. McKee's research shows that a number of retired NFL players were diagnosed with CTE, so the answer to that question is certainly yes," Miller said. "But there's also a number of questions that come with that."

The research is convincing of the impact head trauma has on players. With the findings of 99 percent of athletes impacted with CTE according to Dr. McKee's report, who would want their kids playing football or any contact sport? The NFL is certainly a league at risk and they can no longer deny the hard evidence.