[Related: Invisible Killer: How Legal Fallout from Traumatic Brain Injuries May Forever Change the Way Sports Are Insured]

Yet the NFL has long denied the existence of reliable data concerning the cognitive decline of current and former players, and more and more league veterans are speaking out against the league, disclosing their ailments, stories, and difficulties stemming from head traumas throughout their careers.

Click through the following slides for nine stories from NFL veterans and active players who have spoken out against the dangers of the game.

Ray Easterling in 2004.

Ray Easterling

Former safety for the Atlanta Falcons, Ray Easterling, filed a lawsuit against the NFL in 2011 and would later be joined by more than 4,500 current and former players who claim that the league engaged in a “concerted effort of deception and denial” in its handling of concussions and brain trauma.

Easterling committed suicide at the age of 62 and was diagnosed with CTE following his death.

(Photo: Cherokee Tribune)

Junior Seau

Suicides in the NFL have followed a similar pattern to Easterling's. Loss of memory, as well as sharp and violent tempers, have led many former players to slip into depression, and sometimes even inflict self-harm.

Junior Seau, a former linebacker for the San Diego Chargers, Miami Dolphins and New England Patriots, resorted to suicide to escape the traumas associated with CTE. The 12-time Pro Bowler shot himself in the chest in May 2012. CTE was confirmed in Seau's autopsy.

(AP Photo/Charles Krupa)

One of many concussions: Wayne Chrebet lays unconscious after he took a hit on a reception.

Wayne Chrebet

New York Jets receiver Wayne Chrebet was knocked out cold during a game against the New York Giants in November 2003. After being examined by the Jets' team doctor, who was also head of the NFL's Mild Traumatic Brain Injury (MTBI) Committee, he was sent back into the game.

It was a pattern of denial, he says now. Chrebet was forced to retire from football at 32 after suffering too many concussions.

In 2004, the MTBI committee published a paper in Neurosurgery, emphasizing that the NFL's concussion problem is relatively small. According to the paper, “a total of 92% of concussed players return to practice in less than seven days,” and more than half of players returned to play within a day of the incident, as symptoms generally dissipated in a “short time in the vast majority of cases.”

Chrebet, and many others, would likely argue otherwise.

(AP Photo/Tim Larsen)

Mike Webster

Mike Webster, who played in the NFL for years with the Pittsburgh Steelers and Kansas City Chiefs, filed a disability application with the NFL Retirement Board in 1999 after struggling with cognitive problems. Webster claimed that his NFL career has lead to dementia. The Board ruled that Webster's head injuries, which have left him “totally and permanently disabled,” are simply the “result of head injuries he suffered as a football player.”

Webster's attorney claimed that the ruling shows the league should have known there was a link between football and brain damage.

“If the NFL takes the position that they didn't know or weren't armed with evidence that concussions can cause total disability—permanent disability, permanent brain injury—in 1999, that evidence trumps anything they say.”

Webster died in 2002 at age 50.

Allegheny County medical examiner Dr. Bennet Omalu took a closer look at Webster's brain during his autopsy, discovering the first evidence of a brain disease that had never been previously identified in football players, Chronic Traumatic Encephalopathy, or CTE. Sports medicine researcher at the University of North Carolina Dr. Kevin Guskiewicz subsequently published a paper that suggested that repeat concussions may lead to slower recovery of neurological functioning.

The paper reads, “our study suggests that players with a history of previous concussions are more likely to have future concussive injuries than those with no history; one in 15 players with a concussion may have additional concussions in the same playing season; and pervious concussions may be associated with slower recovery of neurological function,” sparking the rise in research on concussions in the NFL.

(AP Photo/Gene J. Puskar)

Terry Long

Former Steeler Terry Long committed suicide by drinking antifreeze in June 2005. Dr. Omalu later reported that he had found CTE in Long's brain as well.

Dr. Joseph Maroom, Steelers team doctor and a future member of the MTBI committee, told the Pittsburgh Post-Gazette that Omalu's conclusion that Long's suicide may have been the result of depression caused by head traumas throughout his NFL career was “fallacious reasoning.”

“To go back and say that he was depressed from playing in the NFL and that led to his death 14 years later, I think is purely speculative,” Maroon says in the paper. “He could have had a head injury that wasn't reported before football….And that's why I'm saying it's so speculative.”

Other MTBI committee members Dr. Ira Casson and Dr. David Viano, along with Dr. Elliot Pellman, requested that Neurosurgery retrace Omalu's CTE paper, stating, “Omalu et al's description of chronic traumatic encephalopathy is completely wrong. The diagnosis of a chronic condition requires a medical history indicating a long-standing nature of illness [and] such a history is completely lacking in Omalu's report.”

Dr. Omalu followed up with a second paper after discovering CTE in Long, and as with Mike Webster, he links depression with the players' long NFL careers.

(AP Photo/File)

Ricky Watters

Super Bowl Champion Ricky Watters addressed fans as an honorary captain before the Philadelphia Eagles played the Detroit Lions in 2012, revealing that he would forever suffer pain from head to toe as a result of his playing days.

Over his career in the NFL, Watters suffered his fair share of injuries. He tore his right medial collateral ligament and left posterior cruciate ligament, causing him severe knee pain. He also has five pins in his right ankle and one in his right foot, and a metal plate envelops his femur. His index finger was shattered and never properly healed, robbing him of his favorite hobbies: drawing and painting.

Watters' physical ailments don't stop there. He also suffers from an undiagnosed crack in his sternum, back issues, arthritis and failing kidneys at only 43 years of age. Like many of former NFL players, Watters, too, suffers headaches, fatigue, forgetfulness, and other symptoms associated with head trauma.

Watters has admitted to playing without his full mental faculties “hundreds of times,” and is one of the plaintiffs in the lawsuit against the NFL.

(AP Photo/Scott Iskowitz)

John Mackey

This Hall of Famer and tight end for the Baltimore Colts and San Diego Chargers served as the first head of the NFL Players Association.

Mackey also suffered from frontotemporal dementia after he left the game, which made him confused, paranoid and angry. At the age of 65, he entered an assisted-living facility, and Mackey passed away at the age of 69.

The autopsy report showed clear evidence of CTE.

(AP Photo/ Steve Ruark)

Ted Johnson

The New England Patriots' Ted Johnson told the New York Times, in the wake of his retirement in 2005, that he suffers from memory loss, an addiction to amphetamines and agoraphobia after suffering two concussions in the same week in August 2002.

Johnson claims that Coach Bill Belichick sent him back on the field for regular contact play four days later, against advice from the Patriots' team trainer. Belichick told The Boston Globe that Johnson should have said something. “If Ted felt so strongly that he didn't feel he was ready to practice with us, he should have told me,” Belichick said.

(AP Photo/Steven Senne)

Joe DeLamielleure with his wife Gerri at their home.

Joe DeLamielleure

Though CTE cannot be definitively diagnosed until an autopsy has been performed, Joe DeLamielleure knows he is showing early symptoms: depression, short-term memory loss and anger issues.

After 13 years in the NFL, DeLamielleure knows he has CTE and estimates he has suffered hundreds—possibly more than a thousand—concussions throughout his football career. He was also one of the first former NFL players to donate his brain to Boston University following his death; some 500 NFL veterans have since followed suit. So far, CTE has been found in 18 of the 19 former players whose brains have been studied.

A major critic of the NFL and NFLPA for their treatment of retired players, DeLamielleure is an advocate for solutions to mental health problems plaguing his fellow veterans.

The question for many NFL players becomes: Is it worth it?

DeLamielleure answers, “No.”

Sporting News subsequently asked former players whether if, knowing what they do now about the risks associated with their NFL careers, they would do it all over again. DeLamiellure was one of nine players who said “no.” A tenth player remarked, “I don't think so,” and another said, “I don't know.”

But these men seem to be in the minority. Of the 125 players surveyed, 96 players answered affirmatively.

Some responded with utter enthusiasm.

“Absofrickinlutely!” offensive lineman Jim Sweeney wrote. And Hall of Famer Jack Youngblood, who is experiencing memory and cognitive issues remarked that he would do it over again, “in a minute.” “Being the President of the United States isn't anywhere near that. There is nothing like playing on Sunday,” Youngblood said.

Many who said that they would do it over again remarked that they would choose that path because of the thrill of playing in front of adoring fans, and others claim that they could not imagine their lives without the lasting friendships that stemmed from their NFL career.

However, 15 players who said “yes,” admitted that they would have retired sooner, tried not to hit their heads so much, would try not to be so tough and would listen to their doctors.

(AP Photo/Bob Leverone)