Washington (CNN) -- Are professional football players at greater risk of dementia and other neurological problems?
The question took center stage in Congress on Wednesday during hours of testimony from doctors, retired athletes and National Football League executives. A congressional committee waded through conflicting perspectives on past and current studies, and urged the use of greater precautions to help protect participants in one of America's most popular pastimes.
The hearing occurred against the backdrop of negotiations over a new agreement to replace the NFL collective bargaining agreement, which expires next year. Critics have argued that the league does not do enough to provide care for former players suffering from debilitating brain injuries.
"Surely, an $8 billion a year industry can find it within its budget to make sure players are adequately protected and that any victims of long-term brain disease are fairly compensated," said Michigan Rep. John Conyers, the Democratic chairman of the House Judiciary Committee.
These are "life and death issues. They go to the heart of our nation's most popular sport, and equally importantly, they affect millions of players of all ages and their families."
Conyers' committee heard from NFL Commissioner Roger Goodell, former Pittsburgh Steelers running back Merril Hoge and DeMaurice Smith, the head of the players union, among others.
Republican leaders said that although the issue should be taken seriously, Congress should not use it to attempt to influence the upcoming bargaining process.
We should make "every effort to make pro football as safe as reasonably possible," Texas GOP Rep. Lamar Smith said. But "we cannot legislate the elimination of injury from the games without eliminating the games themselves. ... The NFL does not need Congress to referee this issue."
Goodell cited multiple policy changes implemented during his tenure, including a retroactive increase in pension benefits and the 2007 creation of the NFL's 88 Plan, which helps cover treatment costs for retirees suffering from dementia.
"We will not reduce or eliminate funding for these agreements" based on the status of collective bargaining negotiations, he promised. "Medical considerations must always come first. ... We are changing the culture of our game for the better."
Committee members cited a range of studies highlighting the long-term impact of concussions suffered by NFL players. A 2003 University of North Carolina study, according to Conyers, found that players who suffered multiple concussions were three times more likely to suffer clinical depression than the population as a whole.
A 2005 follow-up study showed that NFL players suffering concussions had five times the rate of cognitive impairment, Conyers noted, and retired players were almost 40 percent more likely to suffer from Alzheimer's disease than the population as a whole.
A University of Michigan study released this year showed that more than 6 percent of former NFL players over the age of 50 reported receiving a diagnosis of dementia, five times higher than the national average.
There is "a serious public health problem today resulting from repetitive head trauma too often experienced by NFL players," said Dr. Robert Cantu, who works at the Boston University School of Medicine.
The NFL has questioned the methodology of such studies, however, and is conducting its own examination of the issue. Critics consider the NFL's research to be compromised by a conflict of interest.
Dr. Ira Casson, who is overseeing the current NFL study, declined to testify at the hearing.
Dr. David Weir, a University of Michigan researcher, noted that a previous NFL-sponsored study he conducted showed 96 percent of league retirees reported no cognitive impairment or dementia.
"Those numbers may or may not indicate an elevated risk from a career playing football," he argued. "We can't draw a conclusion, and no responsible scientist would do so."
Dr. Andrew Tucker, the head team physician for the Baltimore Ravens, said that both doctors and athletes take concussions far more seriously today than they did 10 or 15 years ago.
"I don't think it is wise to indict the care being given today's players based on reports [from players treated] a generation ago," he said.
But Gay Culverhouse, former president of the Tampa Bay Buccaneers, argued that very little has changed.
"The players get to a point where they refuse to tell the team doctor that they have suffered a concussion," she said. "They do not self-report because they know there's a backup player sitting on the bench ready to take their position. ... They need those extra yards and those interceptions in order to make their salaries."
Culverhouse said team doctors have a strong interest in their team's success on the field and could therefore not be relied upon to provide an honest assessment of a player's condition after receiving a possible concussion.
"If a player chooses independent medical counsel, he is considered to be not a team player," she said. "He becomes a pariah to the team. We've got to stop that."
Culverhouse argued in favor of having an independent neurologist at every NFL game to diagnose players from both teams.
Former New York Giants defensive lineman George Martin, now head of the NFL's alumni association, said most players have four primary safety-related concerns.
First, he said, there should be a greater emphasis on injury prevention through rule changes and better protective equipment. Second, there should be easier access to quick diagnoses and treatment without "laborious and agonizing red tape."
Third, medical treatment for retired players should not lead to financial ruin. Finally, he added, more comprehensive studies are required to accurately assess the extent of the problem.
Hoge recalled losing the ability to read, suffering from depression and being unable to recognize his family after receiving multiple concussions in 1994.
He said he was cleared to play only five days after one of his concussions following a discussion with a family practitioner over the phone.
"What happened to me would not happen in the National Football League today," he said. "There have been significant changes in the [NFL]. ... That does not mean we are all the way there. [But] we are on our way."