"Frustrated with being injured and wanting to prove my toughness to my teammates and coaches, I used my head more aggressively than I normally would have in practice, not understanding the damage I was doing to my brain," Turley told the House Judiciary Committee.
"I would like to tell you that this was an isolated incident -- just as Dr. Casson would."
Under questioning, Casson stuck to his position that there is no proven connection between football head injuries and brain disease.
"There is not enough valid, reliable or objective scientific evidence at present to determine whether or not repeat head impacts in professional football result in long-term brain damage," Casson said.
Rep. Linda Sanchez, D-Calif., and Rep. Steve Cohen, D-Tenn., were skeptical.
"I find it really ridiculous that he's saying that concussions don't cause long-term cognitive problems," Sanchez said. "I think most people you ask on the street would figure that repeated blows to the head aren't good for you."
Dr. Randall Benson, a neurologist and professor at Wayne State University, agreed with her.
"It's easy to wait for absolutes when there are no absolutes in what we do," he said. "It's common sense that playing football causes brain injuries. I think the questioning was somewhat of a waste of time because we all knew what Dr. Casson was going to say."
Sanchez noted that the league formed its concussion committee in 1994, and wondered aloud whether the NFL's recent moves on concussions took too long to implement.
"It seems to me that the NFL has literally been dragging its feet on this issue until the past few years," Sanchez said, later asking: "Why did it take 15 years?"
Casson said it was "completely incorrect," to characterize the committee as having ignored the problem.
He resigned as co-chairman of the NFL's committee on mild traumatic brain injury in November, saying it was a mutual decision between himself and commissioner Roger Goodell.
"There was a lot of lying," he added.
Casson said more research must be done on the effects of performance-enhancing drugs on the brains of football players. Some lawmakers questioned other witnesses about possible steroid links.
Goodell, who was not present, was grilled by lawmakers in October about his league's concussion policies.
Since then, the league has instituted stricter return-to-play guidelines for players showing concussion symptoms; required each team to enlist an independent neurologist as an adviser; entered into a partnership with Boston University brain researchers who have been critical of the league's stance on concussions; and conducted tests on helmets. The validity of those tests was questioned by witnesses at the hearing.
Asked for his thoughts on those changes, Casson questioned the merits of the independent neurologist mandate.
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"We don't know if these independent neurologists have expertise in head injuries," he said. "We don't know if their opinions are going to be independent and reliable and stand up to scrutiny."
Cohen said he sensed the league's recent moves could have resulted from concern about lawsuits, as in, "'What did we know and when did we know it?' -- and that should be secondary to the health of the NFL players and the college players and the kiddie league players and the high school players," he said.
Sanchez also pressed Casson on whether the "concept of permanent brain damage and dementia following repeated blows to the head is a very well-established and generally accepted principle in medicine."
Casson refused to give a direct answer, and Sanchez's tone grew more exasperated when she asked whether he would not "agree on something most laymen, probably most physicians, would agree with."
"We can disagree," he answered.
At one point, Casson said, "I'm not saying concussions are good for you."
"Well, that's the strongest statement I've gotten you to say," Sanchez said, drawing laugher in the packed conference room.
Another witness, NFL Players Association executive director DeMaurice Smith, told Congress the league hasn't shared the injury data it collected from every player from 2006-2008.
"We have written the NFL a letter asking to clarify whether they have given us all the data that they have available or only a portion of it," Smith said after his testimony. "As of today, I have not received an answer to that letter."
NFL executive vice president Joe Browne insisted the union has the same injury information that the league collected.
Copyright 2010 by The Associated Press