ROSEMONT, Ill. (AP) _ Troy Vincent recalls going back to the huddle and forgetting to look at the sideline for the play, even though it was his job to relay the signal.
He mentions the days after one concussion when he couldn't remember phone numbers and kept thinking his car was running. When he sees clips of himself knocked unconscious, he cringes.
``I'm not sure if we _ athletes _ know what a concussion is,'' said Vincent, a veteran defensive back and the president of the NFL Players Association.
The NFL is taking steps to educate players on the subject and make sure they report concussions, implementing a whistle-blower system when training camps start next month. The league hopes that will ease pressure on players to take the field with a concussion.
``It's an important element of what we're trying to accomplish here,'' NFL commissioner Roger Goodell said Tuesday after a conference with medical personnel from every team in the league. ``I have said repeatedly and will continue to say that medical decisions must override any competitive decisions.
``And if anyone feels they are being forced onto the field when they are not ready to play, we want to know about that and look into it.''
Although details need to be worked out with the players union, the new system allows anyone to anonymously report when doctors are pressured to clear players or when players are pressured to play. It's one of several changes the league is making in its effort to manage concussions.
The deaths of four players in recent years have raised awareness of the issue, and the meeting was held to discuss the latest information on treating the condition.
Besides implementing the whistle-blower system, the league will require all players to undergo baseline neuropsychological testing starting this season. Rules requiring players to properly buckle their chin strap will be enforced. And a brochure will be distributed to players to help educate them and their families about concussions.
The league has been examining the issue for 14 years, and medical meetings are not unusual. What set Tuesday's conference apart was its scope and list of speakers, some of whom have been critical of the NFL.
The heightened awareness comes amid studies indicating that players who suffered multiple concussions might be susceptible to neurological disorders later in life. And it comes amid reports suggesting brain damage may have been a factor in the deaths of former Philadelphia Eagles safety Andre Waters and former Pittsburgh Steelers offensive linemen Mike Webster, Terry Long and Justin Strzelczyk in recent years.
Waters committed suicide in November. Long killed himself in 2005. Webster suffered brain damage and was homeless before he died of heart failure in 2002. Strzelczyk crashed his pickup truck while being chased by police in 2004.
``I don't think we can conclude what exactly caused this,'' said Dr. Julian Bailes, a neurosurgeon at West Virginia University and a former Steelers physician who has seen Strzelczyk's pathology report. ``Although if you go through the list of potential causes, certainly trauma to me is No. 1. Is that football trauma? Is that NFL trauma? Is that high school trauma? Is that falling off a bike as a kid? I don't know.''
Bailes also is the medical director at the University of North Carolina's Center for the Study of Retired Athletes, which found in a recent study of more than 2,500 retired NFL players that those who had at least three concussions during their careers had triple the risk of clinical depression as those who had none. And those who recalled having one or two concussions were 1 1/2 times more likely to be diagnosed with depression.
The study involved only those concussions suffered in the NFL, even though players may also have had some during high school and college. Many were active before the league began its concussion management program in the mid-1990s and before studies sponsored by the NFL and NCAA prompted new helmet designs.
The NFL questioned the findings but is conducting its own study on retired players.
Concussions can be difficult to diagnose, and players who were conditioned when they were children to play hurt are reluctant to reveal injuries.
``Who wants to come out of the game?'' wondered Vincent, who has been diagnosed with six or seven concussions in 15 seasons. ``No player wants to sit on the sidelines.''
And if a coach asks if a player is OK?
``When you're asking a player on the sideline if he wants to go back in the game, the answer is going to be yes,'' said Mark Bruener, a member of the NFLPA's board who has been diagnosed with four concussions in 12 seasons.
Former New England linebacker Ted Johnson told The New York Times in February he wasn't given a choice. And now, he's showing signs of early Alzheimer's disease.
Johnson told The Times his mental problems began in 2002 when he had two concussions in four days _ during an exhibition game and then after coach Bill Belichick pushed him to join full-contact practice against the advice of the team's top trainer.
The whistle-blower system might prevent problems. More education should help, too.
``I think players will do a better job policing,'' Vincent said. ``You're in the huddle, you see your colleague's dinged, just tell the official. Now, because of the attention that it's getting, I think the officials will be more aware, and the players in the huddle will be more aware.''