Six former players and one current player have sued the NFL in Philadelphia over the league's handling of concussion-related injuries, the first potential class-action lawsuit of its kind.

The players accuse the league of training players to hit with their heads, failing to properly treat them for concussions and trying to conceal for decades any links between football and brain injuries.

The plaintiffs include two-time Super Bowl champion Jim McMahon, who has said he played through five concussions but now frequently walks around "in a daze" and forgets why he entered a room.

The suit accuses the NFL of negligence and intentional misconduct in its response to the headaches, dizziness and dementia that former players have reported. The suit, filed Wednesday, seeks medical monitoring along with funds to pay for the care of injured players.

NFL spokesman Brian McCarthy said the league had not yet seen the lawsuit but would vigorously contest any such claims.

Players' lawyer Larry Coben of Philadelphia said one client may soon lose his home because of his health-related financial problems.

"The big issue, for us, is they were told for decades to lead with their heads," Coben told The Associated Press. "The NFL would never admit that there's any correlation (to later health problems)."

Seventy-five retired players sued the NFL last month in Los Angeles, alleging the league knew since the 1920s of the harmful effects of concussions, but concealed them from players, coaches, trainers and the public until June 2010. That suit also names helmet-maker Riddell, the NFL's official helmet supplier, as a defendant.

The federal suit filed in Philadelphia, though, is the first to seek class-action status and potentially include anyone who had played in the league and suffered a concussion or head injury.

"Our goal is much larger, perhaps more daunting," said Coben, who has previously sued over brain injuries incurred in high school football.

"We have to ultimately determine how many people are in the (legal) classes. How many people from the `70s are experiencing this, how many people from the `80s, from the `90s? And then, what are the losses?"

The other plaintiffs include Cleveland Browns offensive tackle Joe Thomas, 26; Ray Easterling, 61, a defensive back for the Atlanta Falcons in the 1970s; and Wayne Radloff, 50, an offensive lineman for the Falcons and San Francisco 49ers in the late 1980s.

Some plaintiffs receive benefits from the league's 88 Plan, which provides funding from the NFL and the players union to help care for players afflicted with dementia or related brain problems. However, Coben said the payments fall far short of the amount needed to replace the income of those who cannot work because of their brain injuries, or to provide the institutionalized or in-home care they need.

Radloff's wife, Garland, wants players and their wives to know they don't have to wait for an autopsy to learn if a player has suffered a brain injury, but can get diagnosed through advanced brain scans.

Her husband suffered one of his more devastating blows in September 1988, one that knocked him out cold and yielded the headline: "Falcons Say Radloff Had a Game to Remember, If Only He Could."

The Radloffs, together since his playing days at the University of Georgia and married nearly 28 years, each turned 50 this year. He suffers from dementia and other problems associated with his Chronic Traumatic Encephalopathy, and can no longer hold down his post-football job in real estate.

"It is a brutal way to see somebody die, and to live with it daily and the ups and downs. It's breaking our family's heart," Garland Radloff, a nursing aide who lives with her husband in Hilton Head, S.C., told The Associated Press on Thursday. She and several other wives are also named plaintiffs in the suit.

"If Wayne and I can use our situation to help others," she said, "that is what it's all about."

In a sharp about-face in late 2009, the NFL has encouraged players and their families to cooperate with the Boston University Center for the Study of Traumatic Encephalopathy, which is conducting autopsies on the brains of former athletes -- and finding disturbing evidence of brain damage in football players, boxers and a former NHL player. McMahon has agreed to leave his brain to the center.

The NFL also has issued new concussion guidelines, and ordered that independent physicians determine when a player should return.

The other plaintiffs in the Philadelphia suit are Gerry Feehery, 51, a former Eagles center who played in the league from 1985 to 1989; Mike Furrey, 34, a wide receiver on several teams from 2003 to 2010; and Steve Kiner, 64, a linebacker with the Dallas Cowboys and others from 1970 to 1978.