CHICAGO -- The family of former Chicago Bears player Dave Duerson filed a wrongful death suit against the NFL on Thursday, claiming the league didn't do enough to prevent or treat the concussions that severely damaged his brain before he killed himself last year.

The suit was filed in Chicago on behalf of Duerson's son, Tregg, and three other children. Duerson died on Feb. 17, 2011, of a self-inflicted gunshot wound to the chest at his home in Sunny Isles Beach, Fla.

Dave Duerson's family alleges the league didn't do enough to prevent or treat the concussions that severely damaged his brain before he killed himself. Jonathan Daniel/Getty Images

Duerson's family wants to know more about the NFL's handling of concussions during his career, according to his son.

"If they knowingly failed to inform and implement proper safety concussion procedures, then their indifference was the epitome of injustice," Tregg Duerson said at a news conference announcing the lawsuit. "The inactions of the past inevitably led to the demise and death of my father.

The lawsuit accuses the NFL of negligently causing the brain damage that led Duerson to take his own life at the age of 50 by not warning him of the negative effects of concussions. Attorney Thomas Demetrio, who is representing Duerson's family, said the NFL should have been a leader in educating current and former players about head injuries.

"They not only dropped the ball, they maintained until current times that there was no connection between playing football, receiving concussions and brain damage," Demetrio said. "That's wrong."

The NFL said in a statement that it had not yet seen the lawsuit.

"Dave Duerson was an outstanding football player and citizen who made so many positive contributions but unfortunately encountered serious personal challenges later in his life," the NFL said. "We sympathize with the Duerson family and continue to be saddened by this tragedy."

The suit also names helmet maker Riddell Inc., alleging that the helmets didn't adequately protect players from concussions. The company declined comment.

A native of Muncie, Ind., Duerson was a third-round draft pick by the Bears in 1983 out of Notre Dame and played 11 seasons in the NFL before retiring in 1993. He won Super Bowls with the 1985 Bears and 1990 Giants, and played in four Pro Bowls.

The lawsuit was filed less than a week after nearly a dozen former NFL players living in Louisiana sued the NFL over their own concussions.

Several former New Orleans Saints players are among the 11 ex-players named as plaintiffs in the class-action lawsuit filed Friday in federal court in New Orleans. The lawsuit says each of them has developed mental or physical problems from concussions or concussion-like symptoms. Several suits blaming the NFL for concussion-related dementia and brain disease already have been consolidated in Philadelphia.

Duerson had at least 10 concussions in his NFL career, according to his family, and lost consciousness during some. He left notes for his family asking that his brain be donated to science, and researchers at the Center for the Study of Traumatic Encephalopathy at Boston University's School of Medicine concluded he had "moderately advanced" brain damage and CTE related to blows to the head. The damage started to manifest itself about 10 years before his death, his son said, though the changes were gradual.

"It was slow deterioration, day after day," Tregg Duerson said. "You can see his mannerisms change toward the end of his life."

The lawsuit says brain damage affected his judgment, inhibition and impulse control.

"My dad donating his brain as his last plea, we feel as though we're taking that to the next level," Tregg Duerson said. "We believe that he would've wanted us to pursue this, and because of that belief, we feel obligated to do so."