BOSTON (AP) — Dave Duerson, a former NFL player who committed suicide in February, had “moderately advanced” brain damage related to blows to the head, according to the researcher who made the diagnosis.

“It’s indisputable” that Duerson had chronic traumatic encephalopathy, a disorder linked to repeated brain trauma, Dr. Ann McKee said Monday.

The findings were announced as part of an effort conducted by the Center for the Study of Traumatic Encephalopathy at Boston University’s School of Medicine. The CSTE Brain Bank has the brains of more than 70 athletes and military veterans, with football players comprising more than half of the athletes.

Duerson played safety in the NFL for 11 seasons, seven with the Chicago Bears, and was chosen for four Pro Bowls before retiring in 1993.

“Dave Duerson had classic pathology of CTE and no evidence of any other disease,” McKee said, “and he has severe involvement of all the (brain) structures that affect things like judgment, inhibition, impulse control, mood and memory.”

The body of Duerson, who was 50, was found in Sunny Isles Beach, Fla., on Feb. 17. He left a note asking that his brain be given to the NFL’s Brain Bank. He shot himself in the chest, “presumably” to preserve his brain for study, said Chris Nowinski, co-director of the CSTE.

Duerson’s case was “moderately advanced,” said McKee, also a CSTE co-director. “The likelihood is that if he hadn’t had the CTE, he wouldn’t have developed those symptoms that he was experiencing at the end of his life and perhaps he wouldn’t have been compelled to end his life.”

Dr. Robert Cantu, another CSTE co-director, said that such results normally are published first, but the Duerson family wanted them released earlier. Duerson’s former wife, daughter and three sons attended the news conference.

“We have been given the gift of closure,” said his son, Tregg. “We accept this gift with great humility, as we are mindful of other families that have lost loved ones and still bear the burden of unanswered questions.”

CSTE is a collaboration between Boston University Medical School and the Sports Legacy Institute, headed by Nowinski. The center has been aggressively researching head trauma in sports, and has received a $1 million gift from the NFL, which it has pushed for better treatment of concussions.

Duerson was a third-round draft choice by the Bears out of Notre Dame in 1983. He played safety on the team that won the Super Bowl in the 1985 season. He moved to the New York Giants for one season in 1990 then played his last three NFL years with the Phoenix Cardinals.

He went to another Super Bowl with the Giants.

Nowinski said “the latest version of the NFL’s guidelines (on concussions) are well thought out. And, I think, with the state of the science today, it’s about the best we can do.”

But he said the problem starts much earlier, in youth football.

“The 6-year-olds are playing the same games as the pros when we know that their brains are far more susceptible to this damage,” he said. “My next focus is how do we change youth football so that a kid doesn’t show up in the NFL with 10,000 hits to their head already?”

Copyright 2011 The Associated Press.