NEW YORK (Jan. 18, 2007) -- Brain damage caused on the football field ultimately led to the suicide of former NFL defensive back Andre Waters, according to a forensic pathologist who studied Waters' brain tissue.

Bennet Omalu of the University of Pittsburgh told The New York Times that Waters' brain tissue resembled that of an 85-year-old man and that there were characteristics of early stage Alzheimer's. Omalu told the newspaper he believed the damage was related to multiple concussions Waters sustained during his 12-year NFL career with the Philadelphia Eagles and Arizona Cardinals.

Waters was 44 when he committed suicide last November.

Omalu said trauma was a significant factor in Waters' brain damage, "no matter how you look at it, distort it, bend it."

The pathologist also told the newspaper the signs of depression that family members described Waters as exhibiting in his final years likely was caused by the brain trauma. Had he lived, Omalu said, the former player would have been fully incapacitated within 10 years.

The Alzheimer's Association Web site reports "there appears to be a strong link between serious head injury and future risk of Alzheimer's." The statement did not distinguish between a single catastrophic trauma and lesser repetitive injuries.

"Whatever its cause, Andre Waters' suicide is a tragic incident and our hearts go out to his family," NFL spokesman Greg Aiello said.

"The subject of concussions is complex. We are devoting substantial resources to independent medical research of current and retired players, strict enforcement of enhanced player safety rules, development and testing of better equipment, and comprehensive medical management of this injury. This work over the past decade has contributed significantly to the understanding of concussions and the advancement of player safety."

Omalu began his research at the request of Chris Nowinski, a former Harvard football player and professional wrestler whose career was ended by multiple concussions. After hearing of Waters' suicide, Nowinski called Waters' sister, Sandra Pinkney, and asked permission to do further investigation on her brother's remains.

Pinkney agreed. In mid-December, Nowinski shipped four pieces of Waters' brain from Florida to Omalu in Pennsylvania.

Nowinski chose Omalu because he had examined the brains of two former Pittsburgh Steelers players who were discovered to have brain trauma after sustaining concussions -- Mike Webster, who suffered brain damage and became homeless before dying of heart failure in 2002, and Terry Long, who killed himself in 2005.

Waters' family said they hope further research will change the way the NFL -- and all athletic organizations -- treat concussions.

"I just want there to be more teaching and for them to take the proper steps as far as treating them," Kwana Pittman, Waters' niece, told the newspaper. "Don't send them back out on those fields. They boost it up in their heads that, you know, 'You tough, you tough."'