Three former Oakland Raiders have promised their brains to the Concussion Legacy Foundation to honor Ken Stabler, whose brain showed degenerative damage after his death in 2015.

George Atkinson, George Buehler and Art Thoms told the San Jose Mercury News that they will give their brains after death to the Boston-based research center studying chronic traumatic encephalopathy, the disease being linked to repeated blows to the head.

Stabler, who died in July, suffered from Stage 3 CTE, the doctor who examined his brain told ESPN's Outside the Lines.

"He had very substantial lesions. They were widespread. They were very classic," Dr. Ann McKee told OTL. "There was no question about the diagnosis."

Thoms told the Mercury News he was encouraged to make the donation by Stabler's partner, Kim Bush.

"When you see your teammate deteriorate a lot through the end of his life, to see him go out like that, it brings us together," Thoms said.

Three former teammates of Raiders quarterback Ken Stabler say they will donate their brains to a research center studying CTE. AP Photo/Ben Margot

The careers of the four players overlapped in the 1970s with Raiders, including Oakland's first Super Bowl title in 1976.

Atkinson expressed concern about the link between football and brain disease and said he has suffered from memory loss, adding that he quit his job as a Raiders broadcaster because of it.

"I can't remember from yesterday to today half the time," Atkinson told the newspaper.

Thoms said he and other former players weren't sure whether some of their post-career struggles were just due to aging, but "I got to think it is partly from football," he said to the Mercury News.