A Wednesday report by ESPN.com's William Weinbaum and Steve Delsohn reveals the development after the retired superstars had undergone brain scans and clinical evaluations at UCLA over the past three months.
Another unidentified player underwent tests, but his results have yet to be released.
The report includes information from the UCLA doctors conducting the testing on the former football players, which they discussed on ESPN's Outside the Lines television program on Monday. It also explains the methods of testing:
Researchers involved in the UCLA testing say their brain scan uses a radioactive marker to identify the signs of CTE in the living, as was done with the eight former players. The research team, in affiliation with a company named TauMark, includes forensic pathologist Bennet Omalu, who discovered CTE; UCLA psychiatrist Gary Small and pharmacologist Jorge Barrio; and neurosurgeon Julian Bailes, co-director of the NorthShore Neurological Institute in Evanston, Ill.
CTE is "a degenerative condition caused by head trauma and is linked to depression and dementia," as defined by Weinbaum and Delsohn. The abnormal protein known as tau is the source for the disease's devastation, as it "strangles brain cells in areas that control memory, emotions and other functions."
Dorsett, a Hall of Famer who ran for more than 12,000 yards for the Dallas Cowboys, told Outside the Lines that he had sought testing because he was experiencing memory loss, depression and thoughts of suicide.
Weinbaum and Delsohn provide more insight into the 59-year-old Dorsett's condition. When he set out to travel from Dallas to Los Angeles on Oct. 21 for additional testing, he had trouble remembering why he was on the plane. It was something Dorsett intimated was common whenever he took trips.
The 1976 Heisman Trophy winner specified other instances in which the symptoms of CTE have impacted how he interacts with his family. When driving his daughters to soccer and volleyball games, he finds himself lost at times.
"I've got to take them to places that I've been going to for many, many, many years, and then I don't know how to get there," said Dorsett.
Dorsett also touched on the physical and mental anguish he has experienced.
"I've thought about crazy stuff, sort of like, 'Why do I need to continue going through this?'" he said. "I'm too smart of a person, I like to think, to take my life, but it's crossed my mind," said Dorsett.
DeLamielleure was never diagnosed with a concussion in his 13-year playing career, but now at the age of 62, he explains that he has unprovoked mood swings and sad thoughts, similar to what Dorsett feels.
"When I sit still for any length of time, I get depressed for no reason," said DeLamielleure. "I have CTE, let's see what the heck we can do about it."
These findings are monumental and fortify efforts to diagnose CTE in the living. More than 50 former NFL players have been found to have CTE in autopsies, per the report.
The three players named in the report who underwent testing at UCLA are also part of a class-action lawsuit against the NFL featuring 4,500 plaintiffs. It alleges that the league covered up a link between playing football and brain damage, and is currently being settled for $765 million.
Within the report, Dorsett says that he is trying to be proactive rather than reactive, and hopes to slow down or cut off the symptoms of CTE to live out a healthy remainder of his life.
DeLamielleure was a six-time Pro Bowler at offensive guard for the Buffalo Bills and Cleveland Browns and played from 1973 to 1985. He is a Hall of Famer like Dorsett.
Marshall is a two-time All-Pro and two-time Super Bowl champion. He was drafted by the New York Giants in the second round of the 1983 NFL draft and played 10 seasons with the G-Men. He also played one year with the New York Jets and one year with the Washington Redskins, finishing his career with 83.5 sacks in 177 games.