Pro Football Hall of Famers Tony Dorsett and Joe DeLamielleure, and former NFL All-Pro Leonard Marshall have been diagnosed as having signs of chronic traumatic encephalopathy, a degenerative condition many scientists say is caused by head trauma and linked to depression and dementia, doctors have told "Outside the Lines."

The three former stars underwent brain scans and clinical evaluations over the past three months at UCLA, as did an unidentified ex-player whose test results are not yet available. Last year, UCLA tested five other former players and diagnosed all five as having signs of CTE, marking the first time doctors found signs of the crippling disease in living former players.

CTE is indicated by a buildup of tau, an abnormal protein that strangles brain cells in areas that control memory, emotions and other functions. Autopsies of more than 50 ex-NFL players, including Hall of Famer Mike Webster and perennial All-Pro Junior Seau, who committed suicide last year, found such tau concentrations.

Researchers told "Outside the Lines" they notified Dorsett by phone Monday that they had diagnosed him as having signs of the neurological disease. Dorsett, in an appearance Wednesday afternoon on ESPN's "Dan LeBatard Is Highly Questionable" show acknowledged he had been tested at UCLA and received results: "I'm not going to say too much more about it ... I'm trying to be proactive rather than reactive."

Two weeks ago, upon arriving in California for his evaluation and brain scan at UCLA, Dorsett described to "Outside the Lines" the symptoms that compelled him to seek testing: memory loss, depression and thoughts of suicide.

The former Cowboys running back, now 59, said that when he took his Oct. 21 flight from Dallas to Los Angeles for testing, he repeatedly struggled to remember why he was aboard the plane and where he was going. Such episodes, he said, are commonplace when he travels.

Dorsett said he also gets lost when he drives his two youngest daughters, ages 15 and 10, to their soccer and volleyball games. "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."

The 1976 Heisman Trophy winner and eighth all-time leading NFL rusher said he has trouble controlling his emotions and is prone to outbursts at his wife and daughters.

"It's painful, man, for my daughters to say they're scared of me." After a long pause, he tearfully reiterated, "It's painful."

Dorsett said doctors have told him he is clinically depressed.

"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."