Brantley, known as a vicious hitters during his eight-season NFL stint in the 1980s, revealed on HBO's "Real Sports with Bryant Gumbel" that he has the disorder, noting it's so bad that he can't remember his age (60), suffers from hallucinations and hears imaginary sounds. He requires constant assistance from his wife, Mary.
Brantley was first diagnosed with dementia in 2012.
"I am 50 years old. Fifty, turned 50 the 24th of February. And -- is that right?" Scot said in the segment.
Mary responded, "No. He's 60," then adding of him forgetting his age: "It happens all the time."
The HBO segment, called "Unsettled" and which focuses on the NFL's concussion settlement, was to air Tuesday night at 10 p.m. ET.
The Brantleys say that because Scot would appear on local radio segments for a few hours each week in 2012, administrators of the NFL concussion settlement have denied him benefits because they said he had a job. Mary said it was merely to get him out of the house.
"If they were sitting in front of me, I'd say, 'You're a liar, because this is a legitimate claim,'" Mary said. "And I'm sure there are many other people who have been denied."
"Deny -- deny until you die. That's what the players think the NFL is doing and has done. And that's what they think has happened to the many friends that they have and loved that are gone."
Brantley played for the Bucs from 1980 to 1987, after starring at Florida, where he now is a member of the university's Athletic Hall of Fame. He served as the Gators' radio analyst from 1997 to 2003 and with the Bucs from 1999 to 2005. He was diagnosed with severe dementia in 2012.
In addition to his battle with Alzheimer's, he suffered two strokes in 2008, losing nearly all of his sight in his left eye. He underwent heart surgery to repair damage from the strokes.