Bobby Womack says he has been diagnosed with early signs of Alzheimer's disease at age 68.
"The doctor said, 'You have signs of Alzheimer's,'" the American soul singer told the BBC.
"He said, 'It's not bad yet, but it's going to get worse.' How can I not remember songs that I wrote? That's frustrating."
Womack is a prostate and colon cancer survivor who also recently suffered pneumonia twice, as well as collapsed lungs.
He earned great reviews last year for "The Bravest Man in the Universe," his first album of new material in 18 years. He was inducted into the Rock 'n' Roll Hall of Fame in 2009.
"I don't feel together yet because negative things come in my mind and it's hard for me to remember sometimes," Womack told the BBC. "The most embarrassing thing was when we were getting ready to announce [his album's producer] Damon [Albarn] and I can't remember his last name. That's so embarrassing."