The Grammy winner, 75, and his wife, Kim, say they are sharing the news because he hopes to give a series of goodbye concerts this fall -- in conjunction with a final album, "Ghost on the Canvas," to be released Aug. 30 -- and they want fans to know his condition.
"Glen is still an awesome guitar player and singer," says Kim. "But if he flubs a lyric or gets confused on stage, I wouldn't want people to think, 'What's the matter with him? Is he drunk?' "
The singer, whose "Rhinestone Cowboy" topped the charts in 1975, has been suffering from short-term memory loss in recent years. He was diagnosed with Alzheimer's disease six months ago.
He says the lyrics to his new song, "A Better Place" -- which include, "I need the ones I love Lord/More and more each day" -- are very personal given his diagnosis.
"I still love making music," says Campbell. "And I still love performing for my fans. I'd like to thank them for sticking with me through thick and thin."