Media playback is unsupported on your device Media caption Glen Campbell performing These Days

US country music star Glen Campbell has been diagnosed with Alzheimer's disease, the 75-year-old and his wife have told People magazine.

Kim Campbell said if her husband "flubs a lyric or gets confused on stage", she wanted fans to know the reason.

Mr Campbell plans to retire from the music industry later this year with a series of farewell concerts.

The singer, diagnosed six months ago, is known for hits like Rhinestone Cowboy and Wichita Lineman.

"I still love making music, and I still love performing for my fans. I'd like to thank them for sticking with me through thick and thin," Mr Campbell said.

The Grammy Award winner, who will launch his final tour in October, said he was suffering from short-term memory loss for years, prior to his diagnosis.