Music legend Glen Campbell has announced he's suffering from Alzheimer's disease

The country singer announced Wednesday that he has been diagnosed with Alzheimer's disease.

Glen Campbell has been diagnosed with Alzheimer's disease, he reveals in the new issue ofPeople magazine.

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 -- and they want fans to know his condition.

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"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?' "

Here are five things you didn't know about the singer:

1. He's released more than 70 albums and has sold 45 million records. His biggest hits have included "Rhinestone Cowboy" (watch the video below), "Southern Nights," "Galveston," "Wichita Lineman," "By the Time I Get to Phoenix."

2. He was a touring member of the Beach Boys. Campbell filled in for Brian Wilson in 1964-65. He also played guitar on the group's Pet Sounds album and other recordings.

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3. He was chosen by John Wayne to co-star in True Grit. Campbell also has ventured into acting, with Wayne handpicking him to co-star in the 1969 film True Grit. The award earned Campbell a Golden Globe nomination for most promising newcomer. Campbell also sang the title song, which earned him an Oscar nom.

4. He hosted his own variety show. Campbell hosted the 1969-72 show The Glen Campbell Goodtime Hour for CBS. Guests included country stars as well as Stevie Wonder, the Beatles, Lily Tomlin, Anne Murray and Dionne Warwick.

5. He sang a revised version of "Rhinestone Cowboy" at Alice Cooper's Chrismas Pudding concert in December. Campbell changed the lyric "walkin' these streets so long singin' the same old song" to "singin' good old songs." " 'Good old songs' to me sounds better," Campbell told The Republic. "Same old same old same old -- it was like I was complaining. I did change that for that reason to 'singin' some good old songs,' 'cause that's the way I feel now."