Just a month after appearing in concert in St. Cloud, country singer Glen Campbell says he's performing his final live concerts and will quit performing for medical reasons.

In an exclusive interview with PEOPLE (via Taste of Country), the Grammy-winning country legend has revealed he has Alzheimer’s Disease.

The 75-year-old ‘Rhinestone Cowboy’ singer and his wife, Kim, say they are going public with his disease now because “he’s hoping to say farewell with a final slate of live performances this fall – and they want his fans to be aware of the musician’s condition.”

Campbell played two shows at St. Cloud's Paramount Theatre just last month.

“Glen is still an awesome guitar player and singer,” Kim told PEOPLE. “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?’”

Campbell was reportedly diagnosed with the disease six months ago.