Six years ago today, on June 22, 2011, Glen Campbell fans received sad news: They learned that the iconic singer had been diagnosed with Alzheimer's disease.

Campbell had been quietly battling Alzheimer's for a few years before he revealed his diagnosis. After the disease progressed to the point where fans might notice that Campbell was struggling, the artist and his family decided to go public with the devastating news.

“Glen is still an awesome guitar player and singer,” his wife, Kim Campbell, told People magazine at the time. “But if he flubs a lyric or gets confused onstage, I wouldn’t want people to think, ‘What’s the matter with him? Is he drunk?'"

Campbell continued with his plans to embark on a farewell tour even after his Alzheimer's diagnosis. He performed his final show on Nov. 30, 2012.

“He functions the best on stage,” Kim Campbell explained in 2012. “I think it’s where he feels the most comfortable, because everything is the same for him on the stage. He knows where he is, where the band is, where the audience is and what he’s supposed to do.”

While he was still able to communicate, the "Rhinestone Cowboy" singer became an advocate for funding the prevention and cure of the disease. To that end, Campbell traveled to Capitol Hill in 2012, along with his wife and children Ashley, Cal and Shannon.

A Photographic Look Back Through Glen Campbell's Career

Sadly, by early 2014, Campbell's Alzheimer's had progressed to the point where it was no longer safe for him to remain in his home, and he was moved to a facility to receive full-time care.

“You have to watch him every single second. He’s up all hours of the night and wanders,” Kim Campbell shared at the time. “He’ll pick up knives, and sometimes he won’t want to relinquish it.”

“[It can be dangerous] with all the household appliances and dish soap liquid and olive oil,” added daughter Ashley Campbell. “He’ll drink anything … if you lose concentration for a second, he could hurt himself.”

In the fall of 2015, Campbell returned home briefly, although the transition wasn't without its struggles: “He punched me in the eye, gave me a black eye — had a black eye for two weeks,” his wife told Broadway’s Electric Barnyard. “He can be combative … so that’s an ongoing challenge."

Campbell relocated to a new care facility a few months later.

“I always wanted to bring him home and give it another try because I miss him so terribly,” Kim Campbell said, but “it was just more than I could handle. He’s the sweetest person in the world, but he becomes combative when you try to change his clothes or bathe him. It really wasn’t the best situation.”

Campbell's Alzheimer's disease has advanced to Stage 7, the final stage of the disease. Although he has lost the ability to communicate, and most people with Stage 7 are believed to be near death, Campbell's wife says that he is doing as well as can be expected.

“He still understands the universal language of smiles and kisses, and he enjoys food," she saysadding, "He cannot play guitar anymore. I don’t even know if he knows what it’s for. But our children come and play for him. It’s hard to tell if he’s responding to it much. Sometimes he’ll listen, and sometimes he’s distracted. He’s in his own world right now.”

In 2014, a documentary, Glen Campbell: I'll Be Me, about Campbell's extraordinary life and career, as well as his disease, was released. The film's theme song, "I'm Not Gonna Miss You," co-written and sung by Campbell, won a Grammy for Best Country Song, and both the movie and its soundtrack received numerous other accolades. I'll Be Me was also a finalist for the prestigious Peabody Awards.

Glen Campbell Through the Years