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Glen Campbell's career didn't end when he revealed he had Alzheimer's disease in 2011. He went on to record an album, play more than 150 concerts to promote it, star in a documentary about life with Alzheimer's and win awards for its leading song.

Now 78 and in the late stages of the disease, Campbell's wife will attend Sunday's Academy Awards in his stead. Tim McGraw is set to perform Campbell's nominated song, "I'm Not Gonna Miss You," which won a Grammy Award earlier this month.

"He's such a great singer and Glen always loved him," Campbell's wife, Kim Campbell, said of McGraw. "It's going to be an emotional night to hear it performed."

Campbell's nomination is one of two Oscar nods related to Alzheimer's disease this year. Julianne Moore is favored to win the best actress award for her portrayal of an early-onset Alzheimer's patient in "Still Alice."

Campbell's nominated song plays at the conclusion of the documentary, "Glen Campbell... I'll Be Me." Married for 32 years, Kim Campbell appears often in the film, which follows the couple as the entertainer performs around the world after announcing his Alzheimer's diagnosis. His wife worried about how fans would respond to the concerts, and how Campbell would react to the spotlight.

"Maybe fans are not going to want to come see somebody play who has Alzheimer's," she feared. "They may not want to remember Glen that way. They might think it's too depressing."

But the opposite happened. The shows sold out and Campbell shone. Though his memory was fading, his music was intact.

"It was miraculous," Kim Campbell said. "Off stage, he had Alzheimer's. But on stage, it was like Glen is back!"

The performances were so well-received, and he so enjoyed his time on stage, that they extended what was to be a five-week tour into nearly two years, the documentary crew following along.

They captured Glen Campbell writing his Oscar-nominated song with producer Julian Raymond, as well as Campbell's sense of humor around his diagnosis. Asked about his experience with Alzheimer's, Campbell responds, "It's fine. I just don't remember anything!"

"It's a very uplifting film, and funny. It's about love and family, having a good attitude and Glen's music," Kim Campbell said.

Watching it was comforting, she said, like "being wrapped in a warm blanket of love."

But his condition has since declined. He can no longer communicate, nor understand spoken words.

"It's really difficult because it's such a contrast between (the film) and his mental capabilities today," she said. He has fleeting moments of lucidity when they can see each other clearly that she says "pierce your soul."

While she has told him about his Oscar bid, she's not sure he understands.

"What I'm hoping is if I could just put one in his hand," she said, "maybe he'll remember the three times he sang at the Oscars."

Win or lose, the family is deeply grateful for the nomination because they hope it will bring awareness to Alzheimer's disease, Kim Campbell said.

"It's a dream come true," she said. "I mean, what a way to cap off Glen's career."