You could call it a musical miracle. Tony Bennett has Alzheimer's Disease and has difficulty holding a conversation, but when it comes time for him to sing, the 95-year-old legendary crooner emerges from the fog of dementia, with the phrasing and gestures fans at any of his past performances would recognize. Anderson Cooper and 60 Minutes cameras were there to witness the astonishing transformation at Bennett's apartment and onstage with Lady Gaga this past summer. The story will be broadcast on 60 Minutes, Sunday, October 3 at 7:30 p.m. ET and 7 p.m. PT on CBS.

The master of the Great American Songbook, Bennett now spends a good deal of his time looking at books and old photos from his life and his seven-decade career. His wife and now full-time caregiver, Susan Benedetto, describes her husband's experience grappling with Alzheimer's.

"Every day is different. Tony late at night, sometimes early in the morning, he's more alert, if I can use that word. So I'll tell him, 'Tone, you're going to be on 60 Minutes.' He's, like, 'Great.' I said, 'You remember that show, 60 Min—' he's like, 'I do.' But in any other given moment, he won't know," Benedetto tells Cooper. "He recognizes me, thank goodness, his children -- we are blessed in a lot of ways. He's very sweet. He doesn't know he has [Alzheimer's]."   

It was an honor to speak with @andersoncooper on @60Minutes about my beloved friend @itstonybennett. The full story is available to watch now on YouTube and at https://t.co/mMnFQ9dWrP ❤️ https://t.co/E5UadegcWU

— Lady Gaga (@ladygaga) October 4, 2021

Bennett was diagnosed in 2017 by Dr. Gayatri Devi, his neurologist. She explains how it's possible that he is still able to sing so well. "The important thing to remember about Alzheimer's is that people respond differently depending on their strengths. In Tony's case, it's his musical memory, his ability to be a performer. Those are an innate and hard-wired part of his brain," Devi says. "So even though he doesn't know what the day might be or where his apartment is, he still can sing the whole repertoire of the American Songbook and move people."

Cooper and cameras first witnessed this at the singer's apartment in New York. Bennett no longer speaks very much, but when he began rehearsing for his concert with his pianist, Lee Musiker, lyrics flowed and his impeccable phrasing and timing were all there. He was Tony Bennett, the legend, again.

Lady Gaga also had been rehearsing with him, in preparation for their August performances at Radio City Music Hall. As she tells Cooper: "Anderson, for the first couple of weeks that I saw Tony since COVID, he called me, 'Sweetheart.' But I wasn't sure he knew who I was."

The two had collaborated musically before, but she says she had to find new ways of communicating with the singer, like keeping her questions to him simple. "For example, if I were to say, 'Tony, would you like to sing 'Love for Sale?'' he'll say, 'Yeah,'" she tells Cooper.  "And if I say, 'Tony, would you like to sing 'Love for Sale' or 'It Don't Mean a Thing if it Ain't Got That Swing?'' he might not have as easy of a response."  

Bennett's oldest son and manager, Danny, was the one who came up with the idea for a two-night concert at Radio City -- with friend and collaborator Lady Gaga -- as a final big curtain call for his dad. The show will be seen on CBS in a future broadcast. Nobody knew whether he would pull off the performance, despite the promising rehearsals. 60 Minutes cameras followed Bennett on opening night to document what happened.