Tony Bennett is battling Alzheimer's disease

Tony Bennett's family has revealed that for the last four years, the legendary crooner, who's 94, has been battling Alzheimer's disease.

Breaking their silence in AARP The Magazine, the family explained that Bennett's long-awaited sequel to his Grammy-winning 2014 album with Lady Gaga, "Cheek to Cheek," is going to be released this spring, but because of his condition, Bennett cannot participate in any interviews.

That's why, they said, they decided to go public with the diagnosis.

When Bennett's son and manager Danny asked Lady Gaga how she felt about the family revealing Bennett's condition, Danny noted that she said, "Absolutely. It's just another gift he can give to the world." The forthcoming album was recorded between 2018 and 2020.

Even after Bennett's diagnosis, he was still able to tour and perform a 90-minute set so well that nobody suspected anything was wrong, his family revealed to AARP.

His last live show was in March 2020, due to the COVID-19 pandemic, but his doctor recommended that the star continue to sing, because it's so helpful in managing his illness, the hallmark of which is increasing dementia and memory challenges. In fact, Bennett's longtime pianist comes to his apartment twice a week and runs through his 90-minute set with him.

Amazingly, even though Bennett's family said he is often unaware of where he is and cannot recognize everyday objects, he can sing all the songs perfectly. He also still recognizes his family members, according to his wife Susan.

In a statement to "Good Morning America," Danny Bennett shared, "Managing my father for the last 40 years has been a privilege and an amazing journey. He never ceases to inspire me with his passion and dedication to all that life has to offer. The last four years has been no exception."

"He continues to sing and stay fit on a daily basis," his statement continued. "I speak for the whole family in thanking his wonderful wife Susan for all the support and love she has given to him. Our wish is that by openly sharing his challenges with Alzheimer’s that we will give hope to all that face this condition and will help end the stigma surrounding this disease. Above all else, we want to be able to help raise awareness, advocate for advancing new therapies and one day soon, finding a cure. "

Bennett's neurologist told AARP The Magazine, "He is doing so many things, at 94, that many people without dementia cannot do. He really is the symbol of hope for someone with a cognitive disorder."

In fact, Susan, told the magazine, "Singing is everything to him ... If he ever stops singing, that's when we'll know ... hopefully he'll just go to sleep one night and that will be that."

"He's not the old Tony anymore,” she added, heartbreakingly. "But when he sings, he's the old Tony."