Singer Tony Bennett has revealed he has Alzheimer's disease.
The 94-year-old's diagnosis was publicised by AARP, a US campaign group on age-related issues.
He was diagnosed with the disease, which affects the memory and cognitive functions, in 2016, AARP said.
The American singer wrote on Twitter: "Life is a gift – even with Alzheimer's."
Alongside a link to the article announcing his diagnosis, he added: "Thank you to [my wife] Susan and my family for their support, and AARP The Magazine for telling my story."
Neurologist Gayatri Devi, who diagnosed Bennett, told AARP the singer has "an amazingly versatile brain".
She said he has some "cognitive issues, but multiple other areas of his brain are still resilient and functioning well".
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Ms Devi added: "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."
Ms Devi said she urged Bennett's family to keep him singing as it "stimulated his brain in a significant way".
However, the I Left My Heart In San Francisco singer's condition is worsening, according to AARP.
"Bennett, who first diagnosed in 2016, has so far been spared the disorientation that can prompt patients to wander from home, as well as the episodes of terror, rage or depression that can accompany Alzheimer's' frightening detachment from reality; and, indeed, he might never develop these symptoms," the article stated.
"But there was little doubt that the disease had progressed. Even his increasingly rare moments of clarity and awareness reveal the depths of his debility."
Bennett has collaborated with artists including Lady Gaga and Amy Winehouse.
In the spring he is to release a follow-up to the album Cheek To Cheek, which he released with Gaga in 2014, according to AARP.
Bennett has won 19 Grammys, the most recent of which came in 2018 when he was 91.
His first Grammy wins came at the fourth annual show in 1962 for record of the year and best solo vocal performance for I Left My Heart In San Francisco.
In 2001, the New Yorker won a lifetime achievement award.
Sky News has approached Bennett for comment.