Country music veteran Glen Campbell says he is "tired of lying" about his battle with Alzheimer's disease.
The 76-year-old American crooner, known for hits such as Wichita Lineman and Rhinestone Cowboy, last month cancelled a planned tour of Australia and New Zealand.
The tour Down Under with Kenny Rogers was meant to have taken place this month.
In an interview with the Seven Network, he said he wanted to tell the public about the illness he was diagnosed with in early 2011.
"I got tired of lying. I shouldn't be lying. It's silly," he said from his Malibu home.
"Always tell the truth - the way you see it, the way you hear it."
His wife of 30 years, Kim Campbell, said most days were "pretty good, lately", but there were challenges.
"Every now and then if he doesn't get enough rest, he gets a little spacey," she said.
His daughter Ashley Campbell, who is also a country music singer, said music was "therapeutic" for her father.
"I've noticed he does better mentally when he's getting to play music, play guitar and sing," she said.
Campbell sung happy birthday to his wife, referring to her as "my darling", but appeared to have trouble recalling her name.
"I think I know your name. What is it?," he said.
But the man who has a solo career spanning 50 years recognised a picture of himself with Elvis Presley.
"He had more charisma in his little finger than anybody ... he was just awesome," he said.