Australia's Sydney Morning Herald is reporting that former AC/DC guitarist Malcolm Young has dementia and is being treated in a nursing home in Sydney.
The facility is believed to be Lulworth House in Elizabeth Bay.
"If you were in the room with [Malcolm Young] and walked out, then came back in one minute later, he wouldn't remember who you are," a Young family connection told the newspaper. "He has a complete loss of short-term memory. His wife, Linda, has put him in full-time care."
Michael Browning, AC/DC's former manager, told AAP: "I have friends that are still involved, and they keep me posted, so I have known for a little while. I think [Young's illness] came on very suddenly. It's shocking. It's terrible. Sadly for AC/DC, they're losing their creator, their mentor. He's the genius behind the band."
Young, 61, reportedly suffered a stroke last year and did not participate in the recording sessions for AC/DC's new studio album, Rock Or Bust, which will be released December 2.
It has been announced that Malcolm won't be returning to the group due to ill health. His replacement is Angus and Malcolm Young's nephew, Stevie Young. Stevie played on the new CD, which was recorded at the Warehouse Studio in Vancouver, British Columbia, Canada with producer Brendan O’Brien and mixer Mike Fraser.