When AC/DC announced the release of their new album the other day, the good news was offset by some bad: Founding guitarist Malcolm Young was no longer in the band. Seeing that he wasn't involved in the recording of the album due to an undisclosed illness at the time, the news wasn't all that surprising.

According to news reports, Young is being treated for dementia in a Sydney nursing facility. The 61-year-old guitarist was moved into the full-time care facility after suffering a stroke last year.

A family friend told the Sydney Morning Herald, "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. He has a complete loss of short-term memory. His wife, Linda, has put him in full-time care."

According to the Alzheimer's Association, "Dementia is a general term for a decline in mental ability severe enough to interfere with daily life. Memory loss is an example. Alzheimer's is the most common type of dementia." Earlier this year, country music legend Glen Campbell was forced to retire from touring, and was placed by his family into an Alzheimer's care facility, as a result of his battle with the disease.

AC/DC announced their new album, 'Rock or Bust,' on Wednesday, the same day they released a statement about Young's retirement from the band after 41 years. This will be the band's first album without Young, and its first since ‘Black Ice’ debuted at No. 1 in 2008.

While the album isn't due until Dec. 2, a minute-long sample of one of its songs, 'Play Ball,' has shown up in the trailer for MLB's postseason play. The band plans to continue without Young. They'll launch a tour in support of the new record next year with Malcolm's nephew Stevie taking his place on record and onstage.

You Think You Know AC/DC?

More From Ultimate Classic Rock