AC/DC are forging ahead despite two of their longtime members dealing with serious issues. Guitarist Malcolm Young officially stepped away from the group earlier this year after it was revealed that he was dealing with dementia. The status of drummer Phil Rudd is not as clear, as the musician was arrested earlier this month of 'threatening to kill,' drug possession and murder-for-hire charges. Though the murder-for-hire charge was eventually dropped, there's still plenty of legal issues on the table for Rudd.

In a new interview with Rolling Stone, guitarist Angus Young addresses both his brother's condition as well as where the band stands with Rudd. During the interview, Angus revealed that Malcolm Young's health issues actually predated the making of the band's upcoming 'Rock or Bust' album, with the guitarist showing signs of memory lapses and concentration issues dating back to the 'Black Ice' album cycle.

"It's something that had actually been happening for a long time," says Angus. "[It] had surfaced even before the last project … [Malcolm] was still capable of knowing what he wanted to do. I said to him, 'Do you want to go through with what we're doing?' and he said, 'S--t, yeah.' Young says his brother liked to finish what he started.

Angus revealed that Young had already been receiving treatment during the band's touring of 'Black Ice' between 2008 and 2010, adding, "He got good help, good medical care. [He had] to relearn a lot of things … which was very strange for him. But he was always a confident guy and we made it work."

For 'Rock or Bust,' Malcolm was replaced by Stevie Young, a nephew to the Young brothers. Regarding the new album, singer Brian Johnson says, "It was awful and great at the same time. Angus must have felt strange playing these tunes without Malcolm ... [Stevie] worked his socks off to make sure he was on the money."

As for Rudd, Young reiterated some of his recent comments about the drummer's reliability. He recalls that the musician was 10 days late for the 'Rock or Bust' sessions, explaining, "One minute he was coming, then he wasn't, then he was. We're not a band that likes to wait around." Young says the band was one day away from moving on without the drummer when Rudd finally showed and completed his parts.

Speaking about the future with Rudd, Young admits, "The drum situation is a question mark, but we will definitely be out there … But our problems had begun even before the situation he's in now. And our thing was we were going forward." The guitarist concludes that Rudd's arrest was "a big blow," but adds that the band is committed to touring and promoting their new album.

Read the full interview at RollingStone.com.

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