Angus Young is painting an inspirational portrait of his retired brother, saying that an ailing Malcolm Young contributed to AC/DC until the very end.

"He kept going as long as he could," Angus told the Pulse of Radio. "I mean, he was still writing until he couldn't do that anymore. You were hoping, you know, that he would get better. The physical side of him, he got great treatment for that, so he's good with all of that. But the mental side has just deteriorated, you know. So he himself said, 'You know, I won't be able to do it anymore.'"

'Rock or Bust,' the band's first album since Malcolm retired in the wake of a dementia diagnosis, is due on Dec. 2. Both Youngs are credited as writers on each of the album's 11 tracks, though Malcolm is currently in a full-time care facility in Australia. He did not perform on 'Rock or Bust.'

AC/DC recently confirmed that Malcolm's symptoms actually began when the group was working on its previous record, 2008's 'Black Ice.' Malcolm was in treatment during the tour that followed, which lasted into 2010. The Youngs' nephew Stevie has since replaced Malcolm, as he did in the late '80s, when Malcolm briefly left to battle alcoholism.

Angus did not mention drummer Phil Rudd -- who was arrested earlier this month on murder-for-hire and drug charges, though the more serious murder-related charge has since been dropped -- during the interview. Shogun's Bob Richards has been filling in.

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