Malcolm Young, co-founder and former guitarist of Australian hard rock band AC/DC, is suffering from dementia and receiving full-time care for his condition, according to a report in the Sydney Morning Herald. The report comes days after the band announced that Young was retiring.

Young co-founded the band with his brother Angus in 1973, and the two had been fixtures in the band ever since. Malcolm never got as much attention as his flashier brother, but the two were absolutely crucial in defining the band’s sound both live and in the studio. Malcolm officially took a leave of absence from AC/DC a few months ago, and there was rampant (but unconfirmed) speculation as to the status of the guitarist’s health.

Earlier this week, AC/DC announced that they would be releasing a new album, Rock Or Bust, which would be their first album without Malcolm in the band. Malcolm’s nephew Stephen has been brought in as a replacement.