AC/DC's Malcolm Young is believed to be ''suffering from dementia''.

The 61-year-old guitarist and founding member of the rock band - whose retirement was announced last Wednesday (24.09.14) - has reportedly been admitted to Lulworth House, a full-time care home in Sydney.

Malcolm's wife, Linda, is believed to have made the decision to move him after the care he needed at home became too difficult.

A statement released by AC/DC's labels, Albert Music and Sony, earlier this week confirmed Malcolm's departure from the band.

It read: ''Unfortunately due to the nature of Malcolm's illness, he will not be rejoining the band.''

Meanwhile, the labels also confirmed that Malcolm's nephew, Stevie Young, would replace him as rhythm guitarist and that the rock band would be touring next year.

The statement read: ''AC/DC will undertake a world tour in support of 'Rock or Bust' in 2015. Stevie Young, nephew of founding members Angus and Malcolm Young, plays rhythm guitar on 'Rock or Bust' and will accompany the band on tour.''