Since AC/DC announced that the band's co-founder Malcolm Young will be leaving indefinitely due to unspecified health reasons, after a career spanning over four decades as the rhythm guitarist, many fans of the Aussi rock group have speculated on the nature of his illness.

Malcolm Young [L] with the rest of AC/DC

Earlier last week, new reports surfaced that claimed Young was forced to call time on his rock career because he is suffering with dementia and has moved into full-time care in a nursing home facility, this unfortunate diagnosis has now been confirmed by one of the musician's family members.

"Malcolm is suffering from dementia and the family thanks you for respecting their privacy," his family said Tuesday (Sept 30th) in a statement to People magazine.

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In April, the 61 year-old musician initially left AC/DC because he was struggling with an undisclosed illness, and the they asked that people respect the privacy of Malcolm and his family at this difficult time. "Malcolm would like to thank the group's diehard legions of fans worldwide for their never-ending love and support," a statement read at the time.

In December, AC/DC will release their 15th studio album 'Rock or Bust,' which will be their first record that won't feature Young in the group's 41 year-career together.

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"Unfortunately, due to the nature of Malcolm's condition, he will not be returning to the band," a recent statement said. "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."

AC/DC have sold more than 200 million albums worldwide.