The actor reveals his dad Chris is in the grip of the devastating condition, which causes severe memory loss and confusion.
However, despite his worsening health, Jackman insists his father is happier than ever - and the star relished the time he got to spend with him during filming for new movie The Wolverine in his native Sydney, Australia last year (12).
He tells America's Parade magazine, ""My dad is fairly well into Alzheimer's now. His short-term memory is pretty much gone. He still recognises me and can talk about the past, and weirdly, he's as happy as I've ever known him, which is wonderful.
""One of the joys of doing The Wolverine was being in Sydney and spending time with him.""