I've just read in the newspaper that he's entering rehab for two months after becoming addicted to painkillers he takes for a damaged knee. He's also developed a dependency on alcohol. The article in the press says he also became depressed due to problems trying to start a family.
Seemingly co-workers in BGT were concerned enough about him to say something and following another operation on his knee a few days ago he'll now go into rehab.
I really appreciate the talents of Ant n Dec and I hope he's better soon.