West, 81, has been married to Fawlty Towers actress Prunella Scales, best known for her role as Sybil, for 52 years.
He told Piers Morgan’s Life Stories: “Well, the sad thing is that you just watch the gradual disappearance of the person that you knew and loved and were very close to.
“There’s a lot of her left, and we still enjoy life and there are a lot of things that Pru is able to enjoy and we’re able to do together.”
She was diagnosed 15 years ago, and Mr West says initially he knew there was something wrong with her, but didn’t realise what it was.
Mr West said the most difficult part of her illness was “communication”, adding: “When we’ve been to a concert, or a play, or a film, there’s nothing very much we can say about it afterwards because Pru will have a fairly hazy memory.
“It develops very gradually, if you live from day to day then it’s manageable, but it’s when you start thinking about the past: ‘What a shame she can’t do that anymore, or she can’t appreciate that anymore or we can’t talk about that anymore.’ Then it’s sad.”
West was previously married to actress Jacqueline Boyer, and had a daughter named Juliet with her. However, after five years of marriage they separated and he lost contact with Juliet until reconciling with her 10 years ago.
He said: “I feel guilty about it but I also feel a sorrow that I’ve missed the time that fathers should spend with their daughters, and be showing them things about life, and introducing them to things.”
He went on to marry Scales and they have two children together — Samuel, an actor, and Joe who is a teacher, translator, and computer programmer.
West’s career has spanned a successful arena stretching from theatre, to TV and film. While he has starred in both Coronation Street and EastEnders, it was his role in the TV show Edward VII that was his big break at the age of 40. His EastEnders character Stan Carter made his last on-screen appearance in April, when viewers saw him die of cancer.
Talking about “dying on camera” West said: “Well I’ve died on TV a few times now. As you get older it gets slightly more worrying.”