US actor Alan Alda was forced to rely on himself from a very young age - because he couldn't trust his schizophrenic mother.

Alda, who recounts childhood with a paranoid schizophrenic parent in his new book NEVER HAVE YOUR DOG STUFFED, AND OTHER THINGS I HAVE LEARNED, also describes what it was like for his father - most shockingly in the opening line: "My mother didn't try to stab my father until I was six."

The M*A*S*H star says, "(The illness) was very difficult, very embarrassing for him. One time, DAVID SELZNICK came over to the apartment and she said, 'So, you're David Selznick,' and he said, 'Yes I am.' And she said, 'Sure, sure you are,' and started to accuse him of lying."

On another occasion Alda's mother was convinced that someone had bugged her home.

He explains, "With schizophrenia the hallucinations are completely real. It would be like someone coming in now and saying, 'You know, I've watched you for an hour-and-a-half and you think you're talking to someone, but there's no one there.'

"Either one of us would say, 'How dare you, I'm sane, I know there's somebody there. You're trying to make me doubt my own sanity.' You wouldn't take it and neither would she. They were absolutely real to her."

Alda had to learn to trust his own observations - which even from the age of six were more reliable than what his mother would tell him.

"My life depended on being able to observe well because she was telling me crazy things, and one of them could be dangerous to me.

"I had to be my own parent."