The comic has not been able to perform for the past eight years, since appearing in the movie Lost Highway.
The 64-year-old has long conducted all his interviews by emails because of his illness, which was diagnosed in 1986.
Now his wife Jennifer has revealed in an American TV interview that he can no longer speak
She also said that the infamous 1981 incident when he set fire to himself, previously thought to be an accident while freebasing cocaine, was a suicide bid.
Jennifer said: “No, no, it was not an accident. I think Richard wanted to take his life.”
