Billy Connolly could have had Parkinson's disease for around 10 years before it was diagnosed, his wife has revealed.
Pamela Stephenson, 64, said that she had noticed her husband's hand shaking for many years, but assumed that he had spent too long playing the banjo.
Comedian Billy, 71, has previously told how he was diagnosed with both prostate cancer and Parkinson's disease on the same day.
Now Pamela has told Radio 5 live that the star is "doing incredibly well".
She said: "He's been ill and it was a huge shock for him. For someone who's been healthy his whole life, to suddenly hear that he had two major problems in a week. He had cancer, he's got Parkinson's....
"But thank God his Parkinson's is so mild he will never really have the kind of symptoms that many people associate with Parkinson's, as far as we know."
She added: "He's probably had it for 10 years, so it's very, very slowly progressing... There are different strains of Parkinson's that I'm learning about. "
The Not The Nine O'Clock News star added: "I've actually noticed his hand shaking for many, many years... I used to think he was playing the banjo a bit too much... I think it's been there for a long time."
She said that it had been a difficult time "for the whole family".
"But Billy's one of those people who doesn't like going to the doctor so of course he's going to hear some bad news when he went...," she added.
"He's his curmudgeonly, lovable self and dealt with it the way you would imagine him to deal with it."
Pamela said that her husband did not need medication for Parkinson's because his symptoms were so mild, and while at one time she thought that he might not be able to perform "t here are no problems with his memory".
Billy, who has been given the all-clear following treatment for prostate cancer, has previously described how he received the news that he had cancer and Parkinson's disease on the same day .
"On the Monday I got hearing aids, on the Tuesday I got pills for heartburn which I have to take all the time.
"And on the Wednesday I got news that I had prostate cancer and Parkinson's disease.
"They told me on the phone, they said, 'Look we've had the result and it's cancer'. And I said, 'Oh nobody's ever said that to me before'," he told an ITV documentary.