Sir Billy Connolly is willing to be a "guinea pig" in a bid to find a cure for Parkinson's disease.
The 75-year-old comedian has been battling with the incurable condition, which causes parts of the brain to become progressively damaged over years, since mid-2013 and has admitted he's been in contact with stem cell scientists at Harvard University about using him to advance their research and, hopefully in the long run, discover a cure for the condition.
Speaking in an extract taken from a book, published by The Scotsman, he said: "I've spoken to guys working on it at Harvard and told them I'll be a guinea pig for them. I think they are going to take me up on that."
It comes just weeks after his close pal Sir Michael Parkinson said he was saddened during a recent meeting in New York with the funnyman when Billy failed to recognise him.
He explained: "The sadness of Billy now is that wonderful brain is dulled.
"I saw him recently - he's now living in America - and it was very sad, because I was presenting him with a prize at an award ceremony.
"We had an awkward dinner together, because I wasn't quite sure if he knew who I was or not. We were walking out after the presentation to go down and have our picture taken, and he turned to me and put his hand on my shoulders.
"He wasn't sure where [the dinner] was or what context at all."
Michael, 83, and Billy have been close friends for years, with the latter making a number of appearances on his talk show 'Parkinson', which ran from 1971 to 1982 and from 1998 to 2007, and he found the experience with his old pal deeply upsetting.
He added: "And to know someone as long as I knew and loved Billy... it was an awful thing to contemplate, that that had been taken from him in a sense.
'He was just a genius and the best thing that happened to me on the show."
Billy - who was diagnosed with prostate cancer in 2013 but underwent successful surgery to remove the disease - previously admitted he has contemplated suicide on numerous occasions since being diagnosed with Parkinson's disease.
Asked in 2016 if he has ever thought about ending his life, he said: "Yeah sometimes I give it a bit of thought when I'm in bed. I think, 'Well this is forever, this isn't going to get better, it's going to get worse.' But then I try and change my mind and I try and meditate and move away from it sideways."