Alan Alda's battle with Parkinson's written into Ray Donovan role

Alan Alda's battle with Parkinson's disease was written into his role on the hit drama Ray Donovan.

The 83 year old opened up about the illness, which he first revealed last year (18), noting he is often unaware of the physical toll it has taken on him.

"Sometimes I don't know when I'm shaking... I came back from an interview, I said to (my wife) Arlene, 'It's amazing. I must be getting better. I didn't shake at all.' And then I looked at video, and I didn't realise I was shaking," he told the Present Company podcast.

But the veteran screen star is hopeful he will still be able to do what he loves, revealing producers of his series Ray Donovan, which he recently joined for the new season seven, changed his character to reflect his condition.

"When they realised I had Parkinson's, they said, 'You mind if we write that into the script...?'" he recalled. "But now I'm doing scenes where the character I'm playing has a worse tremour than I have, and I have to fake it."

Alda reveals he's drawn inspiration from the late Lionel Barrymore, who continued to work in film despite his deteriorating condition.

He continued, "As long as it doesn't interfere with the audience's focus on the scene and the character, it's just an attribute. Lionel Barrymore acted for 15 or 20 years in a wheelchair... All his characters were wheelchair-bound and nobody thought twice about it."

The veteran screen star is showing no signs of slowing down, appearing as a cut-throat divorce attorney in the critically-acclaimed Marriage Story.

And asked if he ever considered divorce over the course of his 60-year marriage, the star joked, "No, but I'm sure my wife contemplated murder!"