'M.A.S.H.' star Alan Alda reveals he has Parkinson's disease

In this April 26, 2013 file photo, actor Alan Alda listens during an interview at Stony Brook University, on New York's Long Island. (AP Photo/Richard Drew)

NEW YORK -- Actor Alan Alda says he has Parkinson's disease.

Appearing Tuesday on "CBS This Morning," the former "M.A.S.H." star said he was diagnosed with the neurodegenerative disorder three and a half years ago. Alda says he expects a tabloid will soon publish a story about his diagnosis.

The 82-year-old says he's not angry and considers it a challenge. Alda says he has acted and given talks since then. He says he could see his thumb twitch in a recent podcast and thought someone would soon do a sad story.

Alda says revealing his diagnosis might be helpful to others with Parkinson's that there are things they can do.

Alda played a senator who ran for president on "The West Wing" and he also hosted "Scientific American Frontiers" on PBS.