'MASH' star Alan Alda reveals he has Parkinson's disease

Loren Roberson

NEW YORK NY- JUNE 07 Alan Alda attends 92Y Presents Alan Alda In Conversation With Neil de Grasse Tyson at Kaufman Concert Hall

Alan Alda, pictured in 2017, has gone public with his Parkinson's disease diagnosis.

"I want to know if there's anything I can do, I wanted to do it before things start to show up", he said.

Alda, 82, told "CBS This Morning" that he'd noticed his thumb twitch during TV appearances the past few weeks and didn't want speculations about his health to become tabloid fodder.

Alda went on to reveal that he first realised something might be wrong after he began acting out his dreams, leading him to ask his doctor for a scan which then led to his diagnosis. Over the years there's been some debate over whether sleep trouble is a complication of Parkinson's or a precursor of the disease - an early warning sign that surfaces well before other symptoms set it. You don't know what it's going to be, but the main thing is, there's stuff you can do, and I've been - you know how I look at it?

Actor Alan Alda arrives for the International Emmy Awards in NY, U.S., November 19, 2012.

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During Alda's long career, he has played a range of roles, from Jack Donaghy's father on "30 Rock" to host of the PBS series "Scientific American Frontiers" for 13 seasons. "It would be kind of ironic if I get quiet about this", Alda said.

Alda confirmed his diagnosis in a tweet Tuesday morning.

"I've acted. I've given talks". I've taken boxing lessons, three times a week. "Maybe I should rephrase that", the star wrote. For example, actor Michael J. Fox was diagnosed with Parkinson's disease in 1991 and has continued to act, including playing a character with Parkinson's disease on The Michael J. Fox Show. Alda said one night he was having a dream where someone was attacking him and he threw a sack of potatoes at the culprit. While it's easy to be "immobilized by fear", he said, there are still plenty of things you can do after being diagnosed.

Scherzer said symptoms of the disease are very treatable, but that the disease itself hasn't been cured.