Alan Alda the Good Fight

CBS All-Access

Alan Alda revealed today that he has Parkinson's disease and was first diagnosed more than three years ago.

The 82-year-old Emmy-winning actor, who broke out as Captain Hawkeye Pierce on "M*A*S*H" shared the news on "CBS This Morning."

"I've had a full life since then. I've acted, I've given talks, I help at the Alda Center for Communicating Science at Stony Brook. I started this new podcast," he explained.

"And I noticed that – I had been on television a lot in the last couple of weeks talking about the new podcast – and I could see my thumb twitch in some shots, and I thought, it's probably only a matter of time before somebody does a story about this from a sad point of view, but that's not where I am."

Parkinson's is a nervous system disorder than can cause tremors and twitching. Other high-profile celebrities with the disease is Michael J. Fox, who was diagnosed in 1982, and Neil Diamond, who shared his diagnosis earlier this year.

Alda asked his doctor for a scan after noticing he was acting out his dreams, an early symptom of Parkinson's.

He revealed that he asked for a scan after reading an article that acting out your dreams, something he was doing, could be a very early symptom of the disease. Months later, he noticed the twitch in his thumb.

“In the very beginning to be immobilized by fear and to think the worst thing has happened to you, it hasn’t happened to you. You still have things you can do," he said, noting that he takes weekly boxing lessons.

Alda has continued to be busy with acting in the last several years. He most recently guest starred on CBS All-Access' "The Good Fight."