Alan Alda reveals he has Parkinson's disease

Alan Alda revealed Tuesday that he has been living with Parkinson's disease.

The "M*A*S*H" star appeared on "CBS This Morning" and shared that he was diagnosed three and a half years ago.

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

Alda, 82, said he's going public now because he's been doing a great deal of press lately for his new podcast, "Clear+Vivid with Alan Alda" and he noticed something in the video of himself.

"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," he said.

Parkinson's disease is a "progressive disorder of the nervous system" that primarily affects a patient's movement, according to the Mayo Clinic.

What is Parkinson's disease?

It often begins with a small tremor in the hand or muscle stiffness and gets worse over time.

Alda is best known for his role as Army Captain Hawkeye Pierce on the hit CBS series "M*A*S*H," which ran from 1972 to 1983.

He also hosted the PBS series "Scientific American Frontiers." In 2005, Alda was nominated for a best supporting actor Academy Award for his role in "The Aviator."

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