Alan Alda announced Tuesday that he's been, and he says there are a few things he wants people to know about the condition. For one thing, it's hardly slowing him down.
"I'm doing great. You might be surprised to hear that," Alda said as he revealed the news of his diagnosis on "CBS This Morning." "The reason that I want to talk about it in public is that I was diagnosed three and a half years ago, and I've had a full life since then."
The award-winning actor, known for his iconic role in "M*A*S*H," has continued performing, launched a new podcast, and kept up his work at the Alda Center for Communicating Science at Stony Brook University in New York. Recently, he realized he could no longer keep his condition private.
"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."
Alda, 82, says he asked his doctor for a scan that led to his diagnosis after reading an article about Parkinson's in The New York Times and recognizing an early sign of it in himself.
"If you act out your dreams, there's a good chance that might be a very early symptom... where nothing else shows," he explained. "By acting out your dreams, I mean I was having a dream where someone was attacking me and I threw a sack of potatoes at them, and what I was really doing was throwing a pillow at my wife."
Months later, he started noticing "a little twitch in my thumb," but says he's refusing to let fear limit his life.
"This is a disease that's different for almost everybody who has it. There are some common symptoms, but mostly everybody's different and each day is different from the next," he said.
Alda joins other prominent figures who've spoken openly about having Parkinson's, including actor, who revealed his diagnosis in 1998 and started the Michael J. Fox Foundation to help search for a treatments and a cure, and singer , who announced earlier this year that he was retiring from touring because his recent diagnosis of Parkinson's disease had made extensive travel difficult.
Here are answers to some common questions about Parkinson's disease.
What is Parkinson's disease?
Parkinson's disease is a disorder of the central nervous system that affects movement, often causing tremors.
Estimates vary, but about 50,000 people are diagnosed with Parkinson's in the United States each year and about half a million people have the disease, according to the National Institutes for Health.
While a tremor is perhaps the most recognizable symptom of Parkinson's, the disease can also cause stiffness, slowed movement and speech changes.
What causes Parkinson's disease?
The cause of Parkinson's is unknown but scientists believe several factors play a role, including genetics, environmental triggers and other health conditions.
According to the Mayo Clinic, researchers have identified specific genetic mutations associated with, though these are rare unless many family members are affected by the disease.
The presence of Lewy bodies -- clumps of specific abnormal proteins -- also appear to be markers of Parkinson's disease. Scientists are working to better understand their relationship to the disease.
Additionally, research has also shown that exposure to toxins, including herbicides and pesticides, may slightly increase the risk of Parkinson's.
Men are also more likely to develop Parkinson's than women. People typically develop the disease around 60 or older.
How is Parkinson's treated?
Currently, there is no known cure for Parkinson's disease, but a variety of medications can provide relief from symptoms.
Parkinson's is a both a chronic and progressive disease, meaning it persists over a long period of time and symptoms grow worse over time. Some people become severely disabled, while others may experience only minor motor disruptions. At this time, doctors are unable to predict which symptoms will affect an individual or how intense they will be throughout a person's life.