Alan Alda has Parkinson's disease: Here are 5 things you should know

Ken Alltucker | USA TODAY

Show Caption Hide Caption Alan Alda's been living with Parkinson's disease for years The 82-year-old "M*A*S*H" actor revealed that he'd been diagnosed three and a half years ago.

Alan Alda, the award-winning actor and star of the long-running comedy-drama M*A*S*H, revealed that he has Parkinson’s disease.

The Emmy and Golden Globe award-winning actor on Tuesday shared his diagnosis on "CBS This Morning" after he noticed his thumb twitch during TV interviews. He said he has lived a full life since being diagnosed 3½ years ago and wanted to share his story with others.

Alda is among about 1 million Americans with Parkinson’s disease, an incurable nervous system disorder that also afflicts celebrities such as actor Michael J. Fox, singer Linda Ronstadt and former president George H.W. Bush.

What is Parkinson’s disease?

It is a nervous system disorder that slows movement and often causes tremors such as a hand shaking or finger twitching. A person may move more slowly, walk with a shuffle or gait in one leg, speak softly, slur words or lose sense of smell. The disease is progressive, which means symptoms typically worsen over time.

Kelly Mills, an assistant professor of neurology at Johns Hopkins Hospital in Baltimore, said that up to 30 percent of Parkinson's patients never have tremors. But he said that the slow movement may shorten a stride, make it difficult get up from a chair or limit hand dexterity,

"The hallmark symptom is slowness of movement," Mills said. "Movement is slow and small. That is the core symptom, and it is not always visible to others."

What causes the disease?

Parkinson's disease is triggered by a loss of neurons in the the brain. When these brain neurons die, it creates a lack of lack of dopamine in the brain, leading to abnormal brain activity and the disease's symptoms, according to Mayo Clinic.

It's unknown what causes the disease. Only 10 to 15 percent of cases have a known link to a single defective gene that can span generations of a family. Other risk factors include age, exposure to toxins and gender – and men are more likely to be diagnosed than women, according to the Parkinson's Foundation.

More recent research points to a combination of factors such as genetic risk and environmental factors.

More: A former mayor is using boxing to fight his Parkinson's

What are some treatments?

Although the disease is incurable, people can live for decades and effectively manage symptoms with drug treatments, according to doctors who treat the disease.

There are a range of drugs, medical devices and other treatments such as exercise used to treat the disease. A commonly prescribed drug is levodopa, which helps synthesize dopamine in the brain. It is often paired with another drug, carbidopa, to reduce nausea.

Another class of drug, known as dopamine agonists, mimics the effects of dopamine rather than replacing the drug in the brain, according to Mayo Clinic.

Drugs can effectively control movement for Parkinson's patients for years, and the bigger challenge is often taking care of nonmovement issues such as depression or sleep disruption, said Michael Okun, a University of Florida neurologist.

"The nonmotor features of Parkinson's disease are much more disabling than the motor features," said Okun, who also serves as medical director of Parkinson's Foundation, an advocacy group. "With treatments, patients with Parkinson's disease can do very well and live good, meaningful and happy lives."

Are there other treatments?

For patients with more advanced forms of the disease, some find relief through an operation called deep-brain stimulation.

The technology involves surgically placing a small, pacemaker-like device under a person's collarbone and electrodes in a person's brain. Tiny pulses are delivered from a battery-powered neurotransmitter through a small wire that runs beneath the skin to block the activity that triggers the tremors.

The technology has been used when medication no longer is effective and stopping or slowing involuntary movement.

Other, less-invasive options include medication-infusion pumps, Mills said.

Living with Parkinson's disease

In addition to drugs and deep-brain stimulation, doctors and therapists recommend a range of strategies to live fully with the movement disorder.

Patients often receive speech and occupational therapy to learn how to adapt to everyday tasks such as dressing, eating and bathing. Okun said his Florida clinic will borrow another program that involves acting techniques to train patients to project their voices or control hand movements.

Mills, of Johns Hopkins, said recent research also shows that moderate cardiovascular exercise may play a role in slowing the disease.

"Often the symptoms can be managed effectively," Mills said. "There are a lot of reasons to be optimistic about the ability of current therapies to control the disease."