At the Mark Morris Dance Center in Brooklyn, some patients with Parkinson's disease are finding relief from their debilitating symptoms and maintaining their quality of life -- by dancing.
"This class gives people a chance to think of themselves as dancers rather than as patients," said David Leventhal, who has been teaching dance classes for Parkinson's patients for 11 years.
Parkinson's is a chronic movement disorder that worsens over time and is often characterized by tremors, slow movements, stiff limbs and impaired balance. The disease affects as many as 1 million Americans, according to the Parkinson's Disease Foundation.
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"It slows people down. It affects their coordination," Dr. Claire Henchcliffe, a neurologist and director of the Parkinson's Disease & Movement Disorders Institute at the New York-Presbyterian Hospital/Weill Cornell Medical Center, told NBC News' Chelsea Clinton. "There's actually a loss of rhythm."
Learning complex dance moves such as ballet or tango can counter that.
"You'll often see people with Parkinson's when they get up to move, they'll hesitate as they go to initiate the first few steps of walking," Henchcliffe said. "But I think the music of dance, and the movements of dance, can provide an external go signal that actually helps people to overcome that lack of signal, that lack of cue."
Exercise alters the way that people use dopamine, a neurotransmitter critical for movement, said Henchcliffe. Those with Parkinson's disease often do not produce adequate dopamine. "So even if we don't make enough dopamine, exercise helps us make more of what we've got," Henchcliffe said.
Charles Tobey, a Parkinson's patient, has been coming to the dance classes at Mark Morris for about six years. "I feel great when I come here and feel like I have something that makes me feel really good about myself," he said.
Similar classes are offered in more than 100 other communities and nine different countries.
"People are dancing with a freedom that they couldn't imagine," said artistic director Mark Morris. "It's not a trick and it's not magic. But it seems a little bit magical."
NBC News' Craig Stanley contributed to this report.