EUGENE, Ore. - Cindy Kokis tucks herself into husband George's arms and gazes up at his face as the two begin a slow, perfectly in-step walk to the tunes of an Argentine tango.

Instructor E. Vivianna Marcel - better known as Ev - calls out instructions.

" 'Leads,' you're walking your 'follows' backward, and we're brushing our knees together," says Marcel, as she moves down the floor with a partnerless student in the class. "This is very good for our balance."

The 54-year-old tango devotee teaches a lot of dance classes - through Lane Community College, the city of Eugene and her own You Can Dance Studio. But this is one of the special ones, a class designed for people with Parkinson's disease and their spouses or companions.

"There's a scientific study that shows that dancing - and especially Argentine tango - really helps people with Parkinson's to improve their balance and generally get around better," Marcel says. "Argentine tango is basically a walking dance, and the way I teach it, they can use the movements in their everyday lives to help them turn corners and go through doorways and respond to the 'freezing of gait' that's common with the disease."

She illustrates that in class by placing chairs on the dance floor so they create an obstacle course of sorts.

"Now, when you see an obstacle and need to turn to avoid it, you start the rocking step back and forth, turning your head to look where you want to go, and ever so slowly you rock around the corner and then start the forward step again," she tells her students. "You can do that in class or anywhere you are."

The study Marcel refers to appeared in the Journal of Neurologic Physical Therapy in December 2007. It cites a study which divided 19 Parkinson's patients into two groups. One took 20 tango classes, and the other did 20 exercise classes for strength and flexibility, both over a three-month period.

Evaluated before and after the classes, all the participants benefited from the physical activity. But compared with the exercise-only group, the tango dancers showed significant improvement in maintaining balance as well as the ability to rise from a seated position, begin walking and navigate more successfully.

Besides the stimulation of basal ganglia - a part of the brain integral to controlling dance movements - as well as neurological structures most negatively affected by Parkinson's disease, the study suggests that dance helps both the social and physical aspects of the condition.

Like Asian-based therapies such as tai chi and qigong, "Social dance in a group setting can enhance motivation in elderly individuals," the study says. "However, tango differs from other complementary movement approaches because it is performed with a partner in a setting that fosters community involvement, it is progressive in nature (because) the participant is always learning and it is performed to music which may engage the participant in addition to serving as an external cue."

Marcel puts it more simply. "I believe Argentine tango is a metaphor for life: You lead, you follow, you do it with mutual respect for your partner, and you do it because it's enjoyable, without the expectation of going anywhere."

As far as tango for people with Parkinson's, "I teach them the same way as I teach anybody else," she says. "This respectful dance is a way to be nourished and touched. It's good for both partners."

Taking up the tango has been both a physical and mental boost for 70-year-old David Kolb, who received his diagnosis of Parkinson's disease more than two years ago. He attends Marcel's class with his wife of 32 years, Anne Niemiec.

He's an avid walker who still enjoys some mountain hiking and who also works out regularly on exercise equipment. But Argentine tango has given him something his other exercising doesn't.

"It does lighten things up, and it's something that's good for (me and my wife) to do together," Kolb says. "We are very pleased with (Marcel's) teaching, and I notice that if I move to music, I feel freer in movement, and the effect lasts for a while after I finish. The tango also helps mood - it makes me more alert."

Like Kolb, George Kokis has always been physically active. And that may be why, after nearly 12 years with the disease, he still has relatively good mobility, his wife says.

"He used to run marathons, and he still takes tai chi, jogs and lifts weights - his method is to just keep on," Cindy Kokis says. "He went to a new neurologist, who said that for a man of 75, he's in good condition, but for a man with Parkinson's disease, he's amazing."

The couple had enjoyed dancing throughout their 42-year marriage, "although George was better than I was - he could always keep a tune and follow the beat. But it appealed to us, and he says it's good to be able to do it again."

Parkinson's disease occurs when nerve cells in the brain that produce dopamine - a chemical that controls coordination of muscles and movement - become damaged or die, according to the National Parkinson Foundation.

Parkinson's affects men and women almost equally, usually after age 65, although 15 percent of the 60,000 cases diagnosed each year are people younger than 50 years old.

A family predisposition occurs in only 5 percent to 10 percent of patients but is clearly familial in less than 1 percent of cases. Progression of the disease varies widely.

Key symptoms of the disease are tremors in limbs at rest, slowness of movement, stiffness and difficulty with balance. Other indications may include cramped handwriting, stiff facial expression, shuffling when walking, muffled speech and depression. There's no cure for the disease, but the foundation urges "maintaining a positive attitude (and) a healthy determination to cope with the illness and sustain the energy, activities and relationships that give life meaning and joy."

Clearly, Marcel and her students - both people living with Parkinson's and their companions - believe Argentine tango is a great way to do it.

"I hope more people with Parkinson's disease will take it up," Cindy Kokis says. "It's just walking - everybody can walk."