Diane Cook's 65th birthday was a milestone for her, but not because of her age. That was the day she was diagnosed with Parkinson's disease.

"I was stunned," she said, adding that even though she had had symptoms for four years before being diagnosed, the news was still a surprise.

That day, she could not muster the courage to learn more about what was in store for her. But the next day she pored over the Internet to learn about the disease. She quickly discovered that it would continue to get worse, and that there was no cure.

Parkinson's disease, often associated with boxer Muhammad Ali and actor Michael J. Fox, affects 1 million Americans, according to the National Parkinson Foundation.

While the exact causes largely remain a mystery, doctors know that the condition arises from the degeneration of a specific area of the brain involved in movement. As a result, those with Parkinson's experience tremors, rigidity, slowness in moving, and difficulty with balancing and walking.

Parkinson's eventually leads to mood disorders and dementia. The complications associated with the condition are the 14th largest cause of death in the United States, according to the U.S. Centers for Disease Control and Prevention.

Not only is there no cure for Parkinson's, but many patients have no way of knowing how quickly their symptoms will progress.

"We all worry about how rapidly we'll lose our abilities," Cook said. "The uncertainty is very frustrating."

A new study from UCLA may help. Researchers have found two variants on a gene already known to be associated with Parkinson's that may be able to predict how quickly patients with the condition will deteriorate. The study found that patients with one particular variant were four times as likely to have rapid decline of motor function. Those patients having both of the variants studied were even more likely to see their disease progress more quickly.

The information is important, as patients who have more severe motor disease tend to die sooner.

Read more:
Gene Predicts Parkinson's Progression