A drug commonly prescribed to treat dementia may be the key to reducing the number of debilitating falls for people with Parkinson's disease.

A study published in The Lancet Neurology found that Parkinson's patients who were given the drug rivastigmine (Exelon) in oral form were 45 percent less likely to fall compared to those who took a placebo. Rivastigmine is used to treat mild to moderate Alzheimer's, and for mild to moderate dementia related to Parkinson's.

Falls are a common problem for people with Parkinson's disease, which causes tremors, rigidity of the limbs and trunk, and impaired balance. About 70 percent will fall at least once a year, and more than a third will suffer repeated falls causing fractures, broken bones, and hospital admissions.

"With the degeneration of dopamine producing nerve cells, people with Parkinson's often have issues with unsteadiness when walking," said head researcher Dr. Emily Henderson of the U.K.'s University of Bristol. "As part of the condition, they also have lower levels of acetylcholine, a chemical which helps us to concentrate — making it extremely difficult to pay attention to walking."

Henderson and her colleagues studied 130 people with Parkinson's who had fallen in the past year. Half the group were given rivastigmine capsules and the other half a placebo for eight months.

"We already know that rivastigmine works to treat dementia by preventing the breakdown of acetylcholine, however our study shows for the first time that it can also improve regularity of walking, speed, and balance. This is a real breakthrough in reducing the risk of falls for people with Parkinson's."

About 60,000 Americans are diagnosed with Parkinson's every year, and thousands more remain undiagnosed. It's considered a disease of aging, since the onset of symptoms occurs around the age of 60 and the risk rises with advancing age.

"This trial shows that there may be drugs already available, being used for other purposes, that can be tested to help treat Parkinson's," said Dr. Arthur Roach, Director of Research at Parkinson's UK, which funded the study. "This takes us a step closer to improving the quality of life and finding better treatments for people with Parkinson's."