Alzheimer's Drug May Help with Parkinson's Too

NEW YORK (Reuters Health) - Donepezil (Aricept), a drug used for treating people with Alzheimer's disease, may also improve the thinking ability of Parkinson's patients who have developed dementia -- a common problem with this disorder -- new research suggests.

However, the results show that while donepezil is a safe and well-tolerated treatment for Parkinson's-related dementia, it only provides modest improvements in mental capacity.

Given the drug's effects in Alzheimer's patients, it was thought that donepezil might also benefit Parkinson's patients. However, the drug does have certain chemical properties that could, in theory, worsen the movement problems commonly seen with Parkinson's disease.

Dr. B. Ravina, from the National Institutes of Health in Bethesda, and colleagues compared the effects of donepezil and placebo in 22 Parkinson's patients with dementia. The subjects were treated with donepezil or placebo each day for 10 weeks and then, after a 6-week "washout" period, with the other agent for 10 weeks.

In the study, which is reported in the Journal of Neurology, Neurosurgery, and Psychiatry, donepezil was not significantly better than inactive "placebo" at improving thinking ability on a variety of standard tests. However, on two tests, donepezil did outperform placebo.

Moreover, there was no evidence that the drug aggravated any Parkinson's symptoms as feared.

"Additional research is needed to determine whether all (drugs like donepezil) are of equal efficacy in this setting, the duration of benefit to be expected, and the interaction with (other) drugs commonly used in this patient population," Dr. Jeffrey L. Cummings, from the University of California at Los Angeles, notes in a related editorial.

SOURCE: Journal of Neurology, Neurosurgery, and Psychiatry, June 2005.