*THE QUESTION: The involuntary tremors and other movement problems experienced by people with Parkinson's disease often can be kept in check with medication. But levodopa, considered the gold standard of treatment, doesn't help everyone. Might a drug used to treat people with epilepsy offer relief?

*THIS STUDY involved 347 adults for whom levodopa did not relieve Parkinson's disease symptoms. They were randomly assigned to take zonisamide (25, 50 or 100 milligrams) or a placebo daily, along with levodopa. After three months, more than 30 percent of the people taking zonisamide showed improvement of 30 percent or more on standardized rating scales for Parkinson's symptoms, compared with 22 percent of the placebo group. Those taking the 50-milligram dose registered the most improvement (39 percent). Most people taking the drug reported side effects, usually drowsiness, apathy, weight loss or constipation.

*WHO MAY BE AFFECTED BY THESE FINDINGS? People with Parkinson's disease, a progressive neurological disease for which there is no cure. It occurs most often in people 60 and older, and in men slightly more frequently than in women.

*CAVEATS: The average dose of levodopa taken by participants was less than the dose most often used to treat Parkinson's; it remains unclear whether the results would vary if higher doses of levodopa were taken. Zonisamide was tested only as an adjunct treatment. Long-term effects were not determined. The study was funded by Dainippon Sumitomo Pharma, the Japanese company that discovered zonisamide.

*FIND THIS STUDY: Jan. 2 issue of Neurology; abstract available at www.neurology.org.

*LEARN MORE ABOUT Parkinson's disease at www.ninds.nih.gov/disorders and www.parkinson.org.

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.