Although symptoms of Parkinson’s disease often improve when the drug levodopa is given, brain scan results suggest that the drug hastens progression of the disease, according to a report in The New England Journal of Medicine.

Given these conflicting findings, the long-term effects of levodopa on the disease remain unclear, lead author Dr. Stanley Fahn, from Columbia University in New York, and colleagues note.

The researchers evaluated 361 patients with early Parkinson’s disease who were treated with levodopa at one of three doses or with inactive “placebo” for 40 weeks. The main outcome measure was the extent to which symptoms worsened during treatment, but a subgroup of patients was also evaluated with brain scans.

Parkinson’s symptoms worsened to a lesser extent in patients who received levodopa, at any dose, than in those who received placebo. In contrast, brain scanning in 116 patients showed that patients treated with levodopa lost more critical nerve cells than those who received placebo.

Although the long-term effects of levodopa are still uncertain, the authors say that “we can assure both patients with early Parkinson’s disease and their physicians that, from a clinical perspective, our study did not find that levodopa hastens” disease progression.

“For the present, until more evidence is available, we recommend customizing the dose of levodopa to the needs of the individual patient on the basis of the clinical response and the profile of adverse events,” they conclude.

SOURCE: The New England Journal of Medicine, December 2004.