Honolulu, Hawaii – Levodopa is the most effective treatment for Parkinson’s disease, but some laboratory studies have raised concern that it may hasten disease progression. Those fears appear to have been laid to rest by the clinical results of a large double-blind study – the Elldopa Trial by the Parkinson Study Group -- to be presented during the 55th Annual Meeting of the American Academy of Neurology in Honolulu, March 29-April 5. However, contradictory neuroimaging results from the same study may keep the question alive.
Three hundred sixty-one untreated patients with early Parkinson’s disease were given either a placebo or one of three doses of levodopa for 40 weeks. Patients were tested before and two weeks after treatment with the Unified Parkinson’s Disease Rating Scale (UPDRS), the standard measure of disease-related clinical disability. After the two-week washout, patients who had received levodopa scored better on the UPDRS than those who received placebo, and those receiving the highest dose did best. Other measures showed similar results, including Quality of Life and Activities of Daily Living scores.
According to Stanley Fahn, MD, "The clinical outcomes did not show that levodopa hastened worsening of the disease, but rather that levodopa may have slowed the rate of progression, although the 2-week washout design would not have detected the presence of a more sustained symptomatic benefit rather than a slowing of the disease progression." In addition to being the lead study author, Fahn is the current president of the American Academy of Neurology.
Before-and-after neuroimaging studies, conducted in a subset of patients, indicated a 4 to 7 percent decline in dopamine-producing cells in levodopa-treated patients, versus only a 1 percent decline in placebo-treated patients. "In contrast to the clinical results, the imaging substudy suggests that levodopa caused a more rapid decline in the nigrostriatal nerve terminals," said Fahn of the cells that release dopamine in the brain. "These contradictory findings warrant further investigation into the effect of levodopa on Parkinson’s disease, and a pharmacologic effect by levodopa on this type of imaging study needs to be investigated."
The study was supported by the National Institutes of Health and the Department of Defense.
The American Academy of Neurology, an association of more than 19,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis.
For more information about the American Academy of Neurology, visit www.aan.com.
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Editor's Notes: Dr. Fahn will present his research at 2:00 p.m. on Tues., April 1 in Room 310 of the Hawaii Convention Center (HCC).
Interviews with Dr. Fahn may be arranged by visiting or calling the AAN Press Room (Room 327 of the HCC).
All listed times are for Hawaiian-Aleutian Standard Time (HT).