An experimental drug may be able to reverse the course of Parkinson’s disease in the brain, according to a preliminary report.

An analysis of the brain of a man who took the experimental drug called GDNF (glial cell line-derived neurotrophic factor) showed regrowth of the nerve fibers lost in the progressive degenerative disease.

Researchers say it’s the first time any treatment has been shown to reverse the loss of nerve fibers in Parkinson’s disease. However, safety concerns about the drug will still need to be resolved before it can be considered as a potential treatment for Parkinson’s disease.

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Finding May Renew Interest in Parkinson’s Drug

Parkinson’s disease is a progressive degenerative brain disorder. The disease attacks the cells that make the chemical dopamine. This leads to loss of muscle movement control and disability, as well as tremors that are associated with the disease. Other symptoms include slow movement, stiff muscles, aches, and problems with balance and coordination.

There is no cure for the disease. But medications, which boost dopamine levels, can help manage symptoms.

An improvement in symptoms was seen in a small study of people with Parkinson’s disease who received an injection of the drug into the affected brain region. There is a strong association between the level of disability from the disease and the severity of dopamine loss in the brain.

But a second study was halted after the drug’s maker Amgen withdrew GDNF in part due to safety reasons.

After a 62-year-old man who had participated in the first trial of GDNF died of an unrelated heart attack three months after the treatment stopped, researchers analyzed his brain and reported their findings in the current issue of Nature Medicine.

Because GDNF had been infused into only one side of the brain, researchers say they were able to assess the impact of treatment by comparing the two sides.

The results showed that the drug had stimulated nerve regrowth in the affected region of the brain. Researchers say it’s the first evidence that an infusion of GDNF causes sprouting of dopamine fibers in the brain associated with a reduction in the severity of Parkinson’s disease.

They say the findings may renew interest in GDNF as a potential therapy for Parkinson’s disease.

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By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: Love, S. Nature Medicine, July 2005 online edition; vol 11: pp 703-704. Press release, University of Bristol.