March 31, 2003 -- Delivering a potent drug directly to the brains of people with Parkinson's disease may be a radical new way to ease the symptoms and stop the progression of the disease. A new study shows the experimental Parkinson's treatment proved safe and effective in its first human trials.
The treatment involves using a pump to supply daily injections of a growth factor, known as glial cell-line derived neurotrophic factor or GDNF, into the brain of people with advanced Parkinson's disease.
The study, an early phase clinical trial designed to test the safety of administering the protein directly to the brain, found the therapy significantly improved motor skills and reduced tremors in five patients with Parkinson's disease. Previously, the technique had only been studied in rats and primates.
"Nobody's ever put a growth factor directly into the brain before," says researcher Clive Svendsen of the University of Wisconsin-Madison, in a news release. "Our main concern was the safety issue, and it is important to keep in mind the limited scope of the trial, but the clinical results we observed were impressive."
The results appear in the March 31 issue of the journal Nature Medicine.
According to the researchers, Parkinson's disease affects about 1.5 million people in the U.S. The disease is caused by the death of brain cells that produce dopamine, which is a chemical that helps control muscle movement.
"GDNF is known to protect dopamine neurons from cell death," Svendsen says. "We know from rat models that GDNF has strong positive effects on dopamine neurons. It can make them produce new processes and function better. It's like plant food. It makes cells healthier."
In the study, five people with advanced forms of Parkinson's disease received a daily injection of 40 micrograms of the protein every day for 18 months.
After a year of treatment, researchers found that the treatment significantly improved the patients' quality of life and also reduced the tremors caused by levodopa, a drug commonly used to treat Parkinson's disease.
No serious side effects were reported, and tests that measured the ability to perform daily living activities showed a 61% improvement. Patients treated with GDNF also showed a 39% improvement in motor skills.
Researchers say brain scans also showed an increase in the brain's ability to store dopamine, which suggests that the treatment either increased the brains ability to process the chemical or stimulated new production of it.
Svendson cautions that these results are only preliminary and based on the experience of only five people with Parkinson's disease. But he says the study suggests larger trials of the treatment are merited.