A New Way to Treat Parkinson's Disease
Experimental Parkinson's Disease Treatment Restores Function
April 28, 2003 -- An experimental Parkinson's disease treatment may help preserve brain function and stop the involuntary movements associated with current Parkinson's disease treatments. A new study found the treatment safely eased symptoms and improved the quality of life in people whose disease was poorly controlled by other Parkinson's disease treatments.
The new therapy involves delivering an infusion of a naturally produced growth factor known as glial cell line-derived neurotrophic factor (GDNF) directly into the brain. Previous studies have shown that the treatment improved motor function in animals, but this was the first study to test the treatment's safety in humans.
The results were presented this week at the 71st Annual Meeting of the American Association of Neurological Surgeons in San Diego.
More than 1 million Americans suffer from Parkinson's disease, a progressive disease in which certain brain cells stop producing a chemical called dopamine that acts as messenger in the brain. The loss of dopamine causes a loss of brain function, shaking, stiff muscles, slow movement, and difficulty with walking and balance.
Most currently available Parkinson's disease treatments involve replacing the lost dopamine with medications or surgical treatments, such as deep brain stimulation or transplantation of dopamine cells into the brain. But researchers say none of these approaches actually stops the continual loss of the brain's remaining dopamine cells.
Researchers say GDNF is thought to be important in developing and maintaining these dopamine cells, which are lost in Parkinson's disease.
In this experimental treatment, a catheter delivers GDNF directly to an area of the brain that is deprived of dopamine in Parkinson's disease. A continuous supply of GDNF is provided by a pump, which is surgically implanted in the patient's abdomen and refilled on a monthly basis.
This phase 1 clinical trial of GDNF therapy examined the safety of the treatment in five people with Parkinson's disease. Researchers found the side effects of GDNF infusion were relatively minor, but higher doses produced intermittent tingling in the neck and shoulders. The dosage was reduced after three months of treatment and these side effects improved.
After one year of treatment, the study found motor function improved by 39% and the patients' ability to carry out normal daily activities improved by 61%.
Involuntary movements, which are commonly caused by dopamine replacement therapy, were reduced by 64% in the four out of five patients who said they were a problem.
Brain scans showed that there was also an increase in dopamine storage in the area of the brain where GDNF was infused, which researchers say suggests a direct effect of GDNF on dopamine function.
In addition, the study showed an unexpected effect of the treatment: Three patients who had lost their senses of smell and taste because of Parkinson's disease recovered these senses after a few weeks of GDNF treatment.
Now that the GDNF infusion has been shown safe in humans, researchers say the next step will be broader and double-blinded clinical trials to compare the effectiveness of this investigational treatment with other currently available Parkinson's disease treatments.
"Our hope is that this study will prompt further research into the use of other [growth factors ] which may have the potential to slow down the progression or promote recovery of neurons in other neurodegenerative disorders including Alzheimer's disease and Huntington's disease," says researcher Nikunj K. Patel, MD.