'One of the driving theories behind this study is the possibility that if deep brain stimulation (DBS) therapy was applied early, it may change the progression of the disease, hopefully slowing its advance,' said David Charles, M.D., vice-chair of Neurology and director of the Vanderbilt Movement Disorders Clinic.
Charles says to date there is no current therapy that has been proven to definitely slow the progression of Parkinson's disease. Vanderbilt's Phase 1 clinical trial the first of its kind in the world was years in development and just recently received Food and Drug Administration (FDA) approval to begin.
Parkinson's disease is a chronic, debilitating neuromuscular disease caused by the brain's inability to produce a sufficient amount of the chemical dopamine, which in turn causes nerve cell death leading to impaired function of the body's muscles and movement.
Key symptoms of Parkinson's are tremor (shaking), difficulty with balance, slowness of movement, and rigidity. Other symptoms can include stiff facial expression, shuffling walk, muffled speech and depression.
The National Institutes of Health (NIH) estimates there are as many as 500,000 U.S. citizens with Parkinson's disease, and others, such as the Parkinson's Disease Foundation, say it is more prevalent and may affect as many as 1 million Americans. Estimates are as many as 50,000 new cases are diagnosed each year.
"The theory that applying this therapy early in the course of Parkinson's is that we may see a difference," Charles said.
Vanderbilt researchers hope that by providing a treatment now only offered in late-stage Parkinson's, they can slow the disease's typical progression.
"For this study, which is to measure safety and tolerability of the device in these patients, we'll be using DBS the same way we're treating advanced patients, only much earlier," Charles said.
"We hope to obtain preliminary data that will tell us whether a larger trial is warranted."
The study's protocol calls for a small number of patients to be enrolled and followed over a four-year period.
"If this proves successful we hope to launch a larger trial in the future to test the question of whether this therapy can change or slow the progression of Parkinson's disease," he said.
In 1996 VUMC became one of the first centers in the United States to implant stimulators into the brains of Parkinson's disease patients with advanced symptoms.
DBS is a device which emits a continuous, tunable electrical current, attached to a fine wire, that runs from the unit and is carefully implanted into a specific location deep within the brain. When activated, the DBS device acts on the subthalamic nucleus with electrical stimulation to reduce the symptoms of Parkinson's. In many patients the device produces dramatic results.
Charles and other researchers in Vanderbilt's Departments of Neurology and Neurosurgery have devoted a significant portion of their academic careers to research to find better ways to slow disease progression and improve symptoms of Parkinson's patients. VUMC has been one of the nation's leading centers in Parkinson's research for more than 20 years.
"Our experience has found if patients who receive DBS are properly selected they typically can reduce medicines by about 25 percent. Afterward they can extend the period of time they have a positive impact from their medicine by about 50 percent," Charles said. "So the impact on their overall condition is very good."
Charles said trial participants may help advance the field of research in Parkinson's disease.
"What we learn in this trial will really shape the next step of research on this disease. We are trying to answer a major question of whether receiving this therapy early in the disease may slow progression. If this were to prove true there is no other therapy we can offer today which can do that," he said.