BINGHAMTON, NY -- A Binghamton University researcher will receive $1.33 million from the National Institutes of Health to support Parkinson's research that will focus not only on the treatment of the disease but also in the side effects of treatment.
"Parkinson's disease patients have trouble with movement," said Christopher Bishop, assistant professor of psychology. "They move more slowly. They have rigidity in their limbs. They have balance problems and tremors."
The cardinal symptoms are a result of a deficit of dopamine in the brain. Dopamine is a neurotransmitter that's essential for movement; it also plays an important role in behavior, cognition and sleep. In Parkinson's patients, neurons in the brain that make dopamine die. Scientists still aren't sure why; genetic factors are believed to play only a small role.
This deficit of dopamine can be reversed with treatment using a compound called L-DOPA, which has been the gold standard in Parkinson's treatment for about 50 years. The brain converts L-DOPA into dopamine, which is why it's an effective replacement therapy for patients. For five to 10 years, this treatment works well. "The problem," Bishop explained, "is that Parkinson's is a progressive disease. You lose more and more of these neurons as time goes on, so therapeutically, doses of L-DOPA must increase."
While that works for some people, many patients suffer troubling side effects as the dosage increases. "By year 10," Bishop said, "as many as 90 percent of patients will start to suffer from motor fluctuations and something called L-DOPA-induced dyskinesia. So you go from a state of no treatment where you're not moving well, to a state where the drug is working well and you're moving fluidly, to a point where L-DOPA doses are very high and you're producing these abnormal, involuntary movements."
The excessive movements patients display aren't a result of the Parkinson's disease, but rather a symptom of the chronic L-DOPA. And patients can't simply stop taking L-DOPA; if they do, they face a nearly "frozen" life with incredibly limited ability to move.
Bishop and his colleagues at Wayne State University's medical school and the Veterans Administration hospital in Chicago hope to find a way to reduce dyskinesia and suppress these movements. There are very few treatments available, in part because how dyskinesia develops is still a mystery.
"We are beginning to believe that dyskinesia is actually the inability to suppress motor memories as a result of the drug's stimulation," Bishop said.
One possible treatment relates to glutamate, a neurotransmitter in the brain that can play a role in these memory processes, helping to lay down new pathways for motor memories. The five-year grant from the National Institute for Neurological Disorders and Stroke will allow Bishop and his team to study serotonin compounds that reduce glutamate following L-DOPA treatment. Bishop's work has also been supported by the American Parkinson's Disease Association.
According to Bishop, Parkinson's is an increasingly urgent medical concern. Roughly 1 million people in the United States have Parkinson's; 50,000 more Americans are diagnosed with the disease each year.
"That's only going to increase as our population ages," Bishop said. "This is not something that's going away.
|Contact: Gail Glover|