Parkinson's disease affects two out of every 1,000 people, but since it most often develops after age 50, it is disproportionately represented among seniors. In essence, the older you are, the more likely you are to know someone who has Parkinson's or to have the disease yourself. Although there is no cure for Parkinson's, there are a number of treatments, from medication to deep brain stimulation, that have been effective in controlling its symptoms.
The Dopamine Deficit
At this point, researchers know what happens when someone gets Parkinson's but they don't yet know why. Parkinson's is caused when the brain cells that produce dopamine, a chemical messenger, die or become impaired. Dopamine is sent from one area of the brain to another to produce smooth, purposeful movement. By the time symptoms appear, people have lost 60 percent to 80 percent of these dopamine-producing cells. Recent studies have shown that people with Parkinson's also lose nerve endings that produce norepinephrine, another chemical messenger used by the part of the nervous system that controls automatic functions such as pulse and blood pressure. The loss of norepinephrine helps explain the fatigue and changes in blood pressure regulation associated with the disease.
Promising Avenues for Research
If we can understand the causes of Parkinson's—and there are likely to be several—we will gain the foundation needed to devise more effective treatments. Funding agencies worldwide are devoting hundreds of millions of dollars to this effort, and are concentrating on the following issues:
- Some cases of Parkinson's are hereditary—and scientists are studying the genes responsible to determine how these mutations damage or destroy dopamine-producing cells.
- Scientists believe that exposure to toxins in the environment increases the risk of developing the disease, even among people who are not genetically predisposed to it. Exposure to certain viruses may also increase susceptibility to the disease.
- Several lines of research suggest that mitochondria, the energy-producing components of a cell, may damage dopamine cells by producing a condition known as oxidative stress.
- Other research suggests that the cell's protein disposal system may fail in people with Parkinson's, causing proteins to build up, resulting in cell death.
While the ultimate goal of preventing Parkinson's may take years to achieve, scientists now feel that it is reasonable to hope that we will be able to halt the progression of the disease and restore lost function by the end of the next decade.
Web Resource
For an authoritative overview of the research, visit the Parkinson's disease site at the National Institute of Neurological Disorders and Stroke (NINDS). If you are interested in furthering the development of new Parkinson's treatments, you can visit the Parkinson's disease clinical trials Web site, sponsored by the Michael J. Fox Foundation For Parkinson's Research, NINDS, and other groups.