Parkinson's research scientists looking for the cause of Parkinson's disease continue to search for possible environmental factors, such as toxins that may trigger the disorder, and to study genetic factors to determine what role defective genes play in causing the disease. Although Parkinson's disease is rarely directly inherited, some people may be genetically more or less susceptible to developing it. Other scientists are working to develop new protective drugs that can delay, prevent, or reverse the disease.

 

Scientists are also looking for clues to the cause of Parkinson's disease by studying malfunctions in the structures called "dopamine transporters," which carry dopamine in and out of the synapse (the narrow gap between nerve cells). For example, one research group recently found an age-related decrease in the concentration of dopamine transporters in healthy human nerve cells taken from areas of the brain damaged by Parkinson's. This decline in transporter concentration means that any further threat to the remaining dopamine transporters could result in Parkinson's disease.

 

The search for more effective Parkinson's disease medications is likely to be aided by the recent isolation of at least five individual brain receptors for dopamine. New information about the unique effects of each individual dopamine receptor on different brain areas has led to new treatment theories and clinical trials.

 

Scientists are also studying new methods for delivering dopamine to critical areas in the brain. Investigators, using an animal model of the disease, implanted tiny dopamine-containing particles into brain regions affected by the disease. They found that such implants can partially improve the movement problems exhibited by these animals. These results suggest that similar techniques may one day work for people with Parkinson's disease.

 

Additional controlled-release formulas of Parkinson's disease medications are under investigation, as are implantable pumps that give a continuous supply of levodopa to help people who have problems with fluctuating levels of response. Another promising Parkinson's disease treatment method involves implanting capsules containing dopamine-producing cells into the brain. The capsules are surrounded by a biologically inert (non-reactive) membrane that lets the drug pass through at a timed rate.