Study finds Parkinson's disease hot spots

People with Parkinson's disease are more likely to be found in the Northeast and Midwest than other parts of the country, and whites and Hispanics are more likely to have it than blacks and Asians.

Those are two of the key findings of a new study on the debilitating neurological disorder by researchers at Washington University in St. Louis.

"Finding clusters in the Midwest and the Northeast is particularly exciting," said Dr. Allison Wright Willis, assistant professor of neurology at the Washington University School of Medicine. "These are the two regions of the country most involved in metal processing and agriculture, and chemicals used in these fields are the strongest potential environmental risk factors for Parkinson's disease that we've identified so far."

Willis is the lead author of the study, which appears online in the journal Neuroepidemiology. The research was based on data from 36 million Medicare recipients.

The study found that Parkinson's was strongly prevalent in seniors in Pasco and Hernando counties but less so in those in Pinellas and Hillsborough.

Genetic factors can explain only a small percent of Parkinson's cases, Willis believes. Environmental factors such as prolonged exposures to agricultural herbicides and insecticides and metals such as copper, manganese and lead, are likely more common contributors.

Willis is now trying to account for the study's finding that blacks and Asians are roughly half as likely to have Parkinson's as whites and Hispanics.

"It could be that those with Asian or African ancestry have genes that help protect them from exposure to environmental factors that cause Parkinson's disease or they may have fewer exposures to those factors."

Willis and her colleagues are now planning to studies how exposure to single or combined environmental factors influences Parkinson's disease risk.

Funding from the National Institute for Environmental Health Science, the National Institute of Neurological Disorders and Stroke and the National Center for Research Resources supported the research by Willis and her team.