Study Suggests Parkinson’s More Common in Hispanics
6/5/2003
Parkinson’s, Thu June 5, 2003 05:36 PM ET (Reuters) By Martin F. Downs
NEW YORK (Reuters Health) - New U.S. statistics on Parkinson's disease suggest that Hispanics have higher rates of the disease compared with people in other ethnic groups. This study is unique from previous research in that it directly assessed the rate of Parkinson's disease in Hispanics, said Dr. Stephen Van Den Eeden.
An earlier study conducted in Upper Manhattan, New York, looked at blacks, whites, and "other" racial and ethnic groups. The "others" were largely Hispanic, but there were no detailed data on them. "We found that Hispanics appear to have the highest rates of Parkinson's disease," Van Den Eeden told Reuters Health. Van Den Eeden and colleagues in the research division of the Kaiser Permanente Medical Program studied 588 people newly diagnosed with Parkinson's in 1994 and1995.
Kaiser Permanente is a health management organization (HMO) that serves the San Francisco bay area of northern California. The patients in the study were all HMO members. Hispanics had the highest rate at 16.6 cases per 100,000, followed by non-Hispanic whites at 13.6 per 100,000. Asians had a rate of 11.3 per 100,000 followed by blacks, who had a rate of 10.2 per 100,000, according to the report in the American Journal of Epidemiology.
These findings contradict the Manhattan study, which found that blacks had the highest rate of Parkinson's disease. The rate in that study, which looked at 83 Parkinson's patients, was more than twice as high as that seen in the new study. As was expected, the disease was most common in older people. Only 0.5 percent of cases in the study were diagnosed before age 40, while about three percent were diagnosed before age 50. More than 60 percent of the Parkinson's patients in the study were diagnosed between the ages of 65 and 79.
The researchers also report that in all groups except Asians, men had rates about twice as high as women. Rates were slightly lower in Asian men. The size of the study is notable because the largest previous study looked at only 154 patients. "It's a difficult disease to capture in a defined population," Van Den Eeden said. To do a large study in a particular area requires all healthcare providers in the area to report every case, which can be surprisingly difficult, Van Den Eeden said. It's easier to collect data where all providers are part of a single system. For example, an early study in Carlisle, England took advantage of the country's nationalized healthcare system to gather data on Parkinson's cases.
"In ours, we have a large HMO, which has about 3 million members, and when they go to see someone we can capture them," Van Den Eeden said. "It's like a little nationalized healthcare system," he said, because the HMO employs its own doctors and has its own facilities. Now the researchers have turned their attention to figuring out why some groups have higher disease rates than others do. "The two major breakdowns, of course, are going to be environment -- and I use that fairly generically -- and genetics," Van Den Eeden said.
Environmental factors include smoking, which may actually reduce the risk of Parkinson's, exposure to some metals used in industry, which may increase the risk, and exposure to pesticides, which is also believed to increase the risk. "Most of our pesticide exposure came from childhood and young adulthood, as opposed to current exposure. So it may be that Hispanics when they were younger used more pesticides than the average non-Hispanic white in our study. We don't know that, but we are looking into it," Van Den Eeden said.
The present study was funded by a grant from the National Institute of Neurologic Disease and Stroke.