Jacksonville, Fla. – Parkinson’s disease affects more than 800,000 Caucasian Americans; however, the extent that it affects minority populations is unknown. The frequency, genetic makeup and environmental risk of Parkinson’s disease in Native Americans are poorly understood.
Jill Marjama-Lyons, M.D., Parkinson’s program director at Shands Jacksonville and a University of Florida assistant professor of neurology, identified a cluster of Parkinson’s disease in the Navajo of New Mexico and clinically evaluated 50 patients in order to determine some of these factors. “The Navajo are a unique population in that they have bred almost exclusively within their tribe,” she says. “They have remained in the same geographic area resulting in a genetically and environmentally isolated people.”
Marjama-Lyons performed a detailed history-family, occupational and environmental-and a neurological examination. Patients were also assessed for motor symptoms of Parkinson’s disease (such as frequency of falling) so improvement could be measured. Additionally, patients were given education materials and treatment during the initial examination and again during a six-month follow-up exam.
Results of the study showed that all of the evaluated patients shared several common factors: all patients were born, raised and currently live in the rural four corners of the southwestern United States; all drank from well water or natural water sources; most were involved with dipping of sheep into containers of insecticides during childhood; and many shared common occupations such as sheepherding, rug weaving, jewelry making, farming, coal and uranium mining or working at an agricultural plant.
Some of the other findings revealed that 27 percent of the evaluated patients had a family history of Parkinson’s disease and the average age of onset of the disease was 53 years of age. At the initial exam, it was determined that 90 percent of the patients had received poor medical treatment but significant improvement was made by the six-month follow-up exam. Improvements were increased independence due to better speed of movement, less shaking and less rigid muscles in 77 percent of the patients. In addition, 80 percent had a reduction in their frequency of falling.
Marjama-Lyons believes that the high rate of a positive family history for Parkinson’s disease makes it likely that an inherited form of Parkinson’s exists in the Navajo. She also believes that even though no one environmental agent has been proven to cause this disease in the Navajo, several environmental factors may prove to be linked to Parkinson’s disease in this population. Marjama-Lyons notes it has long been observed and reported that Parkinson’s disease has a higher incidence in non-Native Americans who live in rural areas, drink well water and have been exposed to insecticides and pesticides.
The Shands Parkinson’s program director hopes to return to New Mexico for further study. “I believe there are more than 300 or 400 Navajo persons with Parkinson’s and I hope to gain permission from the tribal board to study possible environmental and genetic factors that might be the cause of the disease.”