The exact cause of Parkinson's disease is unknown. Scientists think that Parkinson's is probably due to a combination of genetic and environmental factors.
Specific genetic factors appear to play a strong role in early-onset Parkinson's disease, an uncommon form of the disease. Recent research suggests that multiple genetic factors may also be involved in some cases of late-onset Parkinson's disease.
Environmental factors alone are probably not a cause of Parkinson's disease, but they may trigger the condition in people who are genetically susceptible.
Some evidence implicates pesticides and herbicides as possible factors in some cases of Parkinson's disease. A higher incidence of parkinsonism has long been observed in people who live in rural areas, particularly those who drink private well water or are agricultural workers.
Review Date: 06/18/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.