For most people, the exact cause behind Parkinson’s disease is uncertain. It is believed that a combination of factors cause the disease. Those factors may include genetic and environmental triggers. There is much work still to be done in researching what causes Parkinson’s disease.
Parkinson’s disease is rarely inherited, although people with a family history have a higher risk of being diagnosed with it compared to those who don’t. Those with a parent or sibling affected have a 3% risk, while the general population’s risk is only 1.5%. In addition to hereditary factors, mutations in some genes appear to increase a person’s lifetime risk of developing Parkinson’s. Researchers think many of the genetic markers for the disease have not been discovered yet.
Environmental causes include traumatic brain injury, and exposure to harmful materials. A head injury involving loss of consciousness or amnesia is shown to carry an increased risk of developing Parkinson’s, years later.
Exposure to pesticides and other toxic substances may represent another environmental trigger. Certain occupations - such as welding - have a higher incidence of the disease. Some geographic areas also seem to have a higher number of people develop Parkinson’s, but it’s unknown whether that is due to environmental or genetic factors.
When it comes to the numbers, aging is clearly a factor. Parkinson’s disease typically develops in middle age or later. Risk increases with age, and men are one and a half times more likely to develop it than women. Nearly 1 million people in the United States have been diagnosed, and more than 6 million people worldwide are living with Parkinson’s. It is estimated that 60,000 people are diagnosed in the U.S. each year.