Risk factors for Parkinson's disease are difficult to identify because the cause of the disease is unknown. Advancing age is the only known risk factor for typical Parkinson's disease (not including early-onset Parkinson's). Most instances of Parkinson's disease occur after age 50, although the illness does occur in people between the ages of 30 and 50, or in rare cases at a younger age.

A very small number of people with Parkinson's have a close relative who also has the disease, but it does not appear that a family history of typical Parkinson's disease significantly increases your risk of developing the disease. Having a family history of the disease is a more significant risk factor in cases of early-onset Parkinson's disease, but this form of the disease is not common.

Some research suggests that long-term exposure to certain environmental factors such as pesticides, chemicals, or well water may increase a person's risk of developing Parkinson's disease, but this has not been proven.

There are many other causes of parkinsonism, which is a group of symptoms that includes tremor, muscle stiffness, slow movement, and unsteady walking. Parkinsonism mimics Parkinson's disease, but in fact is not Parkinson's disease.