Parkinson’s disease (PD) is a progressive and disabling neurologic disorder. The disease is the most prevalent type of parkinsonism, a clinical syndrome caused by lesions in the basal ganglia, predominantly in the substantia nigra, which produces deficits in motor behavior. PD occurs when certain neurons in the substantia nigra die or become impaired. See Figure 1. Normally, these cells produce the chemical dopamine, which allows for smooth, coordinated function of the body’s muscles and movement.1-3 The symptoms of PD appear when approximately 80% of the dopamineproducing cells are damaged.3 After Alzheimer’s disease, PD is the second most common neurodegenerative condition affecting an estimated 3% of Americans aged 65 and older.4,5 PD, which makes up approximately 80% of cases of parkinsonism, affects 4 million people worldwide.1,2 The brain disorder is more common in men, with a male-to-female ratio of 3:2.2 As prevalence and incidence of PD increase with age, the number of individuals afflicted is expected to rise considerably.