Parkinson disease (PD) is a progressive neurodegenerative disorder characterized by motor symptoms such as bradykinesia, tremor, and gait and postural abnormalities as well as neuropsychiatric and other nonmotor symptoms. It is more common in older adults and increases in prevalence with age, although it can also affect younger individuals. Worldwide, approximately 7.5 million people are estimated to be living with PD, and by 2040 this number is expected to double over the next 2 decades.