Parkinson’s disease (PD) is a neurodegenerative disorder that primarily affects neurons that produce dopamine in a region of the brain called the substantia nigra. This region of the brain is responsible for movement and coordination. The degenerative movement disorder known as Parkinson’s disease is a disorder of the nervous system that can progress over time. It comes on gradually, and its first symptom may be a tremor that is so slight that it is only noticeable in one hand. However, although tremor is the symptom of Parkinson’s disease that is most well-known to the general public, the disorder also frequently causes stiffness or a slowing of movement.