Background
Parkinson’s disease (PD) is the most common serious movement disorder in the world, affecting about 1% of adults older than 55 years. It represents the most common example of a family of neurodegenerative disorders characterized by variable degrees of “parkinsonism” which is defined as a paucity and slowness of movement (bradykinesia), tremor at rest, rigidity, shuffling gait, and flexed posture. Parkinsonism results from a reduction of dopaminergic transmission within the basal ganglia.