ABSTRACT
In 1817, the —rst published description of Parkinson’s disease (PD) by James Parkinson (1817) described the “shaking palsy” in which patients suffered from a gradual onset of involuntary tremor at rest, slowness of movement, rigidity, and postural instability. These characteristic motor de—cits of PD remain the cardinal features used for clinical diagnosis today, but it also is now widely recognized that there are other motor symptoms, including changes in gait, micrographia, and restless legs (Marsden 1994; Jankovic 2008). PD is still commonly considered a movement disorder, but we know that it also gives rise to nonmotor cognitive and psychological symptoms, including impaired memory (Owen et al. 1992), altered learning (Smith and McDowall 2006), sleep disruptions (Braak et al. 2003), hallucinations, and changes in reaction time and perception. Currently, the disease affects 1.3% to 1.5% of Europeans (Von Campenhausen et al. 2005), with symptoms typically emerging in the sixth and seventh decades of life (A. Hughes et al. 1992).
