In recent years, considerable advances have been made in our knowledge and understanding of Parkinson's disease (PD). In particular, there has been an explosion of information regarding genetic contributions to the etiology of PD and an increased awareness of the incidence and importance of the non-motor features of the disease. Theories regarding the pathogenesis and pathophysiology of PD have also been refined, and new treatment modalities and advances have been implemented. Reflecting these changes, this second edition features new chapters devoted to genetic aspects of PD, nonmotor features of the disease, as well as aspects of the pathophysiology, pathogenesis, and treatment of PD.