Parkinson Disease is a comprehensive introduction to the biology and clinical features of Parkinson disease (PD). This book is aimed at clinicians in training, general neurologists seeking a useful guide to PD, and scientists seeking an overview of clinical aspects of PD. Topics covered include nosology of PD, PD epidemiology, pathology and pathophysiology of PD, and theories of PD pathogenesis. Clinical features, including the many non-motor features, natural history of disease progression, clinical pharmacology, and management of PD receive coverage. Important themes are heterogeneity of PD, the multi-focal nature of PD pathology, the diversity of clinical features, dopaminergic signaling and the impacts of dopaminergic deficiency, the importance of non-motor features, limitations of existing treatment modalities, and the necessity of approaching PD as a multi-system disorder. The description and discussion of the many aspects of Parkinson disease (PD) is dogged by the fact that PD is an ambiguous concept. This book intends to be a useful overview, bridging the gap between general textbooks and specific topical reviews.