Parkinson Disease: Epidemiology, Pathology, and Clinical Diagnosis

Abstract

Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease. PD predominantly affects elderly people, and most countries are now facing a marked demographic change, with a progressively larger proportion of the population reaching old age. Thus, PD is expected to cause an increasing social and economic burden on society in the near future. The causes of PD are still mostly unknown. There has been a substantial progress in our understanding of the genetic basis of PD in the past 15 years; however, these mutations explain only a small fraction of all PD cases and other non-genetic factors may play a role. This review covers the epidemiology, pathology, and clinical diagnosis of PD. Figures show age-specific incidence of PD, age-specific prevalence of PD, PD risks for exposures reported in high-quality studies, PD and atypical parkinsonism clinical features, and neuroimaging alterations in PD and atypical parkinsonism. Tables list factors associated with increased or decreased risk of PD, Braak staging scheme of α-synuclein pathology in PD, United Kingdom Parkinson’s Disease Society Brain Bank clinical diagnostic for PD, National Institute of Neurological Disorders and Stroke diagnostic criteria for PD, differential diagnosis of parkinsonian syndromes, and “atypical” atypical parkinsonism.