The burden of Parkinson's disease: a worldwide perspective

Over history, diseases have appeared and disappeared, or have increased or decreased in frequency. These epidemiological trends have occurred more dramatically for infectious diseases (eg, the eradication of small pox), but have also occurred for chronic diseases (eg, reduction of vitamin deficiencies and cardiovascular disease).1 Over the past three or four decades, changing trends in the epidemiology of neurological diseases have been reported. In some high-income countries (primarily in North America and western Europe), the risk of stroke and dementia has declined, but the risk of Parkinson's disease and parkinsonism, amyotrophic lateral sclerosis, and late-onset multiple sclerosis has increased.