The evolving classification of dementia: placing the DSM-V in a meaningful historical and cultural context and pondering the future of "Alzheimer's".

Alzheimer's disease is a 100-year-old concept. As a diagnostic label, it has evolved over the 20th and 21st centuries from a rare diagnosis in younger patients to a worldwide epidemic common in the elderly, said to affect over 35 million people worldwide. In this opinion piece, we use a constructivist approach to review the early history of the terms "Alzheimer's disease" and related concepts such as dementia, as well as the more recent nosological changes that have occurred in the four major editions of the Diagnostic and Statistical Manual since 1952. A critical engagement of the history of Alzheimer's disease and dementia, specifically the evolution of those concepts in the DSM over the past 100 years, raises a number of questions about how those labels and emergent diagnoses, such as Neurocognitive Disorders and Mild Cognitive Impairment, might continue to evolve in the DSM-V, due for release in 2013.