The diagnosis of Alzheimer’s disease: assessment and criteria

Abstract Alzheimer’s disease (AD) is the most prevalent form of dementia: it accounts for 70% of cases of progressive cognitive impairment in aged individuals, age being the single most important risk factor. The disease is linked with ageing, but it is not due to ageing, as exemplified by early onset cases. AD has characteristic clinical features, usually including various combinations of memory impairment, executive deficits, impaired instrumental functions, and behavioural/neuropsychiatric disturbances that may interfere with functioning of activity of daily living. Detailed neuropsychological testing with standardized assessment is required for quantifying the deficits of AD and may aid distinguishing AD from other degenerative dementias. The clinical diagnosis of AD has traditionally required exclusion of alternative explanations for cognitive decline using blood testing and brain neuroimaging techniques. A new conceptual framework based on pathophysiological biomarkers has been recently proposed that includes the prodromal (predementia) stage in the diagnostic algorithm.