The diagnosis of Alzheimer's disease

Dementia constitutes a growing public health crisis. Early and accurate diagnosis of dementia is essential in order to provide patient and family counseling and appropriate treatment, including with specific antidementia drugs as they become increasingly available. Age-related cognitive decline, as compared with dementia, does not seriously interfere with usual activities. The optimal approach to early detection of dementia is clinical examination that incorporates information from a reliable collateral source about how the patient's cognitive abilities have declined relative to past performance. Alzheimer's disease (AD), the most common cause of dementia, can be diagnosed clinically with high accuracy (=85%) using standardized criteria. Even incipient AD can be detected with clinical methods alone. Although the typical picture of AD is characterized by gradual onset and progression of memory and other cognitive deficits, in other respects the disease is marked by heterogeneity. Early and late-onset AD represent the most easily recognized subtypes. Research continues towards characterizing a biologic marker but, as of yet, no candidate marker surpasses the high diagnostic accuracy of clinical assessments alone. At present, the diagnosis of AD rests primarily in the hands of the clinician.