A Prospective Study of Cognitive Function and Onset of Dementia in Cognitively Healthy Elders

Abstract

DETECTING Alzheimer disease in its early stages challenges researchers and clinicians alike. To warrant a diagnosis of dementia of the Alzheimer type (DAT), cognitive impairment must interfere with previous levels of functioning in usual activities.^1,2 This determination, which often is difficult when dementia is very mild, generally relies on reports of subtle cognitive and functional decline from either the individual or a knowledgeable collateral source. Performance on a standardized battery of tests of cognitive function may not be helpful in very mild stages of DAT because cognitive abilities vary among healthy individuals, and decline may not always be reflected by scores in impaired ranges. An alternative strategy to the 1-time administration of such a battery is longitudinal assessment.³