Neuropathology and Cognitive Impairment in Alzheimer Disease: A Complex but Coherent Relationship

Amyloid plaques and neurofibrillary tangles (NFTs) are the pathological hallmarks of Alzheimer disease (AD), There is controversy regarding the use of current diagnostic criteria for AD and whether amyloid plaques and NFTs contribute to cognitive impairment. Because AD is specific to humans, rigorous and comprehensive clinicopathologic studies are necessary to test and refine hypotheses of AD diagnosis and pathogenesis. Neither the clinical nor the pathological aspects of AD evolve in a linear manner. but the predictable sequence of AD pathology allows for stage-based correlations with cognitive deterioration. We discuss Subsets of patients with clinical dementia who lack amyloid plaques and NFTs and, conversely. whether individuals Without antemortem cognitive impairment call harbor severe AD-type pathological findings at autopsy. There are many medical. technical, and anatomical challenges to clinicopathologic Studies in AD. For example, at least two thirds of persons older than 80 years have non-AD brain diseases that call effect oil cognitive function. We argue that existing data strongly Support the hypothesis that both amyloid plaques and NFTs contribute to cognitive impairment.