DIAGNOSTIC-CRITERIA FOR THE NEUROPATHOLOGIC ASSESSMENT OF ALZHEIMERS-DISEASE

The provisional criteria proposed in 1985 by Khachaturian et al. empha sized numbers of plaques and neglected tangles, as did CERAD (Consorti um to Establish a Registry for Alzheimer's Disease). The decision to s et an arbitrary number of plaques as ''pathologic'' assumed that some neuritic plaques are a normal phenomenon in the aging brain. Neuritic plaques and neurofibrillary tangles are age-related lesions, but they are pathologic (i.e., lesions) no matter how many there are. In a clin ically demented patient without vascular or other neurodegenerative le sions, a clinico-pathologic diagnosis of AD (a clinico-pathologic enti ty) can be made with a high level of confidence by demonstrating, and without counting, plaques and tangles. The vast majority of AD cases a re straightforward, and diagnostic lesions can be appreciated with a s imple silver stain. If patients' histories are unknown or uncertain, t he clinical significance of the observed plaques and tangles must rema in debatable. This is the essence of the consensus statement with whic h I wholeheartedly agree. In such cases without a dementia history, on e can offer a neuropathologic diagnosis of Senile or Pre-senile Cerebr al Disease (not ''dementia'') of the Alzheimer type. Precise clinico-p athologic correlations and some quantitative measures are needed for e lucidating the pathogenesis of AD and for establishing a primary demen ting diagnosis when AD is mixed with other dementing diseases. These c orrelations must be based on periodic and fairly extensive neuropsycho logical testing followed shortly thereafter by a detailed postmortem n europathologic evaluation. (C) 1997 Elsevier Science Inc.