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Pathological diagnosis of Alzheimer-type dementia for old-old and oldest-old patients.

The pathological diagnosis of Alzheimer-type dementia (ATD) is reviewed. The problems with the quantitative diagnosis are three-fold: the number of the senile plaques (SP) is not always related to the presence or the absence of dementia; recent research indicates that the SP and the neurofibrillary tangles (NFT) could represent a different level in the pathogenesis of ATD, and finally it has not been seriously discussed whether ATD is the final stage of physiological aging or if ATD is a definitive disease. For these reasons, new diagnostic criteria are proposed in order to differentiate ATD from physiological aging. The new criteria are suitable even in the old-old and oldest-old patients. It is stressed that ATD is heterogeneous in the pathogenetic aspect, consisting of Alzheimer's disease with onset before the age of 70 years (the neocortical type of ATD) and senile dementia of the Alzheimer type (the limbic type of ATD) with the onset after the age of 70. Even in cases with the latter type, there are several atypical ATD and non-ATD forms. "Primary senile dementia' is proposed as a comprehensive term to include various types of senile dementia of unknown etiology.