Neuropathological Diagnosis of Sen1ile Dementia of the Alzheimer Type (SDAT): Proposal of Diagnostic Criteria and Report of the Japanese Research Meeting on Neuropathological Diagnosis of SDAT

Tentative neuropathological diagnostic criteria of senile dementia of the Alzheimer type (SDAT) are proposed in this report of the activities of the Japanese Research Meeting on Neuropathological Diagnosis of SDAT. The criteria include: 1) The exclusion of other diseases that cause dementia; 2) Senile plaques (SPs) and Alzheimer's neurofibrillary tangles (NFTs) above the upper normal limits in more than one cerebral gyrus, and 3) Laminar degeneration in the entorhinal cortex. Our criteria are considered to be better suited for confirmation of clinical SDAT than the previous ones, since more than 90% of the cases that satisfied the proposed criteria were clinically diagnosed as having SDAT. On the other hand, the application of our criteria to 1,000 consequent autopsies showed that not all cases with clinically diagnosed SDAT had pathologically stereotypical features of this disease. Such cases include: 1) those that only had SPs in the cerebral cortex, but no significant numbers of NFTs and no apparent cerebral atrophy; 2) those in which numerous NFTs were concentrated in the hippocampus, and 3) those with marked fibrillary gliosis in the temporal white matter and unusual clinical symptoms. These results could reflect the pathological heterogeneity of SDAT and the difference between Alzheimer's disease and SDAT.