Increased tau accumulation in senile plaques as a hallmark in Alzheimer's disease.

To identify the tau component in senile or kuru plaques, the authors examined brain sections from 12 patients with Alzheimer's disease (AD), 6 with Creutzfeldt-Jakob disease (CJD), and 20 nondemented aged controls using anti-beta protein, anti-buman prion protein, and affinity-purified tau-specific antibody. The tau component was identified both in senile and kuru plaques. In AD, tau-positive senile plaques were found in all cerebral cortices of almost all cases, and the tau-positivity of plaques in cerebral cortices was 5.1 to 27.5%. In CJD, tau-positive senile and kuru plaques were restricted to the hippocampus, and the tau-positivity was 4.3 and 1.2%, respectively. In nondemented aged controls, tau-positive senile plaques also were restricted mostly to the hippocampus, and the tau-positivity was 1.3%. Significant differences in the tau-positivity of senile plaques were found between AD and CJD and nondemented aged controls, and no significant differences were found between CJD and nondemented aged controls. These observations are important because increased tau accumulation in senile plaques can be a hallmark of AD.