AMYLOID-BETA PROTEIN DEPOSITION IN NORMAL AGING HAS THE SAME CHARACTERISTICS AS THAT IN ALZHEIMERS-DISEASE - PREDOMINANCE OF A-BETA-42(43) AND ASSOCIATION OF A-BETA-40 WITH CORED PLAQUES

Two distinct species of amyloid beta protein (A beta) with different C -termini, A beta 42(43) and A beta 40, are deposited in senile plaques (SP) of Alzheimer's disease (AD), with the former being far predomina nt. To investigate whether A beta 42(43) also predominates over A beta 40 in normal aging, we examined by immunocytochemistry the C-termini of A beta in SP in the brains of non-demented aged individuals and com pared the results with those in AD. Virtually all SP were A beta 42(43 )-positive; of these 12% in non-demented aged individuals and 25% in A D patients (mean of three areas examined) were also A beta 40-positive In both the AD and non-demented groups, 2/3 of the A beta 40-positive SP were typical cored SP. These results indicate that A beta 42(43) i s the predominant species deposited in SP in normal aging, and there i s no qualitative difference in terms of the C-terminus of A beta in th e parenchymal amyloid deposition between normal aging and AD.