Biochemical heterogeneity of Alzheimer's disease

Abstract
Amyloid β protein (Aβ) amyloid deposition is an important early event in the evolution of Alzheimer's disease (AD) pathology. Serial extraction studies of AD brains showed that a large amount of modified Aβ (4, 3.7 and 3 kDa Aβ species) was accumulated as forms with differing solubilities. Immunostaining using specific antibodies to the N and C terminus of Aβ showed that N‐terminally modified Aβ ending at 42A were predominant in senile plaques. Quantitative assay of Aβ in AD brain revealed that Aβ ending at 40 V were correlated with vascular amyloids and that Aβ ending at 42(43) were related with senile plaque amyloids. The site of Aβ deposits may be determined by the heterogeneous length of the C terminus Aβ. The amount of Aβ amyloids may be correlated with N‐terminal modification of Aβ. Thus, heterogeneity of Aβ species is a crucial biochemical factor of AD pathogenesis.