Fibrillar amyloid β protein (Aβ) deposition is increased in the brains of patients with Alzheimer's disease (AD), and is manifested as senile plaques (SPs) and congophilic angiopathy (CA). Aβ40 and Aβ42(43), two chief species of Aβ, are documented in SPs and CA, as well as in cerebrospinal fluid (CSF) and cell culture media. Aβ42(43) is the major component of diffuse plaques, the earliest form of SPs. Thus, we hypothesized that determination of the amount of Aβ42(43) in CSF or plasma might provide a diagnostic laboratory test for AD. We measured amounts of different Aβ species in plasma from 28 patients with sporadic probable AD, 40 age-matched neurologic patients without dementia and 25 age-matched normal controls using enzyme-linked immunosorbent assays (ELISAs). Plasma concentrations of Aβ1-40 and Aβ1-42(43) did not significantly differ among these groups. These findings suggest the unlikelihood that plasma Aβ assays would be useful as a diagnostic tool for AD.
ASJC Scopus subject areas