Plasma amyloid-β oligomers level is a biomarker for Alzheimer's disease diagnosis

Abstract

Amyloid beta (Abeta), especially Abeta oligomers, is important in Alzheimer's disease (AD) pathogenesis. We studied plasma Abeta(40), Abeta(42), and Abeta oligomers levels in 44 AD patients and 22 non-demented controls. Cognitive functions were assessed by Chinese version of mini-mental state examination (MMSE), Abbreviated Metal Test (AMT), Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-cog). Plasma Abeta monomers and oligomers levels were measured by ELISA. We found that the median plasma Abeta(40) and Abeta(42) levels were similar between AD and controls, and without significant correlation with cognition. Plasma Abeta oligomers level was higher in AD than controls (642.54ng/ml [range 103.33-2676.93] versus 444.18ng/ml [range 150.19-1311.18], p=0.047), and negatively correlated with cognition. In multivariate logistic regression analysis, the highest tertile of Abeta oligomers levels showed an increased risk of AD than the combined group of middle and lowest tertiles (OR=8.85, p=0.013), after adjustment of gender, age and APOE4 genotype. Increased plasma Abeta oligomers level was associated with decreased MMSE and AMT scores (p=0.037, p=0.043, respectively) and increased ADAS-cog score (p=0.036), suggesting negative correlation with cognitive function. We concluded that plasma Abeta oligomers level is an useful biomarker for AD diagnosis.