Assessment of CSF Aβ42 as an aid to discriminating Alzheimer's disease from other dementias and mild cognitive impairment: A meta-analysis of 50 studies

Mild Alzheimer's disease (AD) is usually difficult to differentiate from other dementias or mild cognitive impairment (MCI). The aim of our study is to evaluate the clinical importance of cerebrospinal fluid (CSF) beta-amyloid 42 (A beta(42)) in MCI, AD and other dementias, more specifically: frontotemporal dementia (FTD), dementia with Lewy bodies (DLB), Parkinson's disease (PD) with dementia (POD) and vascular dementia (VaD). Fifty eligible articles were identified by search of databases including PubMed, EMBASE, Elsevier, Springer Link and the Cochrane Library, from January 1990 to May 2014. The random effects model was used to calculate the standardized mean difference (SMD) with corresponding 95% CI by STATA 9.0 software. The subgroup analyses were made on the method (ELISA, xMAP). We found that CSF A beta(42) concentrations were significantly lower in AD compared to MCI (SMD: -0.68, 95% CI: [-0.80, -0.56], z = 11.34, P < 0.001), FTD (SMD: -1.09, 95% CI: [-1.41, -0.76], z = 6.62, P < 0.001), PDD (SMD: -0.75, 95% CI: [-1.39, -0.10], z = 2.27, P = 0.023), VaD (SMD: -0.95, 95% CI: [-130, -0.61], z = 5.43, P < 0.001). In addition, compared to DLB, A beta(42) concentrations are moderately lower in AD (SMD: -0.27, 95% CI: [-0.51, -0.03], z = 2.20, P = 0.028). Results from this meta-analysis hinted that CSF A beta(42) is a good biomarker for discriminating Alzheimer's disease from other dementias and MCI. (C) 2014 Elsevier B.V. All rights reserved.