Plasma amyloid levels within the Alzheimer's process and correlations with central biomarkers

Introduction: Diagnostic relevance of plasma amyloid (beta(A beta) for Alzheimer's disease (AD) process yields conflicting results. The objective of the study was to assess plasma levels of A beta(42) and A beta(40) in amnestic mild cognitive impairment (MCI), nonamnestic MCI, and AD patients and to investigate relationships between peripheral and central biomarkers. Methods: One thousand forty participants (417 amnestic MCI, 122 nonamnestic MCI, and 501 AD) from the Biomarker of AmyLoId pepTide and AlZheimer's diseAse Risk multicenter prospective study with cognition, plasma, cerebrospinal fluid (CSF), and magnetic resonance imaging assessments were included. Results: Plasma A beta(1-42) and A beta(1-40) were lower in AD (36.9 [11.7] and 263 [80] pg/mL) than in amnestic MCI (38.2 [11.9] and 269 [68] pg/mL) than in nonamnestic MCI (39.7 [10.5] and 272 [52] pg/mL), respectively (P =.01 for overall difference between groups for A beta(1-42) and P =.04 for A beta(1-40)). Globally, plasma A beta(1-42) correlated with age, Mini Mental State Examination, and APOE epsilon 4 allele. Plasma A beta(1-42) correlated with all CSF biomarkers in MCI but only with CSF A beta(42) in AD. Discussion: Plasma AO was associated with cognitive status and CSF biomarkers, suggesting the interest of plasma amyloid biomarkers for diagnosis purpose. (C) 2018 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association. This is an open access article under the CC BY-NC-ND license.