title: Plasma amyloid-beta as a biomarker in Alzheimer's disease: the AIBL study of aging.
abstract: Amyloid-beta (Abeta) plays a central role in the pathogenesis of Alzheimer's disease (AD) and has been postulated as a potential biomarker for AD. However, there is a lack of consensus as to its suitability as an AD biomarker. The objective of this study was to determine the significance of plasma Abeta as an AD biomarker and its relationship with Abeta load and to determine the effect of different assay methods on the interpretation of Abeta levels. Plasma Abeta1-40, Abeta1-42, and N-terminal cleaved fragments were measured using both a commercial multiplex assay and a well-documented ELISA in 1032 individuals drawn from the well-characterized Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging. Further, Abeta levels were compared to Abeta load derived from positron-emission tomography (PET) with the Pittsburgh compound B (PiB). Lower Abeta1-42 and Abeta1-42/1-40 ratio were observed in patients with AD and inversely correlated with PiB-PET derived Abeta load. However, assay methodology significantly impacted the interpretation of data. The cross-sectional analysis of plasma Abeta isoforms suggests that they may not be sufficient per se to diagnose AD. The value of their measurement in prognosis and monitoring of AD interventions needs further study, in addition to future longitudinal comparisons together with other predictors, which will determine whether plasma Abeta has diagnostic value in a panel of biomarkers.
authors.affiliation: Centre of Excellence for Alzheimer's Disease Research & Care, School of Exercise Biomedical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.
authors.forename: James K
authors.initials: JK
authors.lastname: Lui
authors.forename: Simon M
authors.initials: SM
authors.lastname: Laws
authors.forename: Qiao-Xin
authors.initials: QX
authors.lastname: Li
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.forename: Belinda
authors.initials: B
authors.lastname: Brown
authors.forename: Ashley I
authors.initials: AI
authors.lastname: Bush
authors.forename: Karl
authors.initials: K
authors.lastname: De Ruyck
authors.forename: Jasmin
authors.initials: J
authors.lastname: Dromey
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
authors.forename: Noel G
authors.initials: NG
authors.lastname: Faux
authors.forename: Jonathan
authors.initials: J
authors.lastname: Foster
authors.forename: Christopher
authors.initials: C
authors.lastname: Fowler
authors.forename: Veer
authors.initials: V
authors.lastname: Gupta
authors.forename: Peter
authors.initials: P
authors.lastname: Hudson
authors.forename: Katrina
authors.initials: K
authors.lastname: Laughton
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.forename: Kelly
authors.initials: K
authors.lastname: Pertile
authors.forename: Alan
authors.initials: A
authors.lastname: Rembach
authors.forename: Mira
authors.initials: M
authors.lastname: Rimajova
authors.forename: Mark
authors.initials: M
authors.lastname: Rodrigues
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
authors.forename: Rebecca
authors.initials: R
authors.lastname: Rumble
authors.forename: Cassandra
authors.initials: C
authors.lastname: Szoeke
authors.forename: Kevin
authors.initials: K
authors.lastname: Taddei
authors.forename: Tania
authors.initials: T
authors.lastname: Taddei
authors.forename: Brett
authors.initials: B
authors.lastname: Trounson
authors.forename: Vanessa
authors.initials: V
authors.lastname: Ward
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.lastname: AIBL Research Group
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D000544:Alzheimer Disease / Q000097:blood* / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000097:blood*; D001057:Apolipoproteins E / Q000378:metabolism; D001315:Australia; D015415:Biomarkers; D001921:Brain / Q000473:pathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D009483:Neuropsychological Tests; D018570:Risk Assessment; D012959:Socioeconomic Factors
chemical_list: D016229:Amyloid beta-Peptides; D001057:Apolipoproteins E; D015415:Biomarkers