title: Changes in plasma amyloid beta in a longitudinal study of aging and Alzheimer's disease.
abstract: BACKGROUND
  A practical biomarker is required to facilitate the preclinical diagnosis of Alzheimer's disease (AD).
  
  
  METHODS
  Plasma amyloid beta (Aβ)1-40, Aβ1-42, Aβn-40, and Aβn-42 peptides were measured at baseline and after 18 months in 771 participants from the Australian Imaging Biomarkers and Lifestyle (AIBL) study of aging. Aβ peptide levels were compared with clinical pathology, neuroimaging and neuropsychological measurements.
  
  
  RESULTS
  Although inflammatory and renal function covariates influenced plasma Aβ levels significantly, a decrease in Aβ1-42/Aβ1-40 was observed in patients with AD, and was also inversely correlated with neocortical amyloid burden. During the 18 months, plasma Aβ1-42 decreased in subjects with mild cognitive impairment (MCI) and in those transitioning from healthy to MCI.
  
  
  CONCLUSIONS
  Our findings are consistent with a number of published plasma Aβ studies and, although the prognostic value of individual measures in any given subject is limited, the diagnostic contribution of plasma Aβ may demonstrate utility when combined with a panel of peripheral biomarkers.
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia. Electronic address: a.rembach@unimelb.edu.au.
authors.forename: Alan
authors.initials: A
authors.lastname: Rembach
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Noel G
authors.initials: NG
authors.lastname: Faux
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Watt
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Kelly K
authors.initials: KK
authors.lastname: Pertile
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Rumble
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Brett O
authors.initials: BO
authors.lastname: Trounson
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Fowler
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Blaine R
authors.initials: BR
authors.lastname: Roberts
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Keyla A
authors.initials: KA
authors.lastname: Perez
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Qiao-Xin
authors.initials: QX
authors.lastname: Li
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia; Centre of Excellence for Alzheimer's Disease Research & Care, School of Medical Sciences, Edith Cowan University, Joondalup. Western Australia, Australia.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Laws
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia; Centre of Excellence for Alzheimer's Disease Research & Care, School of Medical Sciences, Edith Cowan University, Joondalup. Western Australia, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Taddei
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia; Centre of Excellence for Alzheimer's Disease Research & Care, School of Medical Sciences, Edith Cowan University, Joondalup. Western Australia, Australia.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Rainey-Smith
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Robertson
authors.affiliation: Department of Diagnostic Development, Innogenetics NV, Ghent, Belgium.
authors.forename: Manu
authors.initials: M
authors.lastname: Vandijck
authors.affiliation: Department of Diagnostic Development, Innogenetics NV, Ghent, Belgium; Biomarkable, Gent, Belgium.
authors.forename: Hugo
authors.initials: H
authors.lastname: Vanderstichele
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Barnham
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia; Department of Psychiatry, St George's Hospital, University of Melbourne, Victoria, Australia; National Ageing Research Institute, Parkville, Victoria, Australia.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
authors.affiliation: Department of Psychiatry, St George's Hospital, University of Melbourne, Victoria, Australia; National Ageing Research Institute, Parkville, Victoria, Australia.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Szoeke
authors.affiliation: CSIRO Molecular and Health Technologies, Parkville, Victoria, Australia.
authors.forename: Lance
authors.initials: L
authors.lastname: Macaulay
authors.affiliation: Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia; Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia.
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.affiliation: National Ageing Research Institute, Parkville, Victoria, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia; Centre of Excellence for Alzheimer's Disease Research & Care, School of Medical Sciences, Edith Cowan University, Joondalup. Western Australia, Australia.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Ashley I
authors.initials: AI
authors.lastname: Bush
authors.affiliation: The Mental Health Research Institute, The University of Melbourne, Victoria, Australia.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D000544:Alzheimer Disease / Q000097:blood* / Q000000981:diagnostic imaging / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000097:blood*; D053327:Apolipoprotein E4 / Q000235:genetics; D016009:Chi-Square Distribution; D060825:Cognitive Dysfunction / Q000097:blood / Q000000981:diagnostic imaging; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000097:blood*; D049268:Positron-Emission Tomography
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)
keywords: Alzheimer's disease; Amyloid-β; Biomarkers; Diagnosis; Pittsburgh compound B; Positron emission tomography