title: Plasma apolipoprotein J as a potential biomarker for Alzheimer's disease: Australian Imaging, Biomarkers and Lifestyle study of aging.
abstract: BACKGROUND
  For early detection of Alzheimer's disease (AD), the field needs biomarkers that can be used to detect disease status with high sensitivity and specificity. Apolipoprotein J (ApoJ, also known as clusterin) has long been associated with AD pathogenesis through various pathways. The aim of this study was to investigate the potential of plasma apoJ as a blood biomarker for AD.
  
  
  METHODS
  Using the Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging, the present study assayed plasma apoJ levels over baseline and 18 months in 833 individuals. Plasma ApoJ levels were analyzed with respect to clinical classification, age, gender, apolipoprotein E (APOE) ε4 allele status, mini-mental state examination score, plasma amyloid beta (Aβ), neocortical Aβ burden (as measured by Pittsburgh compound B-positron emission tomography), and total adjusted hippocampus volume.
  
  
  RESULTS
  ApoJ was significantly higher in both mild cognitive impairment (MCI) and AD groups as compared with healthy controls (HC; P < .0001). ApoJ significantly correlated with both "standardized uptake value ratio" (SUVR) and hippocampus volume and weakly correlated with the plasma Aβ1-42/Aβ1-40 ratio. Plasma apoJ predicted both MCI and AD from HC with greater than 80% accuracy for AD and greater than 75% accuracy for MCI at both baseline and 18-month time points.
  
  
  CONCLUSIONS
  Mean apoJ levels were significantly higher in both MCI and AD groups. ApoJ was able to differentiate between HC with high SUVR and HC with low SUVR via APOE ε4 allele status, indicating that it may be included in a biomarker panel to identify AD before the onset of clinical symptoms.
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia; Cooperative Research Centre for Mental Health, Melbourne, Australia.
authors.forename: Veer Bala
authors.initials: VB
authors.lastname: Gupta
authors.affiliation: CSIRO Health and Biosecurity, Brisbane, Australia.
authors.forename: James D
authors.initials: JD
authors.lastname: Doecke
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia; Cooperative Research Centre for Mental Health, Melbourne, Australia.
authors.forename: Eugene
authors.initials: E
authors.lastname: Hone
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia; Cooperative Research Centre for Mental Health, Melbourne, Australia.
authors.forename: Steve
authors.initials: S
authors.lastname: Pedrini
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia; Cooperative Research Centre for Mental Health, Melbourne, Australia.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Laws
authors.affiliation: Unit of Clinical and Translational Neuroscience Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
authors.forename: Madhav
authors.initials: M
authors.lastname: Thambisetty
authors.affiliation: Cooperative Research Centre for Mental Health, Melbourne, Australia; Oxidation Biology Unit, The Florey Institute, The University of Melbourne, Melbourne, Australia.
authors.forename: Ashley I
authors.initials: AI
authors.lastname: Bush
authors.affiliation: Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Australia.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
authors.affiliation: Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Australia.
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.affiliation: National Ageing Research Institute, Parkville, Australia; Academic Unit for Psychiatry of Old age, St. George's Hospital, The University of Melbourne, Melbourne, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.affiliation: Oxidation Biology Unit, The Florey Institute, The University of Melbourne, Melbourne, Australia.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.affiliation: CSIRO Food and Nutrition Flagship, Parkville, Australia.
authors.forename: Stuart Lance
authors.initials: SL
authors.lastname: Macaulay
authors.affiliation: Oxidation Biology Unit, The Florey Institute, The University of Melbourne, Melbourne, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Rembach
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Rainey-Smith
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia; Cooperative Research Centre for Mental Health, Melbourne, Australia; School of Psychiatry and Clinical Neurosciences, University of Western Australia, Perth, Australia.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
keywords: Apolipoprotein J; Biomarkers; Brain amyloid beta; Hippocampus volume; Plasma