title: The association of Aβ amyloid and composite cognitive measures in healthy older adults and MCI.
abstract: BACKGROUND
  To date evidence of the relationship between cognition and Aβ amyloid during the early stages of Alzheimer's Disease (AD) has been inconsistent. This study aimed to describe the nature and magnitude of the relationship between Aβ amyloid and cognitive performance of individuals without dementia.
  
  
  METHODS
  Composite cognitive measures were developed from the Australian Imaging Biomarkers and Lifestyle study neuropsychological test battery using data from 768 healthy older adults and 133 adults with mild cognitive impairment (MCI). A subgroup of this sample (174 healthy, 53 MCI) underwent neuroimaging for Aβ amyloid.
  
  
  RESULTS
  Within the MCI group individuals with high Aβ amyloid showed selective impairment for memory compared with those with low Aβ amyloid; however, this difference was not evident in the healthy group.
  
  
  CONCLUSIONS
  The current findings provide further evidence of the relationship between Aβ amyloid and cognition, with memory impairment being the primary symptom of the underlying disease during the prodromal phases of AD.
authors.affiliation: Mental Health Research Institute, The University of Melbourne, Parkville, Victoria, Australia. karra.harrington@florey.edu.au
authors.forename: Karra D
authors.initials: KD
authors.lastname: Harrington
authors.forename: Yen Ying
authors.initials: YY
authors.lastname: Lim
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
authors.forename: Carly
authors.initials: C
authors.lastname: Copolov
authors.forename: David
authors.initials: D
authors.lastname: Darby
authors.forename: Michael
authors.initials: M
authors.lastname: Weinborn
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.forename: Greg
authors.initials: G
authors.lastname: Savage
authors.forename: Cassandra
authors.initials: C
authors.lastname: Szoeke
authors.forename: Christopher
authors.initials: C
authors.lastname: Rowe
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.forename: Paul
authors.initials: P
authors.lastname: Maruff
mesh_terms: D000368:Aged; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001921:Brain / Q000473:pathology*; D003071:Cognition; D060825:Cognitive Dysfunction / Q000473:pathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D059906:Neuroimaging; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography
chemical_list: D016229:Amyloid beta-Peptides