title: Cognitive consequences of high Aβ amyloid in mild cognitive impairment and healthy older adults: implications for early detection of Alzheimer's disease.
abstract: BACKGROUND
  It has been proposed that only mild cognitive impairment (MCI) with high Aβ amyloid is indicative of incipient Alzheimer's disease (AD), yet MCI with low Aβ amyloid may reflect other neurodegenerative processes. We aimed to determine the extent to which high Aβ amyloid influenced cognitive function in healthy older adults and adults with MCI.
  
  
  METHODS
  Healthy controls (HC; n = 178) and adults with MCI (n = 56) enrolled in the Australian Imaging, Biomarkers, and Lifestyle study, underwent positron emission tomography neuroimaging for Aβ amyloid and completed an extensive neuropsychological battery, assessing the cognitive domains of verbal and visual episodic memory, executive function, visuoconstruction, attention and processing speed, and language at baseline.
  
  
  RESULTS
  MCI with low Aβ performed worse than MCI with high Aβ on measures of executive function, attention, visuoconstruction and language. No differences were observed between HC high and low Aβ groups. When compared with HC with low Aβ, both MCI high and low Aβ groups performed worse on measures of episodic memory. However, only the MCI low Aβ group performed worse than HC low Aβ on measures of executive function, attention, visuoconstruction, and language.
  
  
  CONCLUSIONS
  When compared with HC with low Aβ amyloid, MCI with high Aβ amyloid present with impairments restricted to episodic memory, and the episodic memory impairments in MCI with low Aβ amyloid were accompanied by impairments in executive function, attention, visuoconstruction, and language, suggesting that MCI with high Aβ amyloid reflects prodromal AD, although further longitudinal data is required to confirm this.
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Yen Ying
authors.initials: YY
authors.lastname: Lim
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Karra
authors.initials: K
authors.lastname: Harrington
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Adrian
authors.initials: A
authors.lastname: Kamer
authors.affiliation: Department of Psychiatry, Yale University School of Medicine.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Pietrzak
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Ashley I
authors.identifier: 0000-0001-8259-9069
authors.initials: AI
authors.lastname: Bush
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: David
authors.initials: D
authors.lastname: Darby
authors.affiliation: Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.affiliation: Department of Nuclear Medicine and Centre for PET, Austin Health.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
authors.affiliation: Department of Psychology and ARC Centre of Excellence in Cognition and its Disorders, Macquarie University.
authors.forename: Greg
authors.initials: G
authors.lastname: Savage
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Cassandra
authors.identifier: 0000-0002-3698-2590
authors.initials: C
authors.lastname: Szoeke
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, St George's Hospital.
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.affiliation: Mental Health Research Institute, The University of Melbourne.
authors.forename: Paul
authors.identifier: 0000-0002-6947-9537
authors.initials: P
authors.lastname: Maruff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001288:Attention; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D003071:Cognition; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D042241:Early Diagnosis; D056344:Executive Function; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D062706:Prodromal Symptoms; D011877:Radionuclide Imaging
chemical_list: D016229:Amyloid beta-Peptides