title: Rates of diagnostic transition and cognitive change at 18-month follow-up among 1,112 participants in the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing (AIBL).
abstract: BACKGROUND
  The Australian Imaging, Biomarkers and Lifestyle (AIBL) Flagship Study of Ageing is a prospective study of 1,112 individuals (211 with Alzheimer's disease (AD), 133 with mild cognitive impairment (MCI), and 768 healthy controls (HCs)). Here we report diagnostic and cognitive findings at the first (18-month) follow-up of the cohort. The first aim was to compute rates of transition from HC to MCI, and MCI to AD. The second aim was to characterize the cognitive profiles of individuals who transitioned to a more severe disease stage compared with those who did not.
  
  
  METHODS
  Eighteen months after baseline, participants underwent comprehensive cognitive testing and diagnostic review, provided an 80 ml blood sample, and completed health and lifestyle questionnaires. A subgroup also underwent amyloid PET and MRI neuroimaging.
  
  
  RESULTS
  The diagnostic status of 89.9% of the cohorts was determined (972 were reassessed, 28 had died, and 112 did not return for reassessment). The 18-month cohort comprised 692 HCs, 82 MCI cases, 197 AD patients, and one Parkinson's disease dementia case. The transition rate from HC to MCI was 2.5%, and cognitive decline in HCs who transitioned to MCI was greatest in memory and naming domains compared to HCs who remained stable. The transition rate from MCI to AD was 30.5%.
  
  
  CONCLUSIONS
  There was a high retention rate after 18 months. Rates of transition from healthy aging to MCI, and MCI to AD, were consistent with established estimates. Follow-up of this cohort over longer periods will elucidate robust predictors of future cognitive decline.
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne; St. Vincent's Aged Psychiatry Service, St George's Hospital, Kew, Victoria, Australia.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
authors.affiliation: National Ageing Research Institute (NARI), Parkville, Victoria, Australia.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Szoeke
authors.affiliation: Florey Institute of Neuroscience and Mental Health (MHRI), Parkville, Victoria, Australia.
authors.forename: Ashley I
authors.initials: AI
authors.lastname: Bush
authors.affiliation: Florey Institute of Neuroscience and Mental Health (MHRI), Parkville, Victoria, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Darby
authors.affiliation: Macquarie University, Sydney, NSW, Australia.
authors.forename: Petra L
authors.initials: PL
authors.lastname: Graham
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne; St. Vincent's Aged Psychiatry Service, St George's Hospital, Kew, Victoria, Australia.
authors.forename: Nicola T
authors.initials: NT
authors.lastname: Lautenschlager
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Preventative Health Flagship, CMSE CMIS (CSIRO), Parkville, Victoria, Australia.
authors.forename: S Lance
authors.initials: SL
authors.lastname: Macaulay
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, WA, Australia.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.affiliation: CogState Limited, Melbourne, Victoria, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Maruff
authors.affiliation: Florey Institute of Neuroscience and Mental Health (MHRI), Parkville, Victoria, Australia.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Preventative Health Flagship, CMSE CMIS (CSIRO), Parkville, Victoria, Australia.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: McBride
authors.affiliation: Latrobe University, Melbourne, Victoria, Australia.
authors.forename: Kerryn E
authors.initials: KE
authors.lastname: Pike
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, WA, Australia.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Rainey-Smith
authors.affiliation: Florey Institute of Neuroscience and Mental Health (MHRI), Parkville, Victoria, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Rembach
authors.affiliation: Florey Institute of Neuroscience and Mental Health (MHRI), Parkville, Victoria, Australia.
authors.forename: Joanne
authors.initials: J
authors.lastname: Robertson
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: Macquarie University, Sydney, NSW, Australia.
authors.forename: Greg
authors.initials: G
authors.lastname: Savage
authors.affiliation: Florey Institute of Neuroscience and Mental Health (MHRI), Parkville, Victoria, Australia.
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.affiliation: Austin Health, Aged Care, Heidelberg, Victoria, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Woodward
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Preventative Health Flagship, CMSE CMIS (CSIRO), Parkville, Victoria, Australia.
authors.forename: William
authors.initials: W
authors.lastname: Wilson
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Preventative Health Flagship, CMSE CMIS (CSIRO), Parkville, Victoria, Australia.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne; St. Vincent's Aged Psychiatry Service, St George's Hospital, Kew, Victoria, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Ames
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000523:psychology; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis*; D001315:Australia; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003071:Cognition; D060825:Cognitive Dysfunction / Q000097:blood / Q000175:diagnosis*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008019:Life Style; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012959:Socioeconomic Factors
chemical_list: D015415:Biomarkers