title: Cognitive functioning of individuals aged 90 years and older without dementia: A systematic review.
abstract: BACKGROUND
  Reference values to define cognitive impairment in individuals aged 90 years and older are lacking. We systematically reviewed the literature to determine the level of cognitive functioning of individuals aged 90 years and older without dementia.
  
  
  METHODS
  The search identified 3972 articles of which 20 articles were included in the review. We calculated mean cognitive test scores and cut-off scores for cognitive tests published in two or more articles.
  
  
  RESULTS
  The mean cognitive test scores (SD)/cut-off scores for individuals aged 90 years and older without dementia of the five most commonly used cognitive tests were: MMSE: 26.6 (2.6)/23.3 points, Digit Span forward: 5.9 (1.8)/3.6 digits, Digit Span backward: 4.4 (1.6)/2.4 digits, TMT-A: 85.8 (42.5)/140.2s and TMT-B: 220.3 (99.2)/347.3s.
  
  
  CONCLUSIONS
  We provided mean cognitive test scores and cut-off scores that will improve the diagnostic process of cognitive impairment in individuals aged 90 years and older.
authors.affiliation: Alzheimer Center & Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: n.legdeur@vumc.nl.
authors.forename: N
authors.initials: N
authors.lastname: Legdeur
authors.affiliation: Department of Clinical Neuropsychology, Vrije Universiteit Amsterdam, The Netherlands.
authors.forename: T T
authors.initials: TT
authors.lastname: Binnekade
authors.affiliation: Medical Library, Vrije Universiteit Amsterdam, The Netherlands.
authors.forename: R H
authors.initials: RH
authors.lastname: Otten
authors.affiliation: Alzheimer Center & Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Badissi
authors.affiliation: Alzheimer Center & Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Scheltens
authors.affiliation: Alzheimer Center & Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands; Department of Psychiatry & Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
authors.forename: P J
authors.initials: PJ
authors.lastname: Visser
authors.affiliation: Department of Medicine and Aged Care, Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia; MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, Vrije Universiteit Amsterdam, The Netherlands.
authors.forename: A B
authors.initials: AB
authors.lastname: Maier
mesh_terms: D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology / Q000523:psychology*; D003071:Cognition / Q000502:physiology*; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000523:psychology; D003704:Dementia / Q000175:diagnosis / Q000523:psychology; D004522:Educational Status; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests
keywords: Cognitive functioning; Cognitive impairment; Healthy ageing; Individuals aged 90 years and older; Nonagenarians; Reference values