title: A subtest analysis of the Montreal cognitive assessment (MoCA): which subtests can best discriminate between healthy controls, mild cognitive impairment and Alzheimer's disease?
abstract: BACKGROUND
  It is necessary to continue to explore the psychometric characteristics of key cognitive screening tests such as the Montreal Cognitive Assessment (MoCA) to diagnose cognitive decline as early as possible and to attend to the growing need of clinical trials involving mild cognitive impairment (MCI) participants. The main aim of this study was to assess which MoCA subtests could best discriminate between healthy controls (HC), participants with MCI, and Alzheimer's disease (AD).
  
  
  METHODS
  Cross-sectional analysis of 136 elderly with more than four years of education. All participants were submitted to detailed clinical, laboratory, and neuroimaging evaluation. The MoCA, Mini-Mental State Examination (MMSE), the Cambridge Cognitive Examination (CAMCOG), Geriatric Depression Scale (GDS), and Functional Activities Questionnaire (FAQ) were applied to all participants. The MoCA test was not used in the diagnostic procedure.
  
  
  RESULTS
  Median MoCA total scores were 27, 23 and 18 for HC, MCI, and AD, respectively (p < 0.001). Word repetition, inverse digits, serial 7, phrases, verbal fluency, abstraction, and word recall discriminated between MCI and HC participants (p < 0.001). The clock drawing, the rhino naming, delayed recall of five words and orientation discriminated between patients with MCI and AD (p < 0.001). A reduced version of the MoCA with only these items did not improve accuracy between MCI and HC (p = 0.076) or MCI and AD (p = 0.119).
  
  
  CONCLUSIONS
  Not all MoCA subtests might be fundamental to clinical diagnosis of MCI. The reduced versions of MoCA did not add diagnostic accuracy.
authors.affiliation: Department of Internal Medicine,Faculty of Medicine of Jundiaí,State of São Paulo,Brazil.
authors.forename: Juliana Francisco
authors.initials: JF
authors.lastname: Cecato
authors.affiliation: Department of Internal Medicine,Faculty of Medicine of Jundiaí,State of São Paulo,Brazil.
authors.forename: José Eduardo
authors.initials: JE
authors.lastname: Martinelli
authors.affiliation: Department of Statistics,Federal University of São Carlos (UFSCar),State of São Paulo,Brazil.
authors.forename: Rafael
authors.initials: R
authors.lastname: Izbicki
authors.affiliation: Department of Neurology,Faculty of Medicine,University of São Paulo,São Paulo,Brazil.
authors.forename: Mônica Sanches
authors.initials: MS
authors.lastname: Yassuda
authors.affiliation: Department of Internal Medicine,Faculty of Medicine of Jundiaí,State of São Paulo,Brazil.
authors.forename: Ivan
authors.initials: I
authors.lastname: Aprahamian
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis*; D001938:Brazil; D016022:Case-Control Studies; D003071:Cognition; D060825:Cognitive Dysfunction / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011939:Mental Recall; D059906:Neuroimaging; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics / Q000592:standards*; D012372:ROC Curve
keywords: Alzheimer’s disease; cognitive assessment; cognitive testing; mild cognitive impairment diagnosis