title: Clinical utility of the cogstate brief battery in identifying cognitive impairment in mild cognitive impairment and Alzheimer's disease.
abstract: BACKGROUND
  Previous studies have demonstrated the utility and sensitivity of the CogState Brief Battery (CBB) in detecting cognitive impairment in Alzheimer's disease (AD) and mild cognitive impairment (MCI) and in assessing cognitive changes in the preclinical stages of AD. Thus, the CBB may be a useful screening tool to assist in the management of cognitive function in clinical settings. In this study, we aimed to determine the utility of the CBB in identifying the nature and magnitude of cognitive impairments in MCI and AD.
  
  
  METHODS
  Healthy adults (n = 653) adults with amnestic MCI (n = 107), and adults with AD (n = 44) who completed the CBB participated in this study. Composite Psychomotor/Attention and Learning/Working Memory scores were computed from the individual CBB tests. Differences in composite scores were then examined between the three groups; and sensitivity and specificity analyses were conducted to determine cut scores for the composite scores that were optimal in identifying MCI- and AD-related cognitive impairment.
  
  
  RESULTS
  Large magnitude impairments in MCI (g = 2.2) and AD (g = 3.3) were identified for the learning/working memory composite, and smaller impairments were observed for the attention/psychomotor composite (g's = 0.5 and 1, respectively). The cut-score associated with optimal sensitivity and specificity in identifying MCI-related cognitive impairment on the learning/working memory composite was -1SD, and in the AD group, this optimal value was -1.7SD. Both composite scores showed high test-retest reliability (r = 0.95) over four months. Poorer performance on the memory composite was also associated with worse performance on the Mini Mental State Exam and increasing severity on the Clinical Dementia Rating Scale sum of boxes score.
  
  
  CONCLUSIONS
  Results of this study suggest that the CogState learning/working memory composite score is reduced significantly in CI and AD, correlate well with measures of disease classification and are useful in identifying memory impairment related to MCI- and AD.
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia ; CogState Ltd, Melbourne, Victoria Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Maruff
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Yen Ying
authors.initials: YY
authors.lastname: Lim
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia.
authors.forename: David
authors.initials: D
authors.lastname: Darby
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia ; Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Kew, Victoria Australia ; National Ageing Research Institute, Parkville, Victoria Australia.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, CT USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Pietrzak
authors.affiliation: Lifespan Hospital System & Department of Neurology, Warren Alpert Medical School of Brown University, Providence, RI USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Snyder
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Ashley I
authors.initials: AI
authors.lastname: Bush
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia ; National Ageing Research Institute, Parkville, Victoria Australia ; CSIRO Preventative Health Flagship, Parkville, Victoria Australia.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Szoeke
authors.affiliation: CogState Ltd, Melbourne, Victoria Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: Schembri
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Kew, Victoria Australia ; National Ageing Research Institute, Parkville, Victoria Australia.
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters