title: Optimizing mild cognitive impairment for discriminating dementia risk in the general older population.
abstract: BACKGROUND
  Criteria for mild cognitive impairment (MCI) predict dementia risk in the clinic. Dementia risk in the population is different and whether there is an optimal MCI-derived threshold for discriminating at-risk from not-at-risk cases in the general older population is not known.
  
  
  METHODS
  Data were from the Medical Research Council Cognitive Function and Ageing Study. Two risk thresholds were derived from each of seven different concepts of MCI including: Mayo Clinic-defined amnestic, nonamnestic, multiple, and revised MCI, MCI based on Mini-Mental State Examination derived categories, and the definitions of Cognitive Impairment No Dementia and Age-Related Cognitive Decline (ARCD). Receiver operating characteristic analysis was used to compare the predictive validity of 2-year incident dementia for each risk threshold across the different MCI definitions.
  
  
  RESULTS
  MCI-derived risk thresholds varied in their ability to predict dementia. MCI thresholds were accurate in identifying individuals not at-risk of dementia progression (false-negative range: 0%–3.4%). No MCI-derived threshold accurately identified an at-risk group with a 2-year progression rate greater than 20%. Criteria for ARCD defined the threshold with the highest sensitivity and specificity for dementia conversion.
  
  
  CONCLUSIONS
  MCI-derived thresholds do not reliably identify individuals at-risk of incident dementia at 2 years when applied in the general population. A large subpopulation of individuals not at-risk was more reliably identified. What is considered a sufficient level of accuracy for identification of individuals at increased risk of dementia depends on the motivation for screening and on the safety and efficacy of available interventions.
authors.affiliation: Department of Public Health and Primary Care, Institute of Public Health, Cambridge, UK.
authors.forename: Blossom C M
authors.initials: BC
authors.lastname: Stephan
authors.forename: George M
authors.initials: GM
authors.lastname: Savva
authors.forename: Carol
authors.initials: C
authors.lastname: Brayne
authors.forename: John
authors.initials: J
authors.lastname: Bond
authors.forename: Ian G
authors.initials: IG
authors.lastname: McKeith
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Matthews
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology; D000368:Aged; D003072:Cognition Disorders / Q000175:diagnosis*; D003704:Dementia / Q000175:diagnosis* / Q000453:epidemiology; D003937:Diagnosis, Differential; D018450:Disease Progression; D006801:Humans; D015994:Incidence; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D012372:ROC Curve; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology