title: A typology of sub-clinical senescent cognitive disorder.
abstract: BACKGROUND
  Cognitive impairment without dementia is commonly observed in ageing populations. The present study aims to describe types of impairment and evolution over a one-year period.
  
  
  METHODS
  Three hundred and ninety-seven normal French elderly persons demonstrating recent, observable change in cognitive performance were examined annually using a computerised cognitive examination.
  
  
  RESULTS
  Five subtypes were differentiated by cluster analysis. Two of the groups were predicted by logistic regression to be at high risk of senile dementia. Of 16 incident cases of senile dementia diagnosed in the following year, 13 were found to have derived from these two groups. The typology was also found to be useful in the description of age-associated memory impairment.
  
  
  CONCLUSIONS
  Subclinical cognitive impairment was found to not constitute a unitary phenomenon and heterogeneous subgroups could be differentiated. The concept of 'normality' in elderly cohorts is reconsidered in the light of these findings.
authors.affiliation: INSERM Equipe Vieillissement cognitil, CRLC Val d'Aurelle, Montpellie.
authors.forename: K
authors.initials: K
authors.lastname: Ritchie
authors.forename: D
authors.initials: D
authors.lastname: Leibovici
authors.forename: B
authors.initials: B
authors.lastname: Ledésert
authors.forename: J
authors.initials: J
authors.lastname: Touchon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D003704:Dementia / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D005602:France; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011939:Mental Recall; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011594:Psychometrics; D012307:Risk Factors