title: Diagnostic transitions in mild cognitive impairment subtypes.
abstract: BACKGROUND
  At least for a subset of patients, the clinical diagnosis of mild cognitive impairment (MCI) may represent an intermediate stage between normal aging and dementia. Nevertheless, the patterns of transition of cognitive states between normal cognitive aging and MCI to dementia are not well established. In this study we address the pattern of transitions between cognitive states in patients with MCI and healthy controls, prior to the conversion to dementia.
  
  
  METHODS
  139 subjects (78% women, mean age, 68.5 +/- 6.1 years; mean educational level, 11.7 +/- 5.4 years) were consecutively assessed in a memory clinic with a standardized clinical and neuropsychological protocol, and classified as cognitively healthy (normal controls) or with MCI (including subtypes) at baseline. These subjects underwent annual reassessments (mean duration of follow-up: 2.7 +/- 1.1 years), in which cognitive state was ascertained independently of prior diagnoses. The pattern of transitions of the cognitive state was determined by Markov chain analysis.
  
  
  RESULTS
  The transitions from one cognitive state to another varied substantially between MCI subtypes. Single-domain MCI (amnestic and non-amnestic) more frequently returned to normal cognitive state upon follow-up (22.5% and 21%, respectively). Among subjects who progressed to Alzheimer's disease (AD), the most common diagnosis immediately prior conversion was multiple-domain MCI (85%).
  
  
  CONCLUSIONS
  The clinical diagnosis of MCI and its subtypes yields groups of patients with heterogeneous patterns of transitions between one given cognitive state to another. The presence of more severe and widespread cognitive deficits, as indicated by the group of multiple-domain amnestic MCI may be a better predictor of AD than single-domain amnestic or non-amnestic deficits. These higher-risk individuals could probably be the best candidates for the development of preventive strategies and early treatment for the disease.
authors.affiliation: Department and Institute of Psychiatry, University of São Paulo, Brazil. forlenza@usp.br
authors.forename: Orestes Vicente
authors.initials: OV
authors.lastname: Forlenza
authors.forename: Breno Satler
authors.initials: BS
authors.lastname: Diniz
authors.forename: Paula Villela
authors.initials: PV
authors.lastname: Nunes
authors.forename: Claudia Maia
authors.initials: CM
authors.lastname: Memória
authors.forename: Monica Sanches
authors.initials: MS
authors.lastname: Yassuda
authors.forename: Wagner Farid
authors.initials: WF
authors.lastname: Gattaz
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D003072:Cognition Disorders / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011594:Psychometrics