title: Stage-independent and stage-specific phenotypic differences between vascular dementia and Alzheimer's Disease.
abstract: OBJECTIVE
  We examined the effect of stratification by dementia severity on clinical and neuropsychological differences observed between vascular dementia (VaD) and Alzheimer's disease (AD) to ascertain whether any observed phenotypic differences would differ between the early and late stages.
  
  
  METHODS
  The phenotypic features at presentation of 219 newly diagnosed VaD (n = 103) and AD (n = 116) patients were analyzed. All patients underwent clinical, neuropsychological and neuroimaging evaluation. Severity of dementia was staged using the Clinical Dementia Rating (CDR) scale.
  
  
  RESULTS
  VaD can be clinically distinguished from AD by criterion-related features that span across all stages of dementia. We also identified non-criterion-related features that differed according to dementia severity. In the CDR 0.5-1 stage, VaD patients demonstrated increased reading difficulty, loss of insight, apathy, and greater impairment in executive function compared with delayed and recognition memory. Unique distinguishing features for VaD in the CDR 2-3 stage included higher Geriatric Depression Scale scores, lower Barthel scores, gait apraxia and parkinsonism.
  
  
  CONCLUSIONS
  Phenotypic differences between VaD and AD can be conceptualized as either criterion-related stage-independent features, or stage-specific features (comprising cognitive and neuropsychological elements in the mild stages, and physical, affective and functional components in the later stages).
authors.affiliation: Department of Geriatric Medicine, Tan Tock Seng Hospital, Singapore. peng_chew_chan@ttsh.com.sg
authors.forename: Mark
authors.initials: M
authors.lastname: Chan
authors.forename: Wee Shiong
authors.initials: WS
authors.lastname: Lim
authors.forename: Suresh
authors.initials: S
authors.lastname: Sahadevan
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology*; D015140:Dementia, Vascular / Q000175:diagnosis* / Q000523:psychology*; D003863:Depression / Q000523:psychology; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D020235:Gait Apraxia / Q000209:etiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D020734:Parkinsonian Disorders / Q000523:psychology; D010641:Phenotype; D011569:Psychiatric Status Rating Scales; D012959:Socioeconomic Factors