title: Severity of cognitive impairment and the clinical diagnosis of AD with Lewy bodies.
abstract: OBJECTIVE
  1) To examine the clinical differences between AD and AD with Lewy bodies (AD+LB); and 2) to determine the accuracy of Consensus guidelines for the clinical diagnosis of dementia with Lewy bodies (DLB) at different levels of dementia severity.
  
  
  METHODS
  The authors examined the clinical characteristics of 185 patients with pathologically diagnosed AD alone and 60 with AD+LB. The relationship between clinical symptoms and AD+LB was determined by multivariate analyses, controlled by age, duration of symptoms, presence of cerebrovascular disease, and dementia severity.
  
  
  RESULTS
  Mild dementia syndrome: No specific clinical symptom was associated with the presence of AD+LB. The sensitivity of the diagnosis of DLB was 62% and specificity was 54%. Moderate dementia syndrome: Extrapyramidal signs (EPS), especially cogwheel rigidity, and major depression were associated with AD+LB. The sensitivity for DLB was 82% and specificity was 31%. Severe dementia syndrome: Cogwheel rigidity and diurnal hypersomnia were associated with AD+LB. The sensitivity for DLB was 93% and specificity was 16%.
  
  
  CONCLUSIONS
  The presence of EPS is not useful in differentiating AD+LB from AD in patients with mild dementia. However, as the disease progressed, they emerge as defining features, especially cogwheel rigidity. The accuracy of AD+LB diagnosis varies according the severity of the dementia syndrome. The low sensitivity and specificity in AD+LB patients with mild dementia suggest that in early stages AD+LB patients do not present the clinical characteristics of DLB. By contrast, the high sensitivity and low specificity for the diagnosis of DLB in moderate/severe dementia stages suggests that AD patients can also have characteristic symptoms of DLB. These results indicate that the antemortem diagnosis of AD+LB is difficult in all dementia stages, and better clinical and biologic differentiations of these entities are needed.
authors.affiliation: Department of Neurology, Alzheimer's Disease Research Center, University of Pittsburgh School of Medicine, PA, USA.
authors.forename: O L
authors.initials: OL
authors.lastname: Lopez
authors.forename: R L
authors.initials: RL
authors.lastname: Hamilton
authors.forename: J T
authors.initials: JT
authors.lastname: Becker
authors.forename: S
authors.initials: S
authors.lastname: Wisniewski
authors.forename: D I
authors.initials: DI
authors.lastname: Kaufer
authors.forename: S T
authors.initials: ST
authors.lastname: DeKosky
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000473:pathology; D001480:Basal Ganglia Diseases / Q000175:diagnosis / Q000473:pathology; D001921:Brain / Q000473:pathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D016631:Lewy Bodies / Q000473:pathology*; D020961:Lewy Body Disease / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D017410:Practice Guidelines as Topic; D011569:Psychiatric Status Rating Scales