title: Discrimination of dementia with lewy bodies from Alzheimer disease and Parkinson disease using the clock drawing test.
abstract: OBJECTIVE
  The authors' objective was to examine the ability of the Clock Drawing Test to discriminate Dementia with Lewy bodies from Alzheimer disease and Parkinson disease.
  
  
  BACKGROUND
  Recent advances in medical treatments for dementia underscore the importance of differentiating among dementia subtypes. Clinically, Dementia with Lewy bodies can often be difficult to discriminate from Alzheimer disease and Parkinson disease because of similar and overlapping cognitive and motor features. While the Clock Drawing Test has been shown to discriminate dementia from normal aging fairly accurately, less is known about its ability to discriminate between various dementia groups.
  
  
  METHODS
  Patients with Alzheimer disease (n = 22), patients with cognitively impaired Parkinson disease (n = 17), and patients with Dementia with Lewy bodies (n = 20), matched for age, education, and dementia severity, were compared on the Clock Drawing Test, scored for overall accuracy as well as the presence of specific error types.
  
  
  RESULTS
  There were no significant group differences on a global quantitative measure of Clock Drawing Test performance. With regard to differences on the error types evaluated, the patients with Dementia with Lewy bodies were more likely to make conceptual errors than the patients with Alzheimer disease and Parkinson disease, and the patients with Parkinson disease and Dementia with Lewy bodies made more planning errors than the patients with Alzheimer disease. Classification accuracy was fair, with 69% overall classification for Alzheimer disease versus Dementia with Lewy bodies, and 68% overall classification for Parkinson disease versus Dementia with Lewy bodies.
  
  
  CONCLUSIONS
  Although some differences may exist in the qualitative features of clock drawing performance between these patient groups, overall clock drawing performance is relatively similar, and as a single instrument, the Clock Drawing Test provides limited discrimination of Dementia with Lewy bodies from Alzheimer disease and Parkinson disease.
authors.affiliation: Department of Psychiatry and Human Behavior, Brown Medical School, Memorial Hospital of Rhode Island, USA. Deborah_Weiner@brown.edu
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Cahn-Weiner
authors.forename: Karren
authors.initials: K
authors.lastname: Williams
authors.forename: Janet
authors.initials: J
authors.lastname: Grace
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Tremont
authors.forename: Holly
authors.initials: H
authors.lastname: Westervelt
authors.forename: Robert A
authors.initials: RA
authors.lastname: Stern
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D020961:Lewy Body Disease / Q000175:diagnosis* / Q000523:psychology; D008297:Male; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000175:diagnosis* / Q000523:psychology; D013647:Task Performance and Analysis