title: Clock test deficits related to the global cognitive state in Alzheimer's and Parkinson's disease.
abstract: OBJECTIVE
  Clock drawing (CD) seems to be impaired quite early in the process of cognitive decline in Parkinson's disease (PD).
  
  
  METHODS
  We assessed performance on the CD test (CDT), clock setting test (CST) and clock reading test (CRT) in 32 elderly healthy controls, 41 patients with PD, 23 patients with amnestic mild cognitive impairment (aMCI) and 40 patients with Alzheimer's dementia (AD). Our focus was on comparing the performance of PD and aMCI/AD patients in relation to their global cognitive states (operationalized by the Mini Mental Status Examination). We also analyzed qualitative differences in errors of drawing, setting and reading clocks.
  
  
  RESULTS
  We found that performance in CDT, but not in the CST or CRT, was impaired earlier in PD than in aMCI/AD. Incorrect placement of the minute hand was the most prominent error in both patient groups. We found no specific influence of visuospatial dysfunction in PD on clock drawing.
  
  
  CONCLUSIONS
  Our findings suggest that executive function related to retrieval of semantic memory about the minute hand is compromised early in PD.
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Saur
authors.forename: Claudia
authors.initials: C
authors.lastname: Maier
authors.forename: Monika
authors.initials: M
authors.lastname: Milian
authors.forename: Ellen
authors.initials: E
authors.lastname: Riedel
authors.forename: Daniela
authors.initials: D
authors.lastname: Berg
authors.forename: Inga
authors.initials: I
authors.lastname: Liepelt-Scarfone
authors.forename: Thomas
authors.initials: T
authors.lastname: Leyhe
mesh_terms: D000368:Aged; D000465:Algorithms; D000544:Alzheimer Disease / Q000175:diagnosis / Q000523:psychology*; D003071:Cognition / Q000502:physiology*; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000523:psychology; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004522:Educational Status; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D009069:Movement Disorders / Q000209:etiology / Q000523:psychology; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000175:diagnosis / Q000523:psychology*; D013028:Space Perception / Q000502:physiology