[A proposal for application and scoring of the Clock Drawing Test in Alzheimer's disease].

Introduction: The Clock Drawing Test (CDT) has been used in recent years as a simple neuropsychological instrument to assess cognitive deterioration associated with dementia, even though uniform operative criteria with respect to its application and scoring have not been established.

Objective: To present application normatives and establish the most relevant psychometric criteria of the CDT in a sample of healthy subjects (HS) and patients with Alzheimer's disease (AD).

Patients And Methods: 56 patients were selected of which 35 were female and 21 were male. The patients' mean age was 72.7 with a standard deviation of 7.64. All of whom where probable AD patients according to the NINCDS-ADRDA criteria at stage 1 CDR. The group of HS was made up of 56 control subjects (34 female, 22 male) with a mean age of 72.14 and a standard deviation of 7.2. The CDT was applied in both its command (COM) and copy (COP) experimental conditions.

Results: The main psychometric parameters analysed in the studied series showed the following values: internal consistency (Cronbach's alpha coefficient 0.9029); cut off point CT COM 6 with 92.80, sensitivity; false negatives (FN) 7.2 with a specificity rating 93.48; false positive (FP) 6.52 with 93.16 efficacy; cut off point CT COP 8 with 73.11 sensitivity; FN 26.89 with 90.58 specificity; FP 9.42 with 82.49 efficacy.

Conclusion: The CDT can be used to discriminate between HS and those in the initial stages of AD in the given sample using the established application and scoring criteria.