Clock drawing performance in a community-dwelling population: Normative data for Japanese subjects

Objectives: The Clock Drawing Test (CDT) is commonly used for cognitive screening. The purpose of this study is to develop normative data for the CDT for the Japanese community-dwelling population, using the method of Freedman. This study also investigates the effect of demographic factors on the performance of the subjects in this task. Methods: We administered the CDT and the Mini-Mental State Examination (MMSE) to 873 volunteers. Using a multiple linear regression analysis, we found a gender difference in the free-drawn condition. Results: A detrimental effect of age was observed in the free-drawn and pre-drawn conditions. The years of education affected the CDT in the examiner 2 condition. Correlations of the MMSE with each of the five conditions of the CDT were significant, further validating this test. Conclusions: Our study provides preliminary normative data for the Japanese population stratified by the age and level of education. However, interpretation of our results was hampered by the large variability in the performance of the subjects and the possibility of a selection bias. Thus, additional studies will be necessary to further characterise the CDT scores for the Japanese community.