Do age and education contribute to performance on the clock drawing test? Normative data for the Greek population

Abstract

Our purpose in undertaking the present study was to develop norms for the Greek population for the Clock Drawing Test (CDT), using a systematic scoring procedure, and to explore the influence of demographic factors on the performance of healthy individuals. We administered the CDT to 223 healthy adults and scored it according to the method of Freedman et al. (1994). In 136 of the participants, we also measured global cognitive status with the Mini-Mental State Examination. We found that both age and level of education contributed to CDT performance. Interestingly, CDT performance was relatively consistent across the ages between 14-59 years, showing a marked decline after 60 and another decline after 70. Therefore, we concluded that CDT performance is relatively resistant to the effects of age for those below 60 years old. We present preliminary normative data for the Greek population stratified by age and level of education. Further research should include more extensive sampling of elderly participants (>60 years old) with varying levels of education, in order to establish more reliable norms for the elderly.