The Clock Drawing Test: Portuguese norms, by age and education, for three different scoring systems

The Clock Drawing Test has been systematically used to assess visuospatial deficits related to the parietal lobes, but we now acknowledge its much more complex relation with other cognitive abilities. Despite its common use in clinical and investigational practices, no study has developed normative data for the Portuguese population. We present the distribution of clock drawing scores using three scoring systems in a representative community sample of cognitively healthy subjects. We found that the systems were well correlated with each other and with cognitive screening tests widely used and had good psychometric properties. Normative data for the three scoring systems were developed considering age and education. These results allow a more rigorous interpretation of the test performance in clinical context and are especially relevant for epidemiological research.