The diagnostic value of drawing a clock in geriatrics

In this study the Clock Drawing Test (CDT) is used in a geriatric department to search for dementia in a population with somatic disorders (N=236). The demented group (N=113) has significant lower scores on every item and on the total score of the scoring method, compared to the non-demented group (N=123). A factor analysis of the scoring method shows that the fourteen items can be grouped into the three groups "contour", "digits", and "hands". A logistic regression shows that "hands" is the most discriminating, although this effect is moderate (sensitivity 59.3%, specificity 75.6%). Considering however that the CDT, compared to other screening tasks, appeals to an unique combination of cognitive functions, including visual semantic memory, working memory, visuospatial skills, attention and executive functions, it can be concluded that this test can contribute to the diagnoses of dementia, besides the traditionally used instruments.