The Clock Drawing Test: A review of its accuracy in screening for dementia

The Clock Drawing Test (CDT) is a simple neuropsychometric instrument that can be easily applied to assess several cognitive functions. Over the past 20 years, the CDT has aroused considerable interest in its role for the early screening of cognitive impairment, especially in dementia. Although the CDT is considered an accurate test for dementia screening, recent studies including comparisons with structured batteries such as the CAMCOG have shown mixed results. Objectives To investigate the importance of the CDT compared to other commonly used tests, in the diagnosis of dementia in the elderly; (2) to evaluate the reliability and correlation between available CDT scoring scales from recent studies. Methods A systematic search in the literature was conducted in September 2008 for studies comparing CDT scoring systems and comparing the CDT with neuropsychiatric batteries. Results Twelve studies were selected for analyses. Seven of these studies compared CDT scoring scales while five compared the CDT against the CAMCOG and the MMSE. Eight studies found good correlation and reliability between the scales and the other tests. Conclusion Despite the mixed results in these studies, the CDT appears to be a good screening test for dementia.