Performance of three clock scoring systems across different ranges of dementia severity

The ability of three different Clock Drawing Test (CDT) scoring systems to detect Dementia of the Alzheimer Type (DAT) was investigated. As part of a neuropsychological battery, fifty DAT Type patients and fifty matched controls drew a clock. Each drawing was scored by three independent raters according to three different scoring systems: the 3-Factor system, the Template system, and the Abbreviated system. The CDT scoring systems were able to detect Dementia of the Alzheimer Type when the disease was moderate to severe, but lacked sensitivity in milder dementia. Animal Fluency was a better single predictor of dementia. Clinicians are advised to interpret the results of the Clock Drawing Test cautiously in an outpatient setting, where milder forms of dementia and low base rates are likely.