Quantitative and Qualitative Analyses of the Clock Drawing Test in Mild Cognitive Impairment and Alzheimer Disease: Evaluation of a Modified Scoring System

Abstract

The clock drawing test (CDT) has been used as a screening tool for identifying cognitive decline in individuals with Alzheimer disease (AD) and other dementias but has not been extensively evaluated for categorizing individuals with mild cognitive impairment (MCI). This study used both an established quantitative scoring system and a revised scoring method based on qualitative error criteria developed by Rouleau et al to demonstrate the sensitivity of the CDT to MCI. Participants were 66 cognitively healthy older adult, 33 individuals with MCI, and 33 individuals with AD. Sensitivity analyses of the 2 clock drawing methods revealed that the Modified Rouleau scoring method was more sensitive to MCI than the original Rouleau scoring system. Conceptual, graphic, and spatial-planning difficulties were the most commonly committed errors on the CDT across all groups, and conceptual errors along with graphic difficulties were committed more often in the MCI group than the cognitively healthy control group. Participants in the AD group exhibited greater deficits in all error categories and significantly lower total CDT scores compared to both the MCI and older adult controls. Findings observed in this study suggest that qualitative observations of clock drawing errors can help increase sensitivity of the CDT to MCI and that use of a more detailed scoring system is necessary to differentiate individuals with MCI from cognitively healthy older adults.