Clock drawing performance in cognitively normal elderly

Abstract

The Clock Drawing Test (CDT) is a common neuropsychological measure sensitive to cognitive changes and functional skills (e.g., driving test performance) among older adults. However, normative data have not been adequately developed. We report the distribution of CDT scores using three common scoring systems [Mendez, M. F., Ala, T., & Underwood, K. L. (1992). Development of scoring criteria for the Clock Drawing Task in Alzheimer's Disease. Journal of the American Geriatrics Society, 40, 1095-1099; Cahn, D. A., Salmon, D. P., Monsch, A. U., Butters, N., Wiederholt, W. C., & Corey-Bloom, J. (1996). Screening for dementia of the Alzheimer type in the community: The utility of the Clock Drawing Test. Archives of Clinical Neuropsychology, 11(6), 529-539], among 207 cognitively normal elderly. The systems were well correlated, took little time to use, and had high inter-rater reliability. We found statistically significant differences in CDT scores based on age and WRAT-3 Reading score, a marker of education quality. We present means, standard deviations, and t- and z-scores based on these subgroups. We found that "normal" CDT performance includes a wider distribution of scores than previously reported. Our results may serve as useful comparisons for clinicians wishing to know whether their patients perform in the general range of cognitively normal elderly.

Figure 1. Examples of qualitative differences detected by each scoring system

a. Received a low score (4) on Freund due to spacing and correction markings (rater considered this “intrusive marks”), but a “normal” score on the Mendez (18) and Cahn Global (9) scales. b. Received a perfect score on the Mendez scale (20) but missed points on Freund (6) and Cahn Global (8) due to spacing errors. c. Received a “normal” score on Freund (5) and Mendez (18), but a poor score on Cahn (5) because of clock face distortion and spacing errors. d. Received a “normal” score on Freund (5) and Mendez (19), but a low score on Cahn (4) due to spacing and incorrect hand placement.

Figure 2

The only “perfect clock” in the normative sample (receiving a perfect score on all three scoring systems).

Figure 3. Normative clock drawings featuring unique errors (using the Mendez scoring system)

a. One of three clocks that did not feature “a totally closed figure without gaps.” b. Only clock without “all hands … totally within a closure figure center” and “no repeated or duplicated number symbols” (note small “10” along hand pointing toward “2”). c. Only clock that did not have “three or more clock quadrants … [with] one or more appropriate numbers” and “most symbols…ordered in a clockwise or rightward direction.” d. Only clock without “all numbers 1–12…indicated.”