Clock-drawing Test and Cube-copying Test to Quickly Screen Dementia: In Combination with the Mini-mental State Examination Scores

Abstract

Objective Due to the increasing elderly population and number of dementia patients, the current number of psychiatrists and neurologists remains insufficient to treat dementia in Japan. Therefore, a simple method for accurately performing a dementia diagnosis, including that of primary care physicians, is sought in clinical practice. Methods A retrospective study was conducted on patients who made their first visit due to amnesia between October 2020 and October 2022. The sensitivities and specificities of four spatial recognition and planning ability evaluation methods [fox finger imitation test, pentagon-copying test (PCT), cube-copying test (CCT), and clock-drawing test (CDT)] were calculated. The difference between the Mini-mental State Examination (MMSE) scores, as an evaluation of memory and language impairment, and CDT scores were assessed using the Mann-Whitney U test. Patients Fifty-one patients with dementia and 6 patients without dementia were examined in this study. Results The sensitivity and specificity were 31.4% and 100% for the fox finger imitation tests, 29.4% and 100% for PCT, 62% and 83.3% for CCT, and 72.5% and 100% for CDT, respectively. The sensitivity increased to 78.4% when the CCT and CDT results were combined. Spearman's rank correlation coefficient between the MMSE and CDT scores of the 51 patients with dementia showed a significantly positive correlation (r=0.62, p<0.001). Comparing Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), the difference between the MMSE and CDT scores was significantly greater in patients with DLB. Conclusion To quickly screen for dementia, a combination of CCT and CDT is recommended for the highest sensitivity (78.4%). In addition, the difference between the CDT and MMSE scores is considered to be useful for differentiating DLB from AD.

Keywords: Alzheimer's disease; clock-drawing test; cube-copying test; dementia; dementia with Lewy bodies; fox finger imitation test.

Figure 1.

The clock-drawing test (CDT) score relative to the mini-mental-state examination (MMSE) score of 51 dementia patients. A significant positive correlation (r=0.62, p<0.001) was noted between the CDT and MMSE scores.

Figure 2.

Subtraction of the clock-drawing test (CDT) scores from the mini-mental-state examination (MMSE) scores. Subtraction of the CDT scores from the MMSE scores in the Alzheimer’s disease (AD) group (n=41) and dementia with Lewy bodies (DLB) group (n=3) resulted in significantly higher values in the DLB group. When the Mann-Whitney U test was performed, the minimum score for each: 4.5 points for AD; 12.5 points, DLB, the first quartile: 8.0 points for AD; 14.5 points, DLB; the median: 11 points for AD; 16.5 points, DLB; the third quartile: 13 points for AD; 17 points, DLB; the maximum value: 19.5 points for AD; 17.5 points, DLB, and p-value was 0.03, thus indicating significantly higher values with DLB.