Clock-Face Drawing, Reading and Setting Tests in the Screening of Dementia in Chinese Elderly Adults

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1 Journal of Gerontology: PSYCHOLOGICAL SCIENCES 1998, Vol. 53B, No. 6, P353-P357 Copyright 1998 by The Gerontological Society of America Clock-Face Drawing, Reading and Setting Tests in the Screening of Dementia in Chinese Elderly Adults Linda Chiu Wa Lam, 1 Helen Fung Kum Chiu, 1 Kei On Ng, 1 Calais Chan, 1 Wan Fat Chan, 2 Siu Wah Li, 3 and Mary Wong 2 'Department of Psychiatry, The Chinese University of Hong Kong. 2 Pamela Youde Nethersole Eastern Hospital, Hong Kong. 3 Castle Peak Hospital, Hong Kong. Comprehensive neuropsychological batteries focus on the subtle cognitive deficits in dementia, but a brief screening instrument is also of immense practical value. As the clock-drawing test encompasses a number of cognitive domains frequently disturbed by the dementing process, it is considered to be a suitable screening instrument for the disorder. We documented the usefulness of a new scoring method of the clock-drawing test for screening of dementia in the elderly Chinese in Hong Kong. Fifty-three demented individuals and 53 healthy elderly controls were assessed. At a cutoff score of, the sensitivity and specificity of the clock-drawing test in screening of dementia was 83% and 79%. With a composite test of clock reading and clock setting, the positive predictive value of the clock face test was 98%. This new scoring method of clock-drawing proved to be a valid measure for screening of dementia. It is applicable in non-english speaking populations and should be a useful adjunct for quick screening assessment of dementia. HHHE clock-drawing test was originally described in the A assessment of parietal lobe dysfunction (Critchley, 1953). However, the drawing of a clock face involves many psychological functions such as orientation and conceptualization of time, visual spatial organization, hemi-neglect and agraphia. As many of these processes are affected in people with dementia, the test was also considered to be a useful screening instrument for the disorder. Conventionally, clock-drawing patterns are analyzed with two different approaches. Some authors interpreted the result of clock drawing tests from a qualitative approach (Mendez, Ala, & Underwood, 1992; Shulman, Shedletsky, & Silver, 1986; Wolf-Klein, Silverstone, Levy, Brod, & Breuer, 1989). Common clock-drawing errors identified in Alzheimer's disease patients include perseveration, absence of numbers, counterclockwise rotation, irrelevant spatial arrangement and figures. Other authors, however, analyze clock drawing with a quantitative dimension; errors are assessed with predetermined criteria graded with severity (Sunderland et al., 1989; Tuokko, Hadjistaropoulos, Miller, & Beattie, 1992; Watson, Arfkeen, & Birge, 1993). In most of the reports, the principles by which the scoring criteria were derived have not been clearly documented. Moreover, owing to the use of different scoring methods, sensitivity and specificity differ substantially. Hence, comparison of results across different studies may be difficult (Brodaty & Moore, 1997). In this report, we aim to examine the usefulness of the clock-face test as a screening test for dementia in Hong Kong. A new scoring method specifically designed for use in the elderly population with a relatively low educational level was developed. To supplement the drawing test, we have also incorporated the clock-reading and setting tasks into the assessment. The validity and potential applications of the clock-drawing, setting and reading tests are reported and discussed. METHOD Participants Participants were recruited from a social center for elderly adults, an old-age home, and psychogeriatric outpatient clinics in Hong Kong. The criteria for inclusion were age 60 years or older, absence of significant neurological and psychiatric disorders apart from primary degenerative dementia, and consent for participation. Persons with severe blindness and impairment in hand function that would prevent drawing a clock-face properly were excluded. Approval from an ethics committee was obtained. One hundred and six Chinese adults participated in the study. The mean age was (SD = 7.90) years and mean educational level was 4.02 (SD = 4.47) years. Assessment Controls were recruited from a social center where participants were independently living community dwellers. All subjects underwent a comprehensive clinical interview and neurological examination by qualified psychiatrists to ascertain the presence or absence of dementia and its subtypes with DSM-IV criteria (American Psychiatric Association, 1994). A research assistant blind to the psychiatric status performed a subsequent interview. Assessment included the Chinese versions of the Mini-Mental State Examination (CMMSE; Chiu, Lee, Chung, & Kwong, 1994), the Blessed-Roth dementia scale (CDS; Lam et al., 1997), the Hamilton depression-rating scale (CHDRS; Zheng et al., 1988) and the clock-face drawing, reading and setting test. P353

2 P354 LAMETAL. Clock-Face Testing Procedure The clock-face tests consisted of three parts. The first part was comprised of the clock-drawing test: Participants were asked to fill inside a predrawn circle of 2.5" diameter the numbers of a clock face with arms indicating the 3 o'clock position. The instruction was repeated if the person could not understand the command. There was no time limit for completion of the drawing task. Clock-face drawing scores ranged from The scoring criteria were derived from several basic principles. First, a quantitative approach was adopted, with increasing scores indicating increasing severity of errors. Second, in order to improve the validity of the clock-drawing test in the local population where a majority of the elders had received little formal education, the legibility of characters and numbers was not scored. Third, we assumed that the conceptualization of time was a more fundamental and important function than other cognitive domains emphasizing constructional skills. Signs indicating that the subject attempted to denote the correct time were scored with greater weight than the subject's ability to draw. The scoring criteria are listed in the Appendix. Twenty subjects were selected randomly and assessed by two independent raters for interrater reliability. In the second part of the test, participants were asked to read the time from a toy clock of 3" diameter with arms indicating 6:30, 8:15, and 9 o'clock positions. They were then requested to complete the third part of the clock-face test, which involved setting the time using the arms of the same toy clock to indicate 7, 10:15 and 12:30 o'clock positions. The total number of wrong responses from clock reading and setting was recorded (0 = no error; 6 = 6 errors in clock setting and reading). RESULTS Fifty-three participants were considered to be cognitively intact, 39 were diagnosed as suffering from Alzheimer's disease, and 14 were diagnosed as suffering from non- Alzheimer's dementia. Using the DSM-III-R guidelines for the assessment of severity (American Psychiatric Association, 1987), 44% were mildly demented, 40% were moderately demented, and 13% were severely demented. The control group was significantly younger (mean age = years, SD = 6.70 years; mean age of demented subjects = years, SD = 8.70 years; t = 2A9,p<.05). No significant difference in sex (x 2 >.05) and educational level (t = -1.67, p >.05) was found between demented and control subjects. None of them were clinically depressed. The mean scores of the CHDRS were 4.07 (SD = 2.70) in normal controls and 3.05 (SD = 3.74) in demented subjects, respectively. Clinical Correlates of Clock-Drawing Test Clock-drawing scores correlated significantly with educational level (r = -.44, p <.001) and age (r =.42, p <.001). When demented and control subjects were analyzed separately, clock-drawing scores correlated significantly with educational level in demented subjects (r = -.63, p <.001) but not in controls (r = -.26, p >.05). The correlation with age, however, remained significant in both groups. Compared with other assessment tools, clock-drawing scores correlated significantly with the CDS scores (r =.60, p <.001) and CMMSE scores (r = -.73, p <.001). The correlations between clock-drawing scores and CMMSE (partial correlation, r = -.65, p <.001) and CDS (partial correlation, r =.60, p <.001) remained significant when the effects of age and education were controlled. The clock-drawing scores differentiated demented participants of different diagnoses from the elderly controls (oneway ANOVA, F(2,100) = 40.02, p <.001). Post hoc multiple comparisons with Bonferroni tests revealed that elderly controls scored significantly better than subjects with Alzheimer's disease (p <.001) and vascular dementia (p <.001). No significant difference was found in the clockdrawing scores between participants with Alzheimer's disease and those with non-alzheimer's dementia (p >.05). The difference remained significant when the effects of age and education were controlled for as covariates (F = 38.05, p <.001). When the severity of dementia was taken into account, scores of control subjects were significantly different from patients of all severity groups (one-way ANOVA, F(3,101) = 33.57, p <.0001). Post hoc multiple comparisons with Bonferroni test revealed that mildly demented participants scored significantly better than subjects with severe dementia (p <.05). No difference in clock-drawing scores was found between moderately and severely demented subjects. In addition to a total score, the clock-drawing test also provided qualitative information concerning specific psychological impairments. For example, one participant showed left-sided neglect, another demonstrated left-right disorientation with counterclockwise rotation, and two lost the ability to draw a clock face and wrote down the Chinese characters for 3 o'clock on the circle instead of drawing a clock. Screening for Dementia The clock-drawing scores were compared against clinical diagnosis of dementia. The sensitivity and specificity in screening for dementia are depicted in Table 1. In the assessment of interrater reliability, the correlation between ratings of the two raters was significant (r =.94, p <.001). The intraclass correlation coefficient is.88, indicating satisfactory interrater reliability. The combined scores of clock reading and setting errors were also compared against clinical diagnosis of dementia; sensitivity and specificity of the scores at different cut points are tabulated in Table 2. The results suggest that the clock reading and setting test is an instrument with low sen- Table 1. Sensitivity and Specificity of Clock-Drawing Tests in Screening for Dementia at Different Cut Points Cut Points Sensitivity Specificity * 5/6 "Optimal cut point. 92% 87% 83% 79% 77% 45% 68% 79% 83% 85%

3 CLOCK DRAWING TEST IN DEMENTIA SCREENING P355 Table 2. Sensitivity and Specificity of Clock Setting and Reading Tests in Screening for Dementia at Different Cut Points Cut Points Sensitivity Specificity 0/1 66% 56% 46% 40% 32% 95% 100% sitivity and high specificity. The clock drawing test was also combined with clock reading and setting. The positive predictive values at different combinations of cut points are illustrated in Table 3. At a cut point of, the clock-drawing test had a sensitivity of 83% and specificity of 79%. Combined with clock reading and setting tests (cut point of ), a positive predictive value of 98% was achieved. DISCUSSION The strong correlation with CMMSE and CDS, as well as the high sensitivity and specificity, suggests that the clock-face drawing test is a valid instrument in differentiating demented from nondemented adults. Although the clock-drawing test has repeatedly been reported as a feasible screening tool for cognitive impairment, unified criteria for scoring are not available. Different emphases on clockdrawing errors have hindered the standardization of scoring criteria. In order to develop a standardized measurement, we attempted to derive a new scoring method for the clockdrawing test with special attention to an elderly population with a relatively low educational level. Explicit instructions that legibility of letters would not be scored were stated to reduce potential bias against subjects who could not write properly. In addition, we attempted to set a prior assumption concerning relative severity of the clock errors. Conceptualization of time requires a certain level of intact orientation, vigilance, comprehension, and organization. The ability of a person to convert the time concept into the drawing of a clock face is likely to be related to the frontal executive control function and is hence considered to be a fundamental function. Other constructional skills like visual spatial organization, hemi-neglect, and dysgraphia are modular and consequently carried less weight in the scoring. It was hoped that such assumptions could meaningfully reflect the fundamental cognitive impairment in dementia. Shulman, Gold, Cohen, and Zucchero (1993) documented the deterioration in clock-drawing performance in a longitudinal study of demented subjects in the community. Although our sample was studied on a cross-sectional basis, the significant differences in scores among demented subjects of different severities also suggested that the test may be used as an indicator of progressive cognitive decline in follow-up studies. Some studies suggested that there were qualitative differences in clock-drawing errors in different types of dementia (Gnanalingham, Byrne, & Thornton, 1996; Rouleau, Salmon, Butters, Kennedy, & McGuire, 1992). In our study, the scores between subjects with Alzheimer's disease and non-alzheimer's (mostly vascular) Table 3. Positive and Negative Predictive Values at Different Cut Points in Combined Clock Drawing, Reading and Setting Tests Cut Point (Clock Drawing) * *Optimal cut point. Cut Point (Clock Reading and Setting) Positive Predictive Value dementia were not significantly different. Because of the limited number of subjects with other dementia syndromes, we did not look into the qualitative differences specifically. However, as the clock-drawing test is sensitive to both abstract ability and constructional functions, it is likely to be useful in distinguishing qualitative differences across different types of cortical and noncortical dementia. There are a number of limitations in our study that need to be addressed. Our control sample was drawn from volunteers attending a social center for elderly adults. Although they were living independently, there was still a slight chance that some isolated cognitive impairment might have escaped the attention of the screening psychiatrists. However, it is unlikely that diagnosable dementia syndrome would have been missed with the comprehensive clinical and neurological assessments. Second, the possibility of mood symptoms affecting clock-drawing performance needs to be addressed. In our study, we screened carefully for depressive symptoms to ensure that none of the participants were depressed. Third, the clock-drawing test is not as education-unbiased as initially assumed. Ainslie and Murden (1993) documented that clock-drawing performance is highly correlated with educational level. In our sample, we attempted to reduce the effects of education by deliberately disregarding the legibility of characters. Although the correlation was not significant in the controls, clock-drawing scores were still significantly correlated with educational level in demented participants. It is possible that in nondemented elderly adults, clock drawing was a simple test with ceiling effects readily achieved. In demented subjects, the ceiling effect was lost and education became a protective factor. Our scoring schedule represented an improvement in that the effect of education was only demonstrated in demented subjects. Future studies with larger sample sizes are needed to explore the effect of educational level on clock-drawing performance. Fourth, although giving specific hints on a number of psychological functions, the clock-drawing scores do not indicate the degree of memory impairment. Fifth, clock drawing requires that the subject be able to manipulate a pen. For patients

4 P356 LAMETAL. with hemiparesis, gross tremor, or defects in hand functioning, the clock-drawing test could not be performed reliably. In a further attempt to modify the use of the clock-face test in a population with low educational level, we tried to incorporate the clock reading and setting tests. The results suggested that clock reading and setting tasks are relatively easy: about one third of the demented participants made no error in the tests. As a result, the test has a low sensitivity, albeit with a high specificity. On its own, the clock reading and setting test is not a suitable instrument for screening for dementia because a large proportion of demented subjects would be missed due to the low sensitivity. We have combined the clock drawing, reading and setting scores in a two-stage design. The clock drawing test was first used as a screening test for dementia. Scores from subjects above the cut point for dementia were then assessed with clock reading and setting. Because the latter was a test with good specificity, a high positive predictive value for the two tests combined could be achieved. Our experience with using the clock-face test in Hong Kong suggests that it is a satisfactory test for screening for dementia. Because of easy administration and user friendliness, the test should be applicable in elderly populations where a relatively low educational level is expected. It is hoped that the new scoring criteria for clock drawing and the composite test with clock reading and setting can provide more elaborate information on the characteristics of clock-face tests and help to develop a more unified scoring method for comparison. ACKNOWLEDGMENT Address correspondence to Dr. Linda C. W. Lam, Department of Psychiatry, Prince of Wales Hospital, Shatin, NT, Hong Kong. cwlam@cuhk.edu.hk REFERENCES Ainslie, N. K., & Murden, R. A. (1993). Effect of education on the clockdrawing dementia screen in nondemented elderly persons. Journal of the American Geriatrics Society, 41, American Psychiatric Association. (1987). Diagnostic and Statistical Manual-III-R. Washington, DC: Author. American Psychiatric Association. (1994). Diagnostic and Statistical Manual-IV. Washington, DC: Author. Brodaty, H., & Moore, C. M. (1997). The clock-drawing test for dementia of the Alzheimer's type: A comparison of three scoring methods in a memory disorders clinic. International Journal of Geriatric Psychiatry, 72, Chiu, H. F. K., Lee, H. C, Chung, W. S., & Kwong, P. K. (1994). Reliability and validity of the Cantonese version of the Mini-Mental State Examination A preliminary study. Journal of Hong Kong College of Psychiatrists, 4 (Suppl 2), Critchley, M. (1953, reprinted 1966) The parietal lobes. New York: Hafner Publishing Company. Gnanalingham, K. K., Byrne, J., & Thornton, A. (1996). Clock-face drawing to differentiate Lewy body and Alzheimer type dementia syndromes. Lancet, 347, Lam, L. C. W., Chiu, H. F. K., Li, S. W., Chan, W. F., Chan, C. K. Y, Wong, M., & Ng, K. O. (1997). Screening for dementia A preliminary study on the validity of the Chinese version of the Blessed-Roth Dementia Scale. International Psychogeriatrics, 9, 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, Rouleau, I., Salmon, D. P., Butters, N., Kennedy. C, & McGuire, K. (1992). Qualitative and quantitative analyses of clock drawings in Alzheimer's and Hungtington's disease. Brain and Cognition, 18, Shulman, K. I., Gold, D. P., Cohen, C. A., & Zucchero, C. A. (1993). Clock-drawing and dementia in the community: A longitudinal study. International Journal of Geriatric Psychiatry, 8, Shulman, K. I., Shedletsky, R., & Silver, I. L. (1986). The challenge of time: Clock-drawing and cognitive function in the elderly. International Journal of Geriatric Psychiatry, 1, Sunderland, T., Hill, J. 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British Journal of Psychiatry, 152, Received November 7, 1997 Accepted May 28, 1998 Appendix Scoring Criteria for Clock-Drawing Test Score Criteria Example 0 Correct denotation of time with normal spacing 1 Slight impairment in spacing of lines or numbers 2 Noticeable impairment in line spacing (continued next page)

5 CLOCK DRAWING TEST IN DEMENTIA SCREENING P357 Score Criteria 3 Incorrect spacing between spokes (or numbers) with subsequent inappropriate denotation of time Appendix (continued) Scoring Criteria for Clock-Drawing Test Example Score Criteria A recognizable attempt to draw a clock face but with no clear denotation of time Example Obvious errors in correct time denotation (e.g., arms grossly misplaced, numbers drawn at wrong places) More obvious errors in time denotation (e.g., one arm omitted, circle the numbers or lines of clock face instead of drawing arms) Abnormal clock-face drawing with inaccurate time denotation (e.g., reversal of numbers, perseveration beyond twelve, misplaced numbers, drawing only to one side, omitting most numbers) Some evidence that a clock face is drawn Minimal evidence that a clock face is drawn 10 No reasonable or understandable attempt of drawing a clock face (exclude gross visual disturbance, hemiplegia, severe psychotic state rendering uncooperativeness)