Screening for dementia of the alzheimer type in the community: The utility of the clock drawing test

Abstract

This study reports the sensitivity and specificity of the Clock Drawing Test (CDT) for detecting dementia of the Alzheimer type in a community-dwelling sample of elderly subjects. Forty-two patients with clinically diagnosed Alzheimer's disease and 237 cognitively intact subjects were administered the CDT as part of an epidemiological study of aging and dementia. Three individual measures of clock drawing performance (quantitative score, qualitative score, and combined quantitative and qualitative score) were determined for each participant. When qualitative elements such as errors and strategies were incorporated into the CDT score, the sensitivity was 84% and the specificity was 72%. The findings suggest that a CDT score which evaluates qualitative and quantitative features provides reasonably good discrimination between normal elderly individuals and DAT patients. However, the CDT appears to have limited utility as a single screening instrument in the community. Instruments such as the Dementia Rating Scale (Mattis, 1976) provide better discrimination of DAT, indicating that functions such as memory and verbal fluency need to be assessed during screening.

Neuroanatomical correlates of error types on the Clock Drawing Test in Alzheimer's disease patients

“…Some studies suggested that “uneven number spacing” (Mendez item 5) corresponds to visuospatial difficulty or planning deficit, and that this relates to the parietal or frontal lobe, whereas in the present study, the association of errors in Mendez item 5 was found only with the frontal lobe.…”

“…In one error, the patients set the hands at 11:50 instead of 11:10, presumably affected by the direct auditory input of hearing “11” and “10” when instructed. This error is called a “stimulus‐bound response”, and this response is thought to occur as a consequence of frontal lobe dysfunction . In the other error, the patient set the minute hand to a completely different time (the hour hand was set to 11 in most cases).…”

Clock drawing test in mild and moderate dementia of the Alzheimer's type: a comparative and correlation study

“…The utility of different quantitative CDTs to detect change during the various stages of the dementing process needs further investigation and clarification. The consideration of qualitative aspects of performance as well may enhance clinical accuracy (Cahn et al, 1996).…”

Quality of life in cognitively impaired older adults

“…11 Visuospatial ability was evaluated using the quantitative and qualitative clock-drawing tests. 12 Verbal fluency was assessed using the letter fluency test and category fluency (animal naming) test. Processing speed was assessed using the Digit Symbol subtest of the Wechsler Adult Intelligence Scale-III.…”