Development of Scoring Criteria for the Clock Drawing Task in Alzheimer's Disease

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Abstract
Objective To investigate the reliability and validity of freehand clock drawings, a frequently used measure of constructional apraxia, in patients with Alzheimer's disease. Design Survey for the purpose of testing reliability and validity of a new scale. Setting Memory Disorder Clinic at a university‐affiliated hospital in the Upper Midwest. Patients Forty‐six patients were diagnosed with clinically probable dementia of the Alzheimer type after a dementia evaluation, and 26 normal elderly controls were research volunteers without a history of cognitive dysfunction. Measurements Neuropsychological tests, dementia‐related scales, and clock drawings rated by a new 20‐item Clock Drawing Interpretation Scale. Reliability measures, correlations, and clustering of items in the CDIS. Results The CDIS had inter‐rater reliability (r = .94), internal consistence (rtt = .95), and reproducibility over a 6‐month interval. CDIS scores were significantly correlated with two dementia‐related scales and all neuropsychological tests and had the highest correlations with other measures of constructional apraxia. All but four Alzheimer patients (91%) and none of the controls had CDIS scores of 18 or less. Conclusion Clinicians may reliably screen patients with Alzheimer's disease with the clock‐drawing task, a measure sensitive to deficits in constructional apraxia.