Comparison of a clock drawing test in elderly schizophrenia and Alzheimer's disease patients: A preliminary study

The objective of this study was to compare between the quantitative and qua litative aspects of a clock drawing test in elderly schizophrenic and Alzhe imers disease (AD) patients. Three independent raters performed a retrospec tive analysis of the clock drawing item from the Cambridge Cognitive Examin ation (CAMCOG), in long-term open wards of a public psychiatric hospital an d an outpatient psychogeriatric clinic. The study group comprised 21 elderl y schizophrenic patients ('graduates') and 21 AD patients matched for gende r and education, and cognitive impairment confirmed by a Folstein mini-ment al state examination (MMSE) score of 18-23. The Clock Drawing Interpretation Scale (CDIS), was the measure used. Schizo phrenic patients were significantly younger than AD patients (63.5 versus 8 1.3 years, p < 0.0001), however, similar concerning gender, education, MMSE and CAMCOG scores. CDIS scores were not correlated with age in either grou p. Inter-rater reliability was high (range 0.84-0.97). No significant diffe rences between patient groups were found in mean CDIS total scores. A CDIS specific item analysis revealed that schizophrenic patients were significan tly less impaired than AD patients on three out of 20 items: Number 7 (most symbols are aligned in a clockwise or a rightward direction), Number 8 (at l symbols are totally within a closure figure), and Number 13 (numbers do n ot go beyond 12). Although schizophrenic patients and AD patients had simil ar total scores nn the clock drawing test, they differed on specific test i tems related patients and AD patients had similar total scores on the clock drawing test, they differed on specific test items related to spatial/plan ning deficit and perseveration. Copyright (C) 2000 John Wiley & Sons, Ltd.