Clock drawing test in elderly schizophrenia patients

Objective. Clock drawing has been studied in Alzheimer's disease but not in elderly schizophrenics. We examined clock drawing ability in elderly schizophrenia patients and sought possible correlations with demographic, clinical and cognitive variables. Design. Retrospective analysis of the clock drawing item from the Cambridge Cognitive Examination (CAMCOG) presented to three independent raters. Setting. Long-stay 'open' departments of a public psychiatric hospital in Israel. Patients, Thirty-one physically well psychiatric inpatients suffering from schizophrenia (DSM-III-R, APA), between ages 60 and 76 years. Measures. The Clock Drawing Interpretation Scale (CDIS). Results. The mean CDIS score was 14.4 (out of 20), and 61-84% of patients scored beneath the normal range (> 18). Interrater reliability was high (0.91-0.96). A moderate but significant correlation was found between CDIS and duration of illness as well as total scores on the Manchester Scale, the CAMCOG and the Mini-Mental State Examination, but not with the other variables studied. Conclusions. Clock drawing skills of a significant portion of long-term institutionalized elderly schizophrenics are impaired. When this test is used as a screening device for Alzheimer's disease in these patients, the results should be interpreted cautiously. Clock drawing abilities in these patients seem to be related to cognitive and non-cognitive (psychiatric state) factors, as well as to illness duration.