Background: There has been a growing need for a cognitive assessment tool that can be used for older adults with schizophrenia in clinical settings. The clock-drawing test (CDT) is a brief cognitive test that covers a wide range of cognitive function. Although it is widely used to assess patients with dementia, limited data are available on its usefulness in older patients with schizophrenia. Thus, we investigated the psychometric properties of the CDT and their relationship with life functions to examine the test's usefulness for assessing cognitive function in older adults with schizophrenia. Methods: Seventy-three older adults with chronic schizophrenia who had been hospitalized for over 1year participated in the study. We adopted the executive clock-drawing task for administration and scoring of the CDT, which consists of free-drawn and copy conditions. The Mini-Mental State Examination and the Brief Assessment of Cognition in Schizophrenia were administered. Symptom severity and life functions were assessed with the Positive and Negative Syndrome Scale and the Life Skills Profile, respectively. Results: Both free-drawn and copy scores significantly correlated with the Mini-Mental State Examination score and the Brief Assessment of Cognition in Schizophrenia composite score. These scores also significantly correlated with symptom severity and length of current hospitalization. Stepwise regression analysis showed that only the copy score, together with symptom severity, predicted the Life Skills Profile score. Conclusions: The CDT can assess cognitive function in older adults with schizophrenia. Moreover, CDT performance is associated with life functions independent from other clinical variables. These results suggest that the CDT is a useful cognitive assessment tool for this population.
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