Bedside assessment of cognitive heterogenety with clock drawing performance among clinical subtypes of schizophrenia — preliminary study

INTRODUCTION: Cognitive deficit is the enduring, persistent, and core feature of schizophrenia associated with increased risk of psychosocial disability. The cognitive deficit is highly prevalent, and variable according to the type of schizophrenia and course of illness. It is often overlooked by clinicians because of the complexity of assessment. The clock drawing test (CDT) is a brief, simple, and widely used cognitive screening instrument. AIM: To compare the level of cognitive impairment among subtypes of schizophrenia using CDT. MATERIALS AND METHODS: The CDT performance of institutionalized patients with schizophrenia of three clinical subtypes, Paranoid (n = 45), undifferentiated (n = 45), and disorganized (n = 45) was compared with age and sex-matched controls (n=45). The severity of symptoms in each group was assessed using Free drawn CDT, Positive and Negative Symptoms Scale (PANSS), and a Brief Psychiatric Rating Scale (BPRS) at the time of admission. The χ2 test and One-way ANOVA test with Bonferroni multiple comparison test were used to compare these groups. Pearson correlation coefficients were calculated to determine the bi-variate relationship among continuous variables including PANSS score, BPRS score, CDT Score, and Mini-Mental Status Examination (MMSE) Score among various comparison groups. RESULTS: The patients in the disorganized group (3.06 ± 2.27) performed more poorly than the paranoid group (6.06 ± 1.86), undifferentiated (4.60 ± 2.71), and the comparison group (8.68 ± 1.22), p 0.004. The CDT performance was negatively correlated with the PANSS score (r = -0.47, p 0.001) and BPRS score (r = -0.47, p 0.001) among three subtypes. The MMSE was highly correlated with CDT score among the disorganized group (r = 0.65, p 0.001) than the paranoid group (r = 0.43, p 0.05). CONCLUSION: Our findings suggest that the CDT test can be used at the bedside to distinguish between disorganized and paranoid types of schizophrenia. The disparity in CDT performance may be due to the different involvement of neural correlates among schizophrenia subtypes. Furthermore, CDT performance may be useful to clinicians in routine clinical practice in selecting appropriate pharmacological and psychosocial interventions.