Investigation into cognitive function in first episode psychosis and chronic schizophrenia patients. An investigation into cognitive deficits associated with first episode psychosis and chronic schizophrenia patients in South Asian and Caucasian populations as assessed by the Cambridge Neuropsychological Test Automated Battery (CANTAB).

Abstract

Rationale Cognitive deficits are now recognised as a major symptom of schizophrenia with a number of studies reporting profound deficits in cognitive function in both chronic and first episode patients. Recent advances in cognitive remediation therapy have provided the opportunity for patients to improve their cognitive function and therefore improve their functional outcome. Aim The aim of the present study was to investigate cognitive deficits using the Cambridge Neuropsychological Test Automated Battery (CANTAB®) in first episode psychosis and chronic schizophrenia patients. In the first episode population the effect of ethnicity on cognition was also examined. In the chronic schizophrenia study comparisons between severity of deficits with first episode psychosis patients were also made. The effects of cognitive remediation therapy were also examined in a sample of first episode patients. Methods A total of 35 patients and 30 healthy controls were recruited into the first episode study, 17 patients and 17 controls into the chronic schizophrenia study and 11 patients into the cognitive remediation study. The first episode psychosis patients were recruited from the Bradford and Airedale Early Intervention Service and the chronic patients from the Leeds Partnership NHS Foundation Trust. The control subjects were matched as closely as possible in terms of intelligence and demographics to the patient groups. The Wechsler Test of Adult Reading (WTAR) was used to estimate subjects pre-morbid IQ. The severity of symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). All subjects who took part in the study completed a comprehensive battery of neuropsychological tests from the CANTAB®. Patients in the cognitive remediation study participated in group therapy sessions using X-cog®. Results There were no significant differences found between There were no significant differences found between patients and controls in relation to intelligence or demographics in all studies. The effect of ethnicity was shown to be not significant in the first episode study. Results show that patients performed significantly worse than controls across all iv cognitive domains tested in all studies. A correlation between negative symptoms and executive function was found in both first episode and chronic schizophrenia patients. Comparisons between first episode psychosis and chronic schizophrenia patients in cognition showed no significant differences, however significant differences were found in levels of negative symptoms and age between the two groups with chronic patients scoring higher on negative symptoms and being older. In the cognitive remediation study a significant improvement was observed in patients in the domain of executive function and a reduction in negative symptoms following completion of the intervention. Conclusion First episode and chronic schizophrenia patients display significant cognitive deficits across all domains when tested using the CANTAB®. Some of these deficits appear to be independent of the length of the illness but dependent on negative symptoms. This study demonstrates that cognitive deficits exist across all patient groups regardless of age, gender, pre-morbid IQ, years in education and ethnicity. Cognitive remediation therapy has also been shown to be effective in improving cognitive functioning in patients.