Specific executive dysfunction in patients with first-episode medication-naïve schizophrenia

Abstract

Many studies have shown that schizophrenia is associated with a wide range of cognitive impairments. Empirical findings suggest that patients with schizophrenia suffer from a "dysexecutive syndrome". However, the extent to which a general decline in neuropsychological function accounts for symptoms of executive dysfunction in schizophrenia is not clear. In this study, we examined further the nature and pattern of executive function in a sample of medication-naïve patients experiencing a first-episode of schizophrenia with a set of tests capturing the specific components of executive function. We also compared the performance of this clinical group with healthy controls. A total of 78 medication-naïve patients with first episode schizophrenia were recruited from the Early Assessment Service for Young People with Psychosis (EASY). Another 60 healthy controls were recruited for comparison. All subjects participated in a comprehensive set of executive function tests assessing initiation, sustained attention, online updating, switching, attention allocation, inhibition, and non-executive function. The executive function of patients with first-episode schizophrenia was found to be compromised relative to healthy controls. However, unlike patients with established schizophrenia, first episode patients exhibited only a limited deficit in sustained attention. Moreover, the majority of executive function deficits did not correlate with intellectual functioning and memory impairment in a sub-group of first episode patients without intellectual impairment. These findings suggest that first-episode patients exhibit a specific pattern of executive dysfunction compared to healthy controls and patients with an established illness. This differential breakdown of executive function components is unlikely to be an artefact of general intellectual decline or memory impairment in schizophrenia.