Fractionating the executive function in schizophrenia: does it still hold true for medication-naive sample?

Abstract

BACKGROUND: Preliminary studies suggest that the phenomenon of fractionation of executive functions takes places in patients with chronic schizophrenia. However, we do not get much evidence to support this claim in first-onset medication-naı¨ve sample. In this study, we attempted to examine whether this phenomenon still holds true in medication-naı¨ve schizophrenia. METHODS: A sample of 78 medicatio- naı¨ve patients with schizophrenia and another sample of 60 healthy controls were recruited for the present study. All subjects completed a comprehensive set of executive function tests assessing initiation, sustained attention, online updating, switching, attention allocation, inhibition, and background cognition. RESULTS: 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 component. Moreover, the majority of executive function components did not correlate with intellectual functioning and memory impairment in a sub-group of patients without intellectual impairment. CONCLUSIONS: These findings suggest that the phenomenon of fractionation of executive functions still holds true in the medication-nay¨ve sample. In particular, these patients show a specific pattern of executive dysfunction compared to healthy controls and patients with an established illness. This differential breakdown in executive function components is unlikely to be an artifact of general intellectual decline or memory impairment in schizophrenia.