In recent decade, deficits in the mechanism of Supervisory Attentional System (SAS) have become increasingly influential in explaining the nature of dysexecutive syndrome experienced by schizophrenic patients. The SAS model is characterized by having a detailed sub-classification of specific executive function components, among which semantic inhibition has been investigated using the Hayling Sentence Completion Test (HSCT). Several studies thus far have indicated that schizophrenic patients show impairment in HSCT performance. However, HSCT data concerning first-episode patients is still scarce. Besides, as previous HSCT studies were all cross-sectional in nature, they were not able to assess changes in HSCT performance over time. In order to address the paucity of knowledge about the longitudinal trajectories and correlates of semantic inhibition deficits in early schizophrenia, this paper reports a three-year prospective study of HSCT performance in medication-naïve, first-episode patients with schizophrenia-spectrum disorders. HSCT performance was assessed in 34 patients at four times over a period of three years, while the 34 healthy controls were assessed once. We found that medication-naïve patients demonstrated impairment in the inhibition condition in HSCT as compared to controls, but not in the initiation condition. Such HSCT impairment gradually improved in the three years following the first psychotic episode; however, HSCT performance did not predict improvement in negative or positive symptoms over the three-year period. The present findings suggest that semantic inhibition impairment is a specific deficit in schizophrenia that may require early intervention efforts, with the goal of facilitating more successful verbal communication and thereby better interpersonal functioning.
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