Executive dysfunctions in schizophrenia

Abstract

Studies suggest that executive functions in patients with schizophrenia are markedly impaired as compared with normal controls. Most previous studies employed tests of executive functions adopted from frontal lobe neuropsychological paradigms based on lesion studies. This study employed several more recently developed theory-driven tests of executive functions addressing the construct of the supervisory attentional system. We explore the pattern of executive function impairment using factor analysis and subsequently investigate the relationships between these executive function factors and the clinical features in a sample of chronic schizophrenic patients. A total of 51 patients with chronic schizophrenia were recruited. The Sustained Attention Response to Task (SART), Six Elements Test (SET) and Hayling Sentence Completion Test (HSC) were used to assess executive functions. Three factors were identified within the executive function tests: 1) The "semantic inhibition factor" comprised items in the HSC, 2) the "action/attention inhibition" factor comprised the SART commission error and the SET rule-breaking score and 3) the "output generation factor" comprised the SET raw score and the correct SART response. Significant relationships were found between these derived factors and clinical features after partialling out the confounding effect of age, education and illness duration. The three theory-based tests of executive function were shown to have good construct validity among the group of chronic schizophrenic patients.

Neurological soft signs as candidate endophenotypes for schizophrenia: A shooting star or a Northern star?

“…Moreover, Chan and Chen (2004b) demonstrated that significant relationships were found between specific executive function components and neurological soft signs. Specifically, motor coordination was correlated with attention inhibition component, verbal performance and visual memory; sensory integration was correlated with initiation component and verbal functioning; and disinhibition signs were associated with attention inhibition component.…”

“…Moreover, Chan et al (2004b) found that the disinhibition signs were associated with behavioural disinhibition task and blink rate in a group of 90 patients with chronic schizophrenia. The modest correspondence of the factor analytic data and conceptual models might be due to a number of methodological limitations.…”

Response Inhibition in Adults with Autism Spectrum Disorder Compared to Attention Deficit/Hyperactivity Disorder

“…Executive dysfunction is commonly seen following head injury (Stuss and Gow 1992) and also in a number of psychiatric (e.g. Chan et al 2004) and neurological disorders (e.g. Swanberg et al 2004) where the frontal lobes are implicated.…”

Alteraciones neurocognitivas en la esquizofrenia. Análisis factorial

“…Por ejemplo, Chan et al (2004), en 51 pacientes crónicos encontraron tres factores: uno de inhibición semántica, otro de inhibición de la atención/acción y otro de generación de la acción (iniciativa), así como una relación entre estos componentes y las características clínicas 23 . Estos autores también han encontrado alteraciones en componentes de la función ejecutiva en individuos con esquizofrenia crónica y en pacientes con un primer episodio, libres de medicación, como son la iniciativa, la atención sostenida, la flexibilidad al cambio, la planificación, la inhibición y la actualización 24 .…”