Elsevier

Acta Psychologica

Volume 115, Issues 2–3, February–March 2004, Pages 255-269
Acta Psychologica

Using saccade tasks as a tool to analyze executive dysfunctions in schizophrenia

https://doi.org/10.1016/j.actpsy.2003.12.009Get rights and content

Abstract

Executive dysfunctions can be frequently observed in schizophrenia. They are more persistent than psychotic symptoms and are assumed to contribute to a variety of clinical signs of the disease. However, the cognitive mechanisms underlying dysexecutive behaviors are not yet understood. The aim of this article is to demonstrate how saccade tasks can be used to analyze the mechanisms involved in the dysexecutive syndrome of schizophrenic patients. There are numerous reports showing that schizophrenic patients make many unwanted reflexive saccades in the antisaccade task. These errors are usually explained by an impairment of a distinct inhibitory mechanism. However, unwanted reflexive saccades may also be secondary to a more fundamental deficit in activating goal-directed behavior. Recent theoretical and empirical approaches to this issue are reviewed and discussed. An integrative view of deficits in inhibition, goal-directed behavior, and working memory in schizophrenic patients is proposed.

Introduction

Executive functions refer to the flexible control of cognition and action. Impairments of these functions appear to be a central characteristic of the cognitive dysfunctions associated with schizophrenia. However, we still do not know much about the processes that lead to dysexecutive symptoms in everyday life of schizophrenic patients, or to their poor performance commonly found in so-called frontal lobe tests. With the present article we intend to illustrate why it is interesting and promising to use saccade tasks in the analysis of executive deficits in schizophrenia. The focus of the discussion will be put on the putative mechanisms underlying impaired inhibitory control.

Section snippets

Cognitive dysfunction in schizophrenia

Alterations of cognition have been conceived as core features of schizophrenia since the first definitions of the disease by Kraepelin (1899) and Bleuler (1911). Modern neuropsychological research has shown that schizophrenic patients are sometimes severely impaired in a variety of cognitive functions, such as attention (Cornblatt & Keilp, 1994), learning and memory (Saykin et al., 1991), and executive control (Evans, Chua, McKenna, & Wilson, 1997; for reviews see Heinrichs & Zakzanis, 1998;

Specifying components of executive dysfunction in schizophrenic patients

Research on executive dysfunction is of particular interest in schizophrenia because a causal relationship is assumed between these dysfunctions and clinical symptoms of schizophrenia (Frith, 1992). However, results of empirical studies are not unequivocally supportive of the assumed relationship (Elliott & Sahakian, 1995). Inconsistent findings may result from methodological flaws in some of these studies, which correlated neuropsychological deficits with psychotic symptoms. One important

Conclusions

Executive dysfunctions appear to be a major characteristic of schizophrenia. They show up in a number of clinical symptoms and have frequently been documented as poor performance in standard neuropsychological tests. However, the cognitive mechanisms underlying disorganized, inflexible or disinhibited behaviors remain unclear. Saccade tasks may provide the means to get improved insights into some of these mechanisms. They address a relatively simple response system, which is particularly useful

Acknowledgments

This work was supported by grant Ka 815 4-1 from the Deutsche Forschungsgemeinschaft (DFG).

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