Executive function in first-episode schizophrenia: A three-year longitudinal study of an ecologically valid test

Department of Psychiatry, The University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong.
Schizophrenia Research (Impact Factor: 3.92). 12/2010; 126(1-3):87-92. DOI: 10.1016/j.schres.2010.11.023
Source: PubMed


Executive function impairment is a key cognitive deficit in schizophrenia. However, traditional neuropsychological tests of executive function may not be sensitive enough to capture the everyday dysexecutive problems experienced by patients. Additionally, existing literature has been inconsistent about longitudinal changes of executive functions in schizophrenia. The present study focuses on examining the longitudinal change of executive functions in schizophrenia using the Modified Six Elements Test (MSET) that was developed based on the Supervisory Attentional System model and shown to be sensitive to everyday dysexecutive problems. In the present study, MSET performance was assessed in 31 medication-naïve first-episode schizophrenic patients at four times over a period of three years, while the 31 normal controls were assessed once. Patients demonstrated impairment in MSET as compared to controls. Importantly, the MSET impairment persisted from the medication-naïve state to clinical stabilization and the three years following the first psychotic episode though patients improved in a conventional executive test (Modified Wisconsin Card Sorting Test). Performance was not related to intelligence, educational level, symptom changes, age-of-onset, or duration of untreated psychosis. Better MSET performance at medication-naïve state predicted improvement in negative and positive symptoms over the three-year period. These findings may suggest that MSET impairment is a primary deficit in schizophrenia that occurs early in the course of the illness and remains stable irrespective of clinical state for at least three years following the first episode of schizophrenia.

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Available from: Sherry K W Chan, Feb 27, 2014
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    • "Measuring performance of a cognitive construct using alternative tests can result in incongruent findings (Liu et al., 2011). The current study aimed to address this issue by implementing the MATRICS Consensus Cognitive Battery (MCCB), which was developed by the National Institute of Mental Health's (NIMH) Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS). "
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    ABSTRACT: While cognitive impairments are prevalent in first-episode psychosis, the course of these deficits is not fully understood. Most deficits appear to remain stable, however there is uncertainty regarding the trajectory of specific cognitive domains after illness onset. This study investigates the longitudinal course of cognitive deficits four years after a first-episode of psychosis and the relationship of performance with clinical course and response to treatment. Twenty three individuals with psychotic illness, matched with 21 healthy volunteers, were assessed using the MATRICS Consensus Cognitive Battery at illness onset and 4years later. We also investigated the relationship between cognitive deficits and quality of life and clinical indices. Verbal learning and two measures of processing speed had marked poorer trajectory over four years compared to the remaining cognitive domains. Processing speed performance was found to contribute to the cognitive deficits in psychosis. Poorer clinical outcome was associated with greater deficits at illness onset in reasoning and problem solving and social cognition. Cognitive deficits did not predict quality of life at follow-up, nor did diagnosis subtype differentiate cognitive performance. In conclusion, an initial psychotic episode may be associated with an additional cost on verbal learning and two measures of processing speed over a time spanning at least four years. Moreover, processing speed, which has been manipulated through intervention in previous studies, may represent a viable therapeutic target. Finally, cognition at illness onset may have a predictive capability of illness course.
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    • "There is no established consensus of which tests are best suited to assess executive functions, nor is there any single test that assesses all components of executive function. Thus, some criticism has been directed towards an inconsistently defined executive domain (Bozikas and Andreou, 2011) and longitudinal studies have shown ambiguous findings (Liu et al., 2011). Executive functioning is a multi-dimensional construct covering several subprocesses including, working memory, fluency, flexibility, inhibitory control and problem-solving. "
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    No preview · Article · Jun 2015
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    • "A person who cannot integrate information from gaze may get some troubles in abstract thinking [31,32]. Because visual searching seems to be influenced by a “top-down process” [14], patients with schizophrenia who have executive dysfunctions may have ineffective searching strategies when abstract thinking is required [33]. It is unclear what mechanism is underlying this relationship between defects in abstract thinking and abnormalities in oculomotor movement or visual searching behaviors. "
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    ABSTRACT: Effective integration of visual information is necessary to utilize abstract thinking, but patients with schizophrenia have slow eye movement and usually explore limited visual information. This study examines the relationship between abstract thinking ability and the pattern of eye gaze in patients with schizophrenia using a novel theme identification task. Twenty patients with schizophrenia and 22 healthy controls completed the theme identification task, in which subjects selected which word, out of a set of provided words, best described the theme of a picture. Eye gaze while performing the task was recorded by the eye tracker. Patients exhibited a significantly lower correct rate for theme identification and lesser fixation and saccade counts than controls. The correct rate was significantly correlated with the fixation count in patients, but not in controls. Patients with schizophrenia showed impaired abstract thinking and decreased quality of gaze, which were positively associated with each other. Theme identification and eye gaze appear to be useful as tools for the objective measurement of abstract thinking in patients with schizophrenia.
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