Symptoms as mediators of the relationship between neurocognition and functional outcome in schizophrenia: A meta-analysis

UCLA Department of Psychiatry and Biobehavioral Sciences, Los Angeles, CA 90095-6968, USA.
Schizophrenia Research (Impact Factor: 3.92). 08/2009; 113(2-3):189-99. DOI: 10.1016/j.schres.2009.03.035
Source: PubMed


Neurocognitive functioning in schizophrenia has received considerable attention because of its robust prediction of functional outcome. Psychiatric symptoms, in particular negative symptoms, have also been shown to predict functional outcome, but have garnered much less attention. The high degree of intercorrelation among all of these variables leaves unclear whether neurocognition has a direct effect on functional outcome or whether that relationship to functional outcome is partially mediated by symptoms.
A meta-analysis of 73 published English language studies (total n=6519) was conducted to determine the magnitude of the relationship between neurocognition and symptoms, and between symptoms and functional outcome. A model was tested in which symptoms mediate the relationship between neurocognition and functional outcome. Functional outcome involved measures of social relationships, school and work functioning, and laboratory assessments of social skill.
Although negative symptoms were found to be significantly related to neurocognitive functioning (p<.01) positive symptoms were not (p=.97). The relationship was moderate for negative symptoms (r=-.24, n=4757, 53 studies), but positive symptoms were not at all related to neurocogniton (r=.00, n=1297, 25 studies). Negative symptoms were significantly correlated with functional outcome (r=-.42, p<.01), and again the correlation was higher than for positive symptoms (r=-.03, p=.55). Furthermore, our findings support a model in which negative symptoms significantly mediate the relationship between neurocognition and functional outcome (Sobel test p<.01).
Although neurocognition and negative symptoms are both predictors of functional outcome, negative symptoms might at least partially mediate the relationship between neurocognition and outcome.

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    • "Cognitive deficits in schizophrenia are related to functional outcomes, as shown in both crosssectional (Fett et al., 2011, Green et al., 2000, Ventura et al., 2009) and longitudinal studies (Allott et al., 2011, Green et al., 2004, Ventura et al., 2011). However, some studies have failed to confirm this relationship (e.g. "
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    ABSTRACT: The purpose of this study was to study neurocognitive performance as a predictor of outcomes in midlife schizophrenia. There is a lack of studies with unselected samples and a long follow-up. The study is based on the prospective, unselected population-based Northern Finland Birth Cohort 1966. The study includes 43 individuals with schizophrenia and 73 controls, whose neurocognitive performance was assessed twice, at 34 and 43 years. At both time points we used identical neurocognitive tests to assess verbal and visual memory and executive functions. Our main aim was to analyse neurocognitive performance at 34 years as a predictor of clinical, vocational and global outcomes at 43 years. Additionally, the analysis addressed cross-sectional associations between cognitive performance and clinical, vocational and global measures at 43 years. The assessment of outcomes was performed in the schizophrenia group only. In the longitudinal analysis poorer visual memory predicted poorer vocational outcome and poorer long-term verbal memory predicted poorer global outcome. In the cross-sectional analysis poorer visual memory and lower composite score of neurocognition associated with poorer global outcome. No individual neurocognitive test or the composite score of these predicted remission. These data indicate that neurocognition, especially memory function, is an important determinant of long-term functional outcome in midlife schizophrenia.
    Schizophrenia Research: Cognition 08/2015; 2(3). DOI:10.1016/j.scog.2015.07.001
    • "Psychiatry Research (2015), psychres.2015.07.022i negative symptoms (Ventura et al., 2009; Lin et al., 2013). The indirect effect is also demonstrated in longitudinal studies, which have suggested that NC underlies, and is causally primary to SC, motivation and functional outcome (Nakagami et al., 2010; Hoe et al., 2012). "
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    ABSTRACT: Understanding the complex relationship among determinants of real-world functioning in schizophrenia patients in remission is important in planning recovery-oriented interventions. We explored two path-analytical models of functioning in schizophrenia. 170 Schizophrenia patients remitted from positive symptoms underwent fairly comprehensive assessments of cognition - neurocognition (NC) and social cognition (SC), residual symptoms - insight, motivation and other negative symptoms, and socio-occupational functioning. We explored (a) a cascading model, where NC predicted functional outcome through its effects on other determinants and (b) a combined model, incorporating additional direct paths from each of the determinants. The combined model, and not the cascading model demonstrated a good fit. Post-hoc trimming of the combined model by elimination of non-significant paths maintained the goodness-of-fit and was retained as the final model. In addition to the direct paths, this final model demonstrated that (a) NC influenced functioning through SC and insight and (b) SC influenced functioning through motivation and negative symptoms. This suggests that NC and SC may influence functional outcome directly, as well as indirectly, via specific impact on insight, and motivation and negative symptoms respectively. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    07/2015; 229(1-2). DOI:10.1016/j.psychres.2015.07.022
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    • "Following the indication of the international Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) consensus in which each domain has to be composed by two different tests at least (Nuechterlein et al., 2008), we conduct exploratory analyses of composite scores to elucidate the mediation model of the relationship between a wide range of welldefined neurocognitive and social cognitive measures (Pinkham et al., 2013) and daily functioning (Leifker et al., 2011) in a sample of stable outpatients with schizophrenia. We studied a sample of predominant negative symptoms because they have shown to be more consistently associated with functional outcome than positive symptoms, but have garnered much less attention (Ventura et al., 2009). Specifically, we examined (1) whether the social cognitive performance uniquely accounts for incremental variance in daily functioning, independently of neurocognitive performance and psychiatric symptom severity, and (2) whether social cognitive performance mediates the relationship between neurocognitive performance and daily functioning. "
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    ABSTRACT: While the role of impaired neurocognition in accounting for functional outcome in schizophrenia is generally established, the influence of social cognition on this relationship is far from clear. This study aims to explore in depth the nature of the relationship between neurocognition, social cognition and daily functioning in people with schizophrenia. Twenty-one individuals diagnosed with schizophrenia and 15 controls completed the assessment of symptom severity, neuropsychological status, social cognition (Theory of Mind and affect processing) and other functional measures. A statistical mediation model based on hierarchical regression analyses was used to establish the mediation path with significant variables. Social cognition played a mediating role between neurocognition and functioning, accounting for significant trends in incremental variance in specific functional indexes (interpersonal behavior and employment/occupation). Consequently, this study adds to the evidence underlining the importance of targeting not only social cognitive or neurocognitive functions but to combine both interventions to reveal the best daily functioning results in schizophrenia patients.
    Psychiatry Research 02/2015; 225(3):374-380. DOI:10.1016/j.psychres.2014.12.011 · 2.47 Impact Factor
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