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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    • "The positive symptoms of schizophrenia specifically hallucinations and delusions -account for a negligible proportion of the variance in such functional outcomes in clinically stable samples (Ventura et al., 2009). In contrast, there have been consistent reports of moderate associations between greater negative symptoms, characterised by motivational or interpersonal impairments, with poorer functional outcomes (Ventura et al., 2009). However, these associations are small to moderate in magnitude highlighting the need for novel theoretic al and empirical perspectives to generate a better understanding of negative symptoms and functioning. "

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    • "Addington et al., 1991; Liddle and Morris, 1991; Berman et al., 1997; Voruganti et al., 1997; Basso et al., 1998; O'Leary et al., 2000; Moritz et al., 2001; Brazo et al., 2002; Sanfilipo et al., 2002; Ihara et al., 2003; Bozikas et al., 2004; Heydebrand et al., 2004), but not all (e.g. Himelhoch et al., 1996; Collins et al., 1997; Daban et al., 2002; Minzenberg et al., 2003; Lucas et al., 2004; Rund et al., 2004), while meta-analyses have generally found small to moderate correlations between negative and cognitive symptoms (Nieuwenstein et al., 2001; Dibben et al., 2009; Dominguez Mde et al., 2009; Ventura et al., 2009). These two domains have been described as separable although not conceptually independent, and models in which negative symptoms and cognitive dysfunction may have related etiologies, overlapping definitions or measurements, or shared correlations with distal outcomes have been proposed (Harvey et al., 2006). "
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    ABSTRACT: Previous studies have generally found a relationship between negative and cognitive symptoms in schizophrenia. The present study investigated the relationship between the 5 PANSS factors of a recent consensus model developed by NIMH researchers, and cognitive performance as assessed with the MATRICS Consensus Cognitive Battery (MCCB) in 80 patients with schizophrenia using correlation and regression analyses. The PANSS Cognitive factor showed a small to moderate significant association with MCCB Speed of processing, Working memory, Verbal learning, the Neurocognitive composite score, and the Overall composite score. Notably, however, no relationship was found between the PANSS Negative factor and any of the MCCB scores. The Positive, Excited and Depressed factors also did not show associations with the MCCB. These results highlight the need for refined assessment instruments and support the relative independence of cognition from other domains of psychopathology, including negative symptoms, in patients with schizophrenia.
    Full-text · Article · Oct 2015
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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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