Elsevier

Schizophrenia Research

Volume 80, Issues 2–3, 15 December 2005, Pages 213-225
Schizophrenia Research

Biosocial pathways to functional outcome in schizophrenia

https://doi.org/10.1016/j.schres.2005.07.008Get rights and content

Abstract

Biosocial models are preeminent in the study of schizophrenia, yet there has been little empirical testing of these models.

Objective

This study provided the first test of a biosocial causal model of functional outcome in schizophrenia, using neurocognition, social cognition, social competence and social support as predictors of both global and specific domains of functional outcome.

Method

The design used baseline variables to predict both concurrent functional status and prospective 12-month functional outcome. Subjects were recruited upon admission to outpatient community-based psychosocial rehabilitation programs shown in previous studies to be effective in improving functional outcomes. 139 individuals diagnosed with schizophrenia or schizoaffective disorder participated in the study; 100 participants completed the 12-month assessments. Face-to-face interviews assessed neurocognitive functioning (with five neuropsychological measures), social cognition (as perception of emotion), social competence, social support, and functional outcome which consisted of items covering the domains of social, independent living, and work functioning.

Results

Path analysis modeling showed that the proposed biosocial models had strong fit with the data, for both concurrent and 12-month global functional outcomes, with fit indices ranging from .95 to .98. The model explained 21% of the variance in concurrent global functional outcome, and 14% of the variance in 12-month prospective outcome.

Conclusions

The support for this model was strong, and it has implications for understanding the causal factors related to functional outcome, as well as for intervention strategies for improving functional outcomes in schizophrenia.

Section snippets

Neurocognition

A growing body of research has shown that neurocognitive variables are related to functional outcomes (Green, 1996, Green et al., 2000). Meta-analyses have indicated that secondary and immediate verbal memory, executive functioning, and sustained attention may each be separately predictive of functional outcome in schizophrenia (Green et al., 2000). Composite neurocognitive measures may reveal larger relationships with functional outcomes than do individual neurocognitive constructs (Green et

Social cognition

Social cognition, defined as the “cognitive processes involved in how [people] think about themselves, other people, social situations, and interactions” (Penn et al., 1997a, p. 114), is differentiated from, but not orthogonal to, nonsocial cognition. While both are impaired in schizophrenia, the stimuli in social cognition studies tend to be personally relevant, changeable, interactive, and complex compared to the stimuli in nonsocial cognition studies, which use words, tones, numbers, and

Social competence

Social skills may be defined as a “specific set of abilities, including cognition, verbal, and nonverbal behaviors that are needed for effective interpersonal performance” (Mueser et al., 1998). There is evidence that neurocognitive capacity is related to social skill acquisition (Green and Nuechterlein, 1999). Competence in social skill may also mediate the relationship between ability to perceive affect and functional outcome (Mueser et al., 1996). Studies have found that persons with

Social support

Social support has been defined as the “…caring and sustenance provided by the social environment”(Kendler, 1997, p. 2) and ‘‘…he emotional support, advice, guidance, and appraisal, as well as the material aid and services, that people obtain from their social relationships” (Ell, 1984, p. 134). Perceived social support has long been considered important to prevention of relapse and to rehabilitation, consistent with stress-vulnerability models of schizophrenia which posit that social support

Functional outcome

While psychosocial outcome in schizophrenia may be considered in several domains, such as clinical, subjective, and functional (Brekke and Long, 2000), we focus on the functional outcomes of work, independent living, and social functioning of individuals living in the community. It has been argued that multiple domains of outcome in schizophrenia are linked but separate (Brekke and Long, 2000, Strauss and Carpenter, 1972) and that they could have distinct biosocial pathways (Brekke et al., 1997c

Method

Participants in this study were recruited as they were admitted to four community-based psychosocial rehabilitation programs in urban Los Angeles. The programs were part of a county mandated mental health initiative (Young et al., 1998) and were selected on the basis of data showing that they were comprehensive service environments that yielded significant improvements in functional outcomes over time (Bae et al., 2004, Brekke et al., 1997b, Brekke et al., 2003). Participants were assessed at

Subjects

The sample consisted of 139 individuals diagnosed with schizophrenia or schizoaffective disorder who completed baseline test batteries including neurocognition, social cognition, and psychosocial functioning. Subjects were recruited and followed prospectively for 12 months from between 1996–2000. Fifty-six percent of the subjects came from site 1, 16% from site 2, 16% from site 3, and 12% from site 4. Diagnoses were determined using clinical records, a DSM-IV checklist, and collateral reports

Measures

All psychosocial variables came from data gathered in face-to-face interviews conducted at a place of the subject’s choosing, typically at a program site or their residence. The interviewers were masters-level clinicians trained using a protocol described in detail (Brekke et al., 1993). They were trained on the Brief Psychiatric Rating Scale (Lukoff et al., 1986) using a protocol described in Ventura et al. (1995). The neurocognitive and social cognition data came from laboratory-based

Psychosocial measures

The measure of social competence is a subscale of the Community Adjustment Form (CAF) (Test et al., 1991). The CAF uses trained interviewers to gather behavioral event data from 17 domains of community functioning such as living situation, work and social functioning, family involvement, and medication use. It includes a 10-item scale of prosocial behaviors rated by the interviewer as an indicator of social competence. The behaviors reflect the four components of social skill described by

Social cognition measures

Affect perception was measured by the following three scales from which the simple sum of correct responses was derived: 1) the Facial Emotion Identification Test (Kerr and Neale, 1993), 2) the Voice Emotion Identification Test (Kerr and Neale, 1993), and 3) the Videotape Affect Perception Test (Bellack et al., 1996). These tests and the procedures for administering them are fully described in Kee et al. (1998). All three require the subject to select one of six basic emotions (i.e., happy,

Neurocognitive measures

The neurocognitive measure in this study is a composite created to reflect verbal fluency, immediate memory, secondary memory, sustained attention, and mental flexibility. It was derived from five tests by summing the standardized scores. The five tests were the Controlled Oral Word Association Test (Lezak, 1995), the Digit Span Distractibility Test (Oltmanns and Neale, 1975), the California Verbal Learning Test (Delis et al., 1987), the Degraded-Stimulus Continuous Performance Test (

Data analysis

Path analysis is a method to test the theory-driven causal relationships of constructs in a proposed theoretical model. It can be used in non-experimental contexts with statistical associations, and when combined with theory it is used to test causal structures among variables. It has been used in schizophrenia research to specify paths to relapse (Nuechterlein et al., 1992), as well as to understand the influence of expressed emotion on social adjustment (King and Dixon, 1996). Since it is

Results

The means and standard deviations of the variables in the path analysis are shown in Table 1. Zero-order correlations of the manifest variables in the path analysis are shown in Table 2. When symptom levels were entered as a covariate into all of the models tested, there was no change in most of the parameters estimated, and in other instances it was negligible; therefore, the results are presented without including the symptom variable in the models.

Model fit

We used the following six well-recognized fit indices: the χ2 test; the Normed Fit Index (NFI), where values greater than .9 are considered good; the Standardized Root Mean Square Residual (SRMR) where a lower score indicates better fit; Adjusted Goodness-of-Fit Index (AGFI) where above .9 is good fit; the Root Mean Square Error of Approximation (RMSEA) where values of less than .08 are considered good; the Expected Cross-Validation Index (ECVI) where a small ECVI value indicates the model is

Predictor model

The final predictor model is shown in Fig. 2. The proposed path from neurocognition to social competence was not statistically significant (b = .036, t = .35, p > .10), therefore it was eliminated from all further model testing. All of the remaining paths were statistically significant. The increment to χ2 test was not significant between the initial and final predictor model. From Table 3 it can be seen that the fit indices for the final predictor model were strong. These results support the

Global outcome models

Based on each of the fit indices (see Table 3), the global model of concurrent functional status fit the data well. All of the direct effect parameter estimates were in the expected direction and five of seven path estimates were statistically significant. The model explained 21% of the variance in global functional outcome. The direct path from neurocognition to functional outcome was not significant, while the path from social support to outcome was significant at a trend level (p < .07). Since

Models of distinct outcome domains

Concurrent and prospective models predicting the three distinct outcome domains of social, work, and independent living also fit the data very well. In terms of concurrent functional variables, the model explained 19% of the variation in social functioning, 15% of the variation in work functioning, and 11% of the variation in independent living. Considering 12-month functional outcomes, the model explained 10% of the variance in social, work and independent living outcomes. The model fit

Model misspecification

The fit of a global concurrent outcome model with the variables in miss-specified order (not simply reversed) was tested. χ2 was statistically significant (p < .001), the NFI was .81, the AGFI was .76, and the SRMR was > .09. These indices represent a notable degradation in model fit from the theoretically specified model and reinforce the importance of the specified ordering of the variables in this model.

Direct and indirect effects

The direct effects are noted in Fig. 2a–d. The indirect effects are computed by summing the path coefficient products for each indirect path from predictor to outcome. The total effect is figured by adding direct plus indirect effects. Table 4, Table 5 present direct, indirect, and total effects in each of the concurrent and prospective models. The pattern and magnitude of direct and indirect effects was very similar for the concurrent and prospective models with two exceptions. The indirect

Discussion

We tested a model that included neurocognition, social cognition, social competence, and social support as predictors of global functional outcome, and also as predictors of the separate outcome domains of work, independent living, and social functioning. The results indicate a fairly consistent pattern across outcome domains and across time. First, the statistically significant total effects of neurocognition on functional outcome were entirely mediated through other variables in each of the

Acknowledgement

This research was supported by grants MH53282 and MH01628 from the National Institute of Mental Health awarded to the first author, and by the Department of Veterans Affair VISN 22 Mental Illness Research Education and Clinical Center.

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