Elsevier

Biological Psychiatry

Volume 63, Issue 5, 1 March 2008, Pages 505-511
Biological Psychiatry

Original Article
Predicting Schizophrenia Patients’ Real-World Behavior with Specific Neuropsychological and Functional Capacity Measures

https://doi.org/10.1016/j.biopsych.2007.05.022Get rights and content

Background

Significant neuropsychological (NP) and functional deficits are found in most schizophrenia patients. Previous studies have left questions as to whether global NP impairment or discrete domains affect functional outcomes, and none have addressed distinctions within and between ability and performance domains. This study examined the different predictive relationships between NP domains, functional competence, social competence, symptoms, and real-world behavior in domains of work skills, interpersonal relationships, and community activities.

Methods

Two hundred twenty-two schizophrenic outpatients were tested with an NP battery and performance-based measures of functional and social competence and rated for positive, negative, and depressive symptoms. Case managers generated ratings of three functional disability domains.

Results

Four cognitive factors were derived from factor analysis. Path analyses revealed both direct and mediated effects of NP on real-world outcomes. All NP domains predicted functional competence, but only processing speed and attention/working memory predicted social competence. Both competence measures mediated the effects of NP on community activities and work skills, but only social competence predicted interpersonal behaviors. The attention/working memory domain was directly related to work skills, executive functions had a direct effect on interpersonal behaviors, and processing speed had direct effects on all three real-world behaviors. Symptoms were directly related to outcomes, with fewer relationships with competence.

Conclusions

Differential predictors of functional competence and performance were found from discrete NP domains. Separating competence and performance provides a more precise perspective on correlates of disability. Changes in specific NP or functional skills might improve specific outcomes, rather than promoting global functional improvement.

Section snippets

Subjects

Subjects were older schizophrenia outpatients enrolled in a longitudinal study of the course of cognitive and functional status. Seventy-eight subjects in this study were part of our previously published report (9). Exclusion criteria consisted of a primary DSM-IV (13) Axis I diagnosis other than schizophrenia or schizoaffective disorder, Mini-Mental Status Examination score below 18, Wide Range Achievement Test (WRAT) reading grade equivalent of grade 6 or less, or any diagnoses in a patient’s

Results

In these analyses, 222 patients were assessed with all instruments and had case manager reports on the SLOF. Demographic and performance data are presented in Table 1.

Four factors emerged from the analysis and were named based on the theoretical constructs of the tests that had the highest loading. See Table 2 for the rotated factor loadings.

All three models of the outcomes had excellent fit, with the final model superior to the independence model (Table 3). In these models, there were no

Discussion

Cognitive impairment is a core feature of schizophrenia, which is associated with the functional disabilities that have proven resistant to treatment. Similar to our previous findings (9), with a smaller, but overlapping sample, this study reveals complex relationships between cognitive abilities and functional outcomes. By modeling different behaviors (work skills, interpersonal, community activities), the same cognitive skill may relate to performance directly or through its relationship with

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