Objectives: There is general agreement that cognitive impairment, a core feature of schizophrenia, has a key influence on functional outcome in schizophrenia. The authors tested the hypotheses that specific types of cognitive function in patients with schizophrenia would be associated with social function, particularly work status. In addition, we investigated the relation between cognitive function and quality of life (QoL) in patients with schizophrenia.
Study 1: Work function and cognitive assessment data were collected in 59 treatment-resistant patients with schizophrenia or schizoaffective disorder. Forty-seven of 59 (79.7%) patients were unemployed at baseline. Over a 12 months period, 23 (48.9%) of the patients achieved employment. Controlling for the duration of the illness and baseline scores, an analysis of covariance (ANCOVA) indicated the one and only significant time by group (remained unemployed vs. gained employment) interaction for verbal working memory as assessed by the Consonant Trigram Test (CTT) score. This interaction was due to significantly greater improvement in the patients who gained employment compared with those who remained unemployed. In addition, a logistic regression analysis with a forward stepwise procedure indicated that the CTT score at 12 months, followed by the CTT score at baseline and the duration of the illness, was the strong predictor of gaining employment.
Study 2: Work function and cognitive assessment data were collected in a sample of 152 patients with schizophrenia or schizoaffective disorder from the research clinic in Nashville. Thirty-two of 152 (21.1%) patients were employed. The age and duration of the illness were significantly less in employed patients. Comparison of those employed and unemployed groups showed significantly better Continuous Performance Test (CPT), CTT, Spatial Working Memory Test (SWMT), Brief Psychiatric Rating Scale (BPRS) Total and Positive scores in the employed group. A logistic regression analysis with a forward stepwise procedure indicated that the CTT score was the strongest predictor of employment status.
Study 3: Subjects were forty-six stabilized outpatients with schizophrenia. Subjective QoL and cognitive function were assessed using the Schizophrenia Quality of Life Scale (SQLS) and Brief Assessment of Cognition in Schizophrenia (BACS), respectively. Depressive symptoms were assessed with the Calgary Depression Scale for Schizophrenia (CDSS). Although the CDSS scores significantly correlated with the scores of all three SQLS subscales, among three SQLS subscales, only the Symptom/Side Effect subscale scores significantly correlated with the BACS Symbol Coding Task scores.
Conclusions: As predicated, neurocognitive performance was more importantly associated with employment status than clinical symptoms in patients with schizophrenia, and thus treatment that enhances cognitive function may lead to better employment outcome in these populations. Meanwhile, subjective QoL was more importantly associated with depressive symptoms than cognitive function, and therefore treatment for depressive symptoms may be important to improve QoL in patients with schizophrenia.

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