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Background:Recent studies have reported that differences in cognitive performance between schizophrenic and bipolar patients seem to be smaller than expected. Patients with schizophrenia have consistently shown frontal executive dysfunctions, but studies regarding executive abilities in bipolar patients are scarce and discrepant. As executive function has been associated with psychosocial functioning in schizophrenia, we wanted to investigate if such a relationship is also present in bipolar disorder and the differences between the two groups. Methods:Executive function was assessed in 49 euthymic (at least 6 months in remission, Hamilton Depression Rating Scale ≤8 and Young Mania Rating Scale ≤6) bipolar and in 49 schizophrenic, residual-type (with at least 1 year without acute exacerbation and predominant negative symptomatology) patients, by the Wisconsin Card Sorting Test (WCST), FAS Test (COWAT) and Trail Making Test. Baseline clinical and psychosocial variables were controlled and psychopathology evaluated by means of the Positive and Negative Syndrome Scale (PANSS). Results:The two groups showed a similar pattern of cognitive deficits in tests of executive function, except for the number of categories achieved in the WCST, which was significantly lower in the schizophrenic group (F = 7.26; p = 0.009). Functional outcome was predicted by the negative syndrome (PANSSN) and perseverative errors (WCST) in schizophrenic patients, and general psychopathology (PANSSG) was the best predictor of functional outcome in the bipolar group. Conclusion:Executive function was a good predictor of functional outcome in the schizophrenic group, whereas clinical variables were more predictive of the bipolar one. Patterns of cognitive disturbances in tasks of executive function are similar in both groups but quantitatively more marked in schizophrenia.

The aim of the study was to analyze the role of clinical and neuropsychological variables in the psychosocial functioning and evolution of negative schizophrenia. We examined a sample of 49 negative schizophrenic outpatients who were pharmacologically stabilized. The subjects were evaluated clinically with the Positive and Negative Syndrome Scale (PANSS) and the Schedule for Affective Disorders and Schizophrenia (SADS), and neuropsychologically with a broad neuropsychological test battery. The correlations between all of the variables were studied and their predictive capacity assessed by linear regression methods. When the neuropsychological impairment criterion was established, we were able to distinguish two groups of patients with similar psychopathologies, but different neuropsychological and prognostic characteristics. Schizophrenic patients with neuropsychological impairment showed worse prognosis, worse evolution, and worse psychosocial adaptation than nonneuropsychologically impaired schizophrenics. Cognitive variables are statistically good predictors of evolution, prognosis, and adaptation. In conclusion, the negative syndrome of schizophrenia is neuropsychologically heterogeneous. Although negative patients present a similar clinical profile, their neuropsychological and prognostic characteristics may differ.