Depressive and negative symptoms in schizophrenia: different effects on clinical features

Abstract 

Objective

The primary aim of this study was to investigate whether depressive symptoms were significantly associated with functional outcome measures in a clinically stable group of outpatients with schizophrenia. We also analyzed whether depressive and negative symptoms presented different patterns of predictors.

Method

Seventy-eight consecutive outpatients meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria for schizophrenia in the stable period were enrolled in this cross-sectional study. Assessment were performed using the Calgary Depression Scale for Schizophrenia, Positive and Negative Syndromes Scale (PANSS), Clinical Global Impression Scale-severity, Social and Occupational Functioning Assessment Scale, Sheehan Disability Scale, and Quality of Life Scale. A neuropsychologic battery including the vocabulary and block design subtests of the Wechsler Adult Intelligence Scale-Revised, Wechsler Memory Scale, Wisconsin Card Sorting Test, and Continuous Performance Test was also administered to the patients. Two multiple regressions were performed testing demographic and clinical factors, rating scales, and cognitive measures as independent variables and Calgary Depression Scale for Schizophrenia and PANSS-negative subscale scores as dependent variables.

Results

Four variables were predictors of depressive symptoms in our sample of schizophrenic patients: 2 outcome measures (Sheehan Disability Scale and Quality of Life Scale), gender, and Continuous Performance Test reaction time. Predictors of negative symptoms were the measures of severity of psychopathology (Clinical Global Impression Scale-severity and PANSS-general psychopathology subscale) and the cognitive tests Wechsler Adult Intelligence Scale-Revised block design and Wechsler Memory Scale.

Conclusion

We found that depressive symptoms in schizophrenia are mainly a function of the level of social adjustment and quality of life, whereas negative symptoms constitute an indicator of severity of schizophrenia. The 2 symptom dimensions showed also distinct cognitive correlates.