A discriminant validity study of negative symptoms with a special focus on depression and antipsychotic medication.

If the construct validity of the negative symptom syndrome is to be established, the conceptual and operational overlap between negative symptoms and other syndromes such as depression and the effects of medication must be explained. The author assessed 26 patients with schizophrenia and 21 patients without schizophrenia, most of whom had depression, at the end of an average 2-week drug washout period and after approximately 2 months of psychotropic medication administration. Negative symptoms were remarkably consistent in patients with schizophrenia despite pharmacological intervention. In contrast, the patients without schizophrenia manifested significant decreases in negative symptoms.