The treatment of negative symptoms and deficit states of chronic schizophrenia: olanzapine compared to amisulpride and placebo in a 6‐month double‐blind controlled clinical trial

OBJECTIVE: The aim of the study was to evaluate the efficacy of olanzapine (5 and 20 mg/day) over a 6-month period in chronic schizophrenic patients experiencing predominantly negative symptoms. METHOD: Two hundred and forty-four patients participated in a 6-month multicenter double-blind trial of placebo (n = 34), olanzapine 5 mg/day (n = 70), olanzapine 20 mg/day (n = 70), or amisulpride 150 mg/day (n = 70). Primary measure was the scale for the assessment of negative symptoms. RESULTS: Olanzapine 5 mg/day showed significantly greater improvement than placebo in negative symptoms and in the Positive and Negative Syndrome Scale total score. Baseline positive symptoms were low at baseline and changed minimally. The neurological tolerance of olanzapine, amisulpride and placebo were comparable. CONCLUSION: Olanzapine 5 mg/day was effective in treating negative symptoms in a group of schizophrenic with predominantly negative symptoms during the stabilization phase. Improvement in positive symptoms or extrapyramidal symptoms (EPS) was unlikely to explain this result while improvement in depression may have partially contributed.