Comparison of risperidone and olanzapine in the control of negative symptoms of chronic schizophrenia and related psychotic disorders in patients aged 50 to 65 years.

Background: This analysis compares the efficacy of risperidone and olanzapine in controlling negative and positive symptoms of chronic psychosis in older patients.

Method: Post hoc assessments were made in a subset of risperidone-treated (N = 19) and olanzapine-treated (N = 20) older patients (aged 50 to 65 years) from a large international, multicenter, parallel, double-blind, 28-week study of patients aged 18 to 65 years (N = 339) randomly assigned to receive risperidone (4-12 mg/day) or olanzapine (10-20 mg/day). Assessments were made using repeated-measures analysis.

Results: At both 8 weeks and 28 weeks, the magnitude of changes in Positive and Negative Syndrome Scale (PANSS) positive symptom subscale scores did not differ between treatment groups (8 weeks: risperidone, -6.5; olanzapine, -6.8, p = .866; 28 weeks: risperidone, -6.5; olanzapine, -7.0; p = .804). However, by the 8-week timepoint, olanzapine had reduced PANSS negative subscale scores significantly more than risperidone (-8.8 vs. -4.9, p = .032). By the 28-week endpoint, olanzapine had continued to maintain significantly greater reduction in baseline-to-endpoint PANSS negative scores (-8.1 vs. -3.5, p = .032) and led to significantly greater reduction in scores on the Scale for the Assessment of Negative Symptoms (SANS) dimensions of affective flattening (-5.2 vs. -0.6, p = .033) and alogia (-3.8 vs. -0.3, p = .007). Patients in the olanzapine treatment group also demonstrated numerically greater reduction of both SANS summary (-3.7 vs. -1.0, p = .078) and SANS composite scores (-14.1 vs. -4.1, p = .075).

Conclusion: These data demonstrate that, in older patients with schizophrenia and related psychotic disorders, risperidone and olanzapine have approximately equal efficacy in controlling positive symptoms. However, olanzapine appears to be more efficacious in maintaining control over negative symptoms.