- The prodromal phase of schizophrenic disorders has been described prospectively. The present study aimed to determine the short-term efficacy and safety of olanzapine treatment of prodromal symptoms compared with placebo.This was a double-blind, randomized, parallel-groups, placebo-controlled trial with fixed-flexible dosing conducted at four sites. Sixty patients met prodromal diagnostic criteria, including attenuated psychotic symptoms, as determined by structured interviews. Olanzapine 5-15 mg daily or placebo was prescribed for 8 weeks.In the mixed-effects, repeated-measures analysis, the treatment x time interaction for the change from baseline on the Scale of Prodromal Symptoms total score was statistically significant, and post hoc analyses revealed that the olanzapine-placebo difference reached p<.10 by week 6 and p<.05 at week 8. Ratings of extrapyramidal symptoms remained low in each group and were not significantly different. Olanzapine patients gained 9.9 lb versus.7 lb for placebo patients (p<.001).This short-term analysis suggests olanzapine is associated with significantly greater symptomatic improvement but significantly greater weight gain than is placebo in prodromal patients. Extrapyramidal symptoms with olanzapine were minimal and similar to those with placebo. Future research over the longer term with more patients will be needed before recommendations can be made regarding routine treatment.