Obsessive-compulsive symptoms in schizophrenia: a comparison of olanzapine and placebo

The antipsychotic drug olanzapine is similar to clozapine and risperidone in potent serotonergic antagonism. We assessed obsessive-compulsive symptoms during olanzapine treatment because these symptoms have been reported during risperidone and clozapine treatment. Obsessions and compulsions were measured in 25 subjects with schizophrenia before and after a 6-week double-blind trial comparing two olanzapine doses to placebo. At baseline, 8 subjects had mild or moderate obsessions, and 6 had mild compulsions. There was no significant difference in the course of obsessive-compulsive symptoms among the three treatment groups. We found that olanzapine did not appear to cause obsessive-compulsive symptoms in patients with schizophrenia. Our sample size, the dose and duration of olanzapine treatment, and assessment methods limit the extent to which this finding can be generalized. Though emerging obsessive-compulsive symptoms have been reported for 13 clozapine-treated and 2 risperidone-treated patients with schizophrenia, this phenomenon has not yet been demonstrated in a controlled study.