Obsessive-compulsive symptoms during treatment with olanzapine and risperidone: a prospective study of 113 patients with recent-onset schizophrenia or related disorders.

OBJECTIVE: To determine whether severity of obsessive-compulsive symptoms (OCS) differs during treatment with olanzapine or risperidone and to establish whether duration of antipsychotic treatment is related to severity of OCS.

METHOD: We conducted a prospective study of consecutively hospitalized young patients (mean age = 22.4 years) with DSM-IV schizophrenia or related disorders (N = 113) who were treated with olanzapine or risperidone. Olanzapine or risperidone was randomly prescribed for patients who were drug-naive or were treated with typical antipsychotics before admission (N = 36). Patients who had started olanzapine (N = 39) or risperidone treatment (N = 23) prior to admission continued with that medication if they showed initial clinical response. Patients who prior to admission started olanzapine (N = 6) or risperidone (N = 9) but showed no response or suffered from adverse effects switched at admission to risperidone or olanzapine, respectively. Medical records, parents, and patients revealed information on duration of treatment and compliance with olanzapine or risperidone prior to admission. The Yale-Brown Obsessive Compulsive Scale (YBOCS) was administered at admission and 6 weeks thereafter.

RESULTS: At baseline and 6-week assessments, OCS were found in about 30% of 106 evaluable cases and 15% met DSM-IV criteria for obsessive-compulsive disorder. No differences in OCS were found in the patients randomly assigned to olanzapine or risperidone. The 35 subjects treated with olanzapine at both assessments had significantly (p = .01) more severe OCS at week 6 than the 20 subjects treated with risperidone at both assessments. Duration of treatment with olanzapine was significantly (p < .01) related to severity of OCS.

CONCLUSION: There are no differences in the short-term propensity of olanzapine or risperidone to induce or exacerbate OCS. However, severity of OCS was associated with duration of treatment with olanzapine.