Adjunctive Intranasal Oxytocin Reduces Symptoms in Schizophrenia Patients

Background: Both human and animal studies suggest oxytocin may have antipsychotic properties. Therefore, we conducted a clinical trial to directly test this notion. Methods: Nineteen schizophrenia patients with residual symptoms despite being on a stable dose of at least one antipsychotic were enrolled in a randomized, double-blind, crossover study. They received 3 weeks of daily intranasal oxytocin (titrated to 40 IU twice a day) and placebo adjunctive to their antipsychotics. Order of intranasal treatment was randomly assigned and there was a 1-week washout between treatments. Results: Analysis of the 15 subjects who completed all the study visits revealed that oxytocin significantly reduced scores on the Positive and Negative Symptom Scale (p < .001) and Clinical Global Impression-Improvement Scale (p < .001) compared with placebo at the 3-week end point. No benefit was seen at the early time points. Oxytocin was well tolerated and produced no adverse effects based upon patient reports or laboratory analysis. Conclusions: The results support the hypothesis that oxytocin has antipsychotic properties and is well tolerated. Higher doses and longer duration of treatment may produce larger benefits and should be evaluated in future studies.