Background: Schizophrenia is a disabling complex mental disorder and despite all available treatment, many patients unfortunately remain partial- or non-responders. A large body of research has shown that oxytocin is an important prosocial peptide and there is initial evidence that the central oxytocin system is altered in several mental disorders. The aim of this study was to test the efficacy of oxytocin, as augmentation therapy, in a sample of patients with schizophrenia.
Methods: We conducted an 8-month randomized, double-blind, controlled trial with a crossover design. We wanted to test the hypothesis that intranasal oxytocin could reduce symptoms in 32 patients with schizophrenia aged 18-45 with short-medium illness duration (<11 years). Patients were randomly assigned to either 40 International Units oxytocin once daily or a vehicle placebo group, in addition to their pre-study antipsychotic medication regimen. We subsequently conducted a multi-dimensional assessment including psychopathological, psychosocial and neuropsychological aspects.
Results: Positive and Negative Syndrome Scale scores showed no significant differences in treatment effects between the experimental group and controls. Furthermore, no treatment effects were shown in any of the rating scales used in this study. However, a statistically significant period effect was shown in most outcome measurements.
Conclusions: In our trial, oxytocin did not add any significant beneficial effects to anti-psychotic treatment in terms of clinical symptoms or psychosocial functioning. Further research should focus on different ways to administer oxytocin, or investigate predictors (such as past traumas, or biomarkers), which could identify subgroups of patients with different treatment responses to oxytocin. ClinicalTrials.gov Identifier: NCT01699997. ID number: RF-2010-2311148. URL: https://clinicaltrials.gov/ct2/show/NCT01699997.
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