Effects of Oxytocin on Negative Symptoms and Social Cognition in Schizophrenia and Its Possible Mechanisms

Effects of Oxytocin on Negative Symptoms and Social Cognition in Schizophrenia and Its Behavioral Mechanisms

The purpose of this study was to investigate the effects of oxytocin on negative symptoms and social cognitive task performance in schizophrenia. The investigators conducted a randomized, placebo-controlled trial testing the effects of twice daily intranasal oxytocin treatment for 14 days on psychotic symptoms and social cognition in patients with schizophrenia. The investigators hypothesize that PANSS scores will decline significantly and several social cognition measures will improved significantly or nearly significantly in oxytocin but not placebo recipients.

Social impairment is a primary cause of disability in schizophrenia, responds poorly to current antipsychotic medications and is related to deficits in social cognitive abilities, which include Theory of Mind, emotion recognition and attributional style. Oxytocin (OT) has many pro-social effects in animals and antipsychotic-like efficacy in preclinical tests. In this study, the investigators conducted a randomized, placebo-controlled trial testing the effects of twice daily intranasal oxytocin treatment for 14 days on psychotic symptoms and social cognition in patients with schizophrenia. The investigators will recruit patients with schizophrenia, screening of subjects included a review of psychiatric and medical history, physical examination, baseline social cognition measures were obtained followed by psychiatric ratings. Daily intranasal treatments were initiated after baseline assessments. Social cognition measures and psychiatric ratings were repeated beginning 50 min after the morning dose of study medication on treatment day 14. psychiatric ratings include The Positive and Negative Syndrome Scale (PANSS) and The Clinical Assessment Interview for Negative Symptoms (CAINS). The social cognition instruments are some social scales such as Toronto Alexithymia Scale, the Interpersonal Reactivity Index(IRI), and some computer tests such as reinforcement learning task and facial emotion identification test.

Inclusion criteria were:

1. aged between 18 and 55 years;
2. DSM-IV diagnosis of schizophrenia, acute schizophreniform disorder, or schizoaffective disorder.

Exclusion criteria were:

1. presence of other psychiatric diagnoses (e.g., depression);
2. active misuse of substance or alcohol;
3. intellectual disability (IQ < 70);
4. a history of neurological disorder.