The Effects Of Oxytocin On Negative Symptoms And Social Cognitive Function In Schizophrenia

Background and Objective: Schizophrenia is a severe neurodevelopmental disorder and results in marked functional impairment.Current pharmacologic treatments are inadequate,particularly for addressing negative and cognitive symptoms of the disorder.In recent years,many researches found that oxytocin could affect behaviors of human being and regulate social cognitive processing,which makes it possible for oxytocin to treat schizophrenia.This study aims to explore the effects of oxytocin on negative symptoms,social cognitive function and reward decision in schizophrenia and to reveal the behavioral mechanism for these effects.This will provide evidence for clinical practice of psychiatry.Methods: We conducted a randomized,double-blinded,placebo-controlled trial.Forty-three participants with schizophrenia were randomized to receive either intranasal oxytocin or a placebo solution(titrated to 24 IU twice a day,alternating between the left and right nostril)before breakfast and before dinner.Subjects remained on their pre-study medication regimen and doses throughout the treatment trial.We used The Clinical Assessment Interview for Negative Symptoms(CAINS),The Positive and Negative Syndrome Scale(PANSS)and Global Impressions-Severity scale(CGI-S)to assess clinical symptoms.Temporal Experience of Pleasure Scale(TEPS),Toronto Alexithymia Scale(TAS),Interpersonal Reactivity Index(IRI)and a facial emotion identification test(FEIT)were used to assess social cognitive function.We also conducted a reinforcement learning paradigm to measure reinforcement learning ability.We assessed the changes from baseline to two weeks of these variables.Results: 1.Treatment groups differed in the score pf the surprise recognition(t=-2.12,p=.04),specifically,the placebo group had significantly higher score in surprise recognition at baseline.There were no other significant baseline differences on demographic variables,clinical symptoms and social cognition scales.2.The oxytocin group had a significant reduction in CAINS total score(t=-2.70,p=.014),Motivation and pleasure(MAP)subscale score(t=-3.43,p=.003)and PANSS total score(t=-2.37,p=.028)and had a significant improvement in TEPS Contextual Anticipatory sub-score(t=2.737,p=.013).The placebo group had a significant reduction in PANSS general scale score(t=-2.50,p=.025).Regarding the performance of reinforcement learning,the oxytocin group had improvement in the gain pair accuracy during block4(t=2.49,p=.008),the win-stay rate across acquisition(t=2.28,p=.033),the total performance in the transfer phase(t=2.47,p=.023),the performance in reward context(t=2.72,p=.013)and the performance in lose context(t=2.11,p=.048).The placebo group had declined in the lose-shift rate across acquisition at two weeks(t=-3.22,p=.006).3.The repeated-measures analysis of variance(ANOVA)revealed there were significant time Χ group interaction in MAP score(F(1,1)=7.484,p=.01).Time had significant main effect in the general scale score(F(1,1)=7.693 P=.009),PANSS total score(F(1,1)=7.715,P=.009),TEPS Contextual Anticipatory sub-score(F(1,1)=4.399,p=.044),emotion(F(1,1)=4.24,p=.047),win-stay rate and lose-shift rate across acquisition(F(1,1)=5.383,p=.026,F(1,1)=8.806,p=.005).The group had significant main effect in the positive scale scores(F(1,35)=4.588 P=.039),distress(F(1,35)=5.431,p=.026),FEIT total score(F(1,35)=7.839,p=.008),happy(F(1,35)=4.30,p=.046),sad(F(1,35)=6.422,p=.016),surprise(F(1,35)=4.917,p=.033).Many variables of reinforcement learning task had time and group main effect.ANCOVAs controlling for baseline revealed that there were no significant reinforcement learning performance differences at two weeks between groups.Conclusion: The intranasal oxytocin treatment for 14 days can reduce negative symptoms in male patients with schizophrenia,while had no any significant beneficial effects to social cognitive functions and reinforcement learning abilities.