Schizophrenia and alcohol dependence: diverse clinical effects of oxytocin and their evolutionary origins

Systematic review and meta-analysis of reported adverse events of long-term intranasal oxytocin treatment for autism spectrum disorder

Recent studies have suggested oxytocin as a possible drug to treat social deficits caused by autism spectrum disorder (ASD), but the safety of intranasal oxytocin in autistic patients has not been established. The aim of this review was to characterize the side-effect profile of long-term intranasal oxytocin in treatment of ASD compared to placebo. All randomized controlled trials of intranasal oxytocin in the treatment of ASD published before 1 January 2017 that reported safety data were identified from databases, including PubMed, Embase, Cochrane Library, and International Pharmaceutical Abstract. Relevant data from the selected studies were then extracted for meta-analysis to estimate the pooled risk ratio for the most common adverse events. Descriptive analysis of severe adverse events was also conducted. Of the 223 participants in the five included studies, 123 were given oxytocin and 100 were given placebos. Nasal discomfort (14.3%), tiredness (7.2%), irritability (9.0%), diarrhea (4.5%), and skin irritation (4.5%) were the most common adverse events. None of these common adverse events was statistically associated with treatment allocation according to meta-analysis using pooled data (all P-values > 0.1). Five severe adverse events were reported, namely aggression (one in placebo, two in oxytocin) and seizures (one in placebo, one in oxytocin). Results from this systematic review support intranasal oxytocin as well tolerated and safe for use in the ASD population. Larger clinical trials should be conducted to establish the efficacy of intranasal oxytocin as a treatment of ASD.

Reversal of social deficits by subchronic oxytocin in two autism mouse models

Social deficits are a hallmark feature of autism spectrum disorder (ASD) and related developmental syndromes. Although there is no standard treatment for social dysfunction, clinical studies have identified oxytocin as a potential therapeutic with prosocial efficacy. We have previously reported that peripheral oxytocin treatment can increase sociability and ameliorate repetitive stereotypy in adolescent mice from the C58/J model of ASD-like behavior. In the present study, we determined that prosocial oxytocin effects were not limited to the adolescent period, since C58/J mice, tested in adulthood, demonstrated significant social preference up to 2 weeks following subchronic oxytocin treatment. Oxytocin was also evaluated in adult mice with underexpression of the N-methyl-d-aspartate receptor NR1 subunit (encoded by Grin1), a genetic model of autism- and schizophrenia-like behavior. Subchronic oxytocin had striking prosocial efficacy in male Grin1 knockdown mice; in contrast, chronic regimens with clozapine (66 mg/kg/day) or risperidone (2 mg/kg/day) failed to reverse deficits in sociability. Neither the subchronic oxytocin regimen, nor chronic treatment with clozapine or risperidone, reversed impaired prepulse inhibition in the Grin1 knockdown mice. Overall, these studies demonstrate oxytocin can enhance sociability in mouse models with divergent genotypes and behavioral profiles, adding to the evidence that this neurohormone could have therapeutic prosocial efficacy across a spectrum of developmental disorders.

Effects of oxytocin and genetic variants on brain and behaviour: Implications for treatment in schizophrenia

Impairments in social cognition and poor social functioning are core features of schizophrenia-spectrum disorders. In recent years, there has been a move towards developing new treatment strategies that specifically target social cognitive and social behavioural deficits. Oxytocin (OXT) is one such strategy that has gained increasing attention. There is a strong rationale for studying OXT in psychosis, from both an evolutionary perspective and neurodevelopmental-cognitive model of schizophrenia. Thus, the aim of this review was to critique and examine the observational and clinical oxytocin trial literature in schizophrenia-spectrum disorders. A handful of clinical trials suggest that OXT treatment may be beneficial for remediating social cognitive impairments, psychiatric symptoms, and improving social outcomes. However, inconsistencies exist in this literature, which may be explained by individual differences in the underlying neural response to OXT treatment and/or variation in the oxytocin and oxytocin receptor genes. Therefore, we additionally reviewed the evidence for structural and functional neural intermediate phenotypes in humans that link genetic variants to social behaviour/thinking, and discuss the implications of such interactions in the context of dysfunctional brain networks in schizophrenia. Factors that pose challenges for future OXT clinical research include the impact of age, sex, and ancestry, task-specific effects, bioavailability and pharmacokinetics, as well as neurotransmitter and drug interactions. While initial findings from OXT single dose/clinical trial studies are promising, more interdisciplinary research in both healthy and psychiatric populations is needed before determining whether OXT is a viable treatment option/adjunct for addressing poor illness outcomes in psychotic disorders.