Oxytocin, but not vasopressin, impairs social cognitive ability among individuals with higher levels of social anxiety: a randomized controlled trial

Null results of oxytocin and vasopressin administration on mentalizing in a large fMRI sample: evidence from a randomized controlled trial

BACKGROUND

Although potential links between oxytocin (OT), vasopressin (AVP), and social cognition are well-grounded theoretically, most studies have included all male samples, and few have demonstrated consistent effects of either neuropeptide on mentalizing (i.e. understanding the mental states of others). To understand the potential of either neuropeptide as a pharmacological treatment for individuals with impairments in social cognition, it is important to demonstrate the beneficial effects of OT and AVP on mentalizing in healthy individuals.

METHODS

In the present randomized, double-blind, placebo-controlled study (n = 186) of healthy individuals, we examined the effects of OT and AVP administration on behavioral responses and neural activity in response to a mentalizing task.

RESULTS

Relative to placebo, neither drug showed an effect on task reaction time or accuracy, nor on whole-brain neural activation or functional connectivity observed within brain networks associated with mentalizing. Exploratory analyses included several variables previously shown to moderate OT's effects on social processes (e.g., self-reported empathy, alexithymia) but resulted in no significant interaction effects.

CONCLUSIONS

Results add to a growing literature demonstrating that intranasal administration of OT and AVP may have a more limited effect on social cognition, at both the behavioral and neural level, than initially assumed. Randomized controlled trial registrations: ClinicalTrials.gov; NCT02393443; NCT02393456; NCT02394054.

Oxytocin: An Old Hormone, A Novel Psychotropic Drug And Possible Use In Treating Psychiatric Disorders

BACKGROUND

Oxytocin is a nonapeptide synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. Historically, this molecule has been involved as a key factor in the formation of infant attachment, maternal behavior and pair bonding and, more generally, in linking social signals with cognition, behaviors and reward. In the last decades, the whole oxytocin system has gained a growing interest as it was proposed to be implicated in etiopathogenesis of several neurodevelopmental and neuropsychiatric disorders.

METHODS

With the main goal of an in-depth understanding of the oxytocin role in the regulation of different functions and complex behaviors as well as its intriguing implications in different neuropsychiatric disorders, we performed a critical review of the current state of art. We carried out this work through PubMed database up to June 2021 with the search terms: 1) "oxytocin and neuropsychiatric disorders"; 2) "oxytocin and neurodevelopmental disorders"; 3) "oxytocin and anorexia"; 4) "oxytocin and eating disorders"; 5) "oxytocin and obsessive-compulsive disorder"; 6) "oxytocin and schizophrenia"; 7) "oxytocin and depression"; 8) "oxytocin and bipolar disorder"; 9) "oxytocin and psychosis"; 10) "oxytocin and anxiety"; 11) "oxytocin and personality disorder"; 12) "oxytocin and PTSD".

RESULTS

Biological, genetic, and epigenetic studies highlighted quality and quantity modifications in the expression of oxytocin peptide or in oxytocin receptor isoforms. These alterations would seem to be correlated with a higher risk of presenting several neuropsychiatric disorders belonging to different psychopathological spectra. Collaterally, the exogenous oxytocin administration has shown to ameliorate many neuropsychiatric clinical conditions.

CONCLUSION

Finally, we briefly analyzed the potential pharmacological use of oxytocin in patient with severe symptomatic SARS-CoV-2 infection due to its anti-inflammatory, anti-oxidative and immunoregulatory properties.

Social anxiety is associated with greater peripheral oxytocin reactivity to psychosocial stress

To date, it has been difficult to establish reliable biomarkers associated with specific forms of psychopathology. Social anxiety, for example, is associated with inconsistent biological responses to psychosocial stress on markers including cortisol and salivary alpha-amylase. Thus, it is critical that studies identify more reliable biomarkers that index patterns associated with social anxiety. Two potential candidates are the neuropeptides oxytocin and vasopressin, which have been implicated in stress responsivity across species. Studies have demonstrated a reliable increase in oxytocin, and a surrogate marker for vasopressin, following engagement in the most widely used lab-based psychosocial stress paradigm: the Trier Social Stress Test (TSST). However, no study has examined whether social anxiety moderates peripheral oxytocin or vasopressin reactivity to psychosocial stress. In 101 young adult participants, dimensionally assessed social anxiety was associated with greater plasma oxytocin, but not vasopressin, reactivity to the TSST. Results were maintained following the inclusion of depression as a covariate. Findings suggest that studying changes in peripheral oxytocin concentrations may be a method of differentiating individuals with higher levels of social anxiety.

The Role of the Oxytocin System in Anxiety Disorders

Oxytocin, a neuropeptide synthesized by the hypothalamus, plays a central role in human social behavior, social cognition, anxiety, mood, stress modulation, and fear learning and extinction. The relationships between oxytocin and psychiatric disorders including depression, anxiety, schizophrenia, and autism spectrum disorder have been extensively studied. In this chapter, we focus on the current knowledge about oxytocin and anxiety disorder. We discuss the anxiolytic effects of oxytocin in preclinical and clinical findings, possible related neurobehavioral mechanisms (social cognition, fear learning, and extinction), related neurotransmitter and neuroendocrine systems (hypothalamus-pituitary-adrenal axis, serotoninergic, and GABAergic systems), and studies regarding plasma levels of oxytocin, genetic and epigenetic findings, and effects of intranasal oxytocin in DSM-5 anxiety disorder (primarily social anxiety disorder and separation anxiety disorder) patients.

Null results of oxytocin and vasopressin administration across a range of social cognitive and behavioral paradigms: Evidence from a randomized controlled trial

Research examining oxytocin and vasopressin in humans has the potential to elucidate neurobiological mechanisms underlying human sociality that have been previously unknown or not well characterized. A primary goal of this work is to increase our knowledge about neurodevelopmental and psychiatric disorders characterized by impairments in social cognition. However, years of research highlighting wide-ranging effects of, in particular, intranasal oxytocin administration have been tempered as the fields of psychology, neuroscience, and other disciplines have been addressing concerns over the reproducibility and validity of research findings. We present a series of behavioral tasks that were conducted using a randomized, double-blind, placebo controlled, between-subjects design, in which our research group found no main effects of oxytocin and vasopressin on a host of social outcomes. In addition to null hypothesis significance testing, we implemented equivalence testing and Bayesian hypothesis testing to examine the sensitivity of our findings. These analyses indicated that 47-83% of our results (depending on the method of post-hoc analysis) had enough sensitivity to detect the absence of a main effect. Our results add to evidence that intranasal oxytocin may have a more limited direct effect on human social processes than initially assumed and suggest that the direct effects of intranasal vasopressin may be similarly limited. Randomized controlled trial registration: NCT01680718.

A role for the CD38 rs3796863 polymorphism in alcohol and monetary reward: evidence from CD38 knockout mice and alcohol self-administration, [11C]-raclopride binding, and functional MRI in humans

Background: Cluster of differentiation 38 (CD38) is a transmembrane protein expressed in dopaminergic reward pathways in the brain, including the nucleus accumbens (NAc). The GG genotype of a common single nucleotide polymorphism (SNP) within CD38, rs3796863, is associated with increased social reward.Objective: Examine whether CD38 rs3796863 and Cd38 knockout (KO) are associated with reward-related neural and behavioral phenotypes.Methods: Data from four independent human studies were used to test whether rs3796863 genotype is associated with: (1) intravenous alcohol self-administration (n = 64, 30 females), (2) alcohol-stimulated dopamine (DA) release measured using ¹¹C-raclopride positron emission tomography (n = 22 men), (3) ventral striatum (VS) response to positive feedback measured using a card guessing functional magnetic resonance imaging (fMRI) paradigm (n = 531, 276 females), and (4) resting state functional connectivity (rsfc) of the VS (n = 51, 26 females). In a fifth study, we used a mouse model to examine whether cd38 knockout influences stimulated DA release in the NAc core and dorsal striatum using fast-scanning cyclic voltammetry.Results: Relative to T allele carriers, G homozygotes at rs3796863 within CD38 were characterized by greater alcohol self-administration, alcohol-stimulated dopamine release, VS response to positive feedback, and rsfc between the VS and anterior cingulate cortex. High-frequency stimulation reduced DA release among Cd38 KO mice had reduced dopamine release in the NAc.Conclusion: Converging evidence suggests that CD38 rs3796863 genotype may increase DA-related reward response and alcohol consumption.

Intranasal oxytocin modulates higher order social cognition in body dysmorphic disorder

BACKGROUND

Body dysmorphic disorder (BDD) is a psychiatric disorder with specific impairments in social cognition related to excessive concerns about one's appearance. Individuals with BDD have difficulty identifying emotional expressions and attribute internal factors for others' emotional expressions in self-referent (but not other-referent) scenarios. Given the role of oxytocin in regulating social approach behavior and social salience, we hypothesized that oxytocin would improve biases in emotion recognition, attributions, and threat interpretations in individuals with BDD, compared to healthy controls (HCs). This is the first study to examine the effects of oxytocin in people with BDD.

METHODS

Eighteen participants with BDD and 16 HCs received a single dose of 24 international units of intranasal oxytocin (Syntocinon®) or matching placebo in a randomized, placebo-controlled, within-subject crossover design. Participants completed the Emotion Recognition Task and Interpretation Questionnaire 45 min after administration.

RESULTS

Oxytocin, relative to placebo, did not improve emotion recognition accuracy in either self-referent or other-referent contexts for individuals with BDD. However, oxytocin led to greater internal attributions in other-referent contexts for those with BDD compared to HCs. Rather than reducing self-blame, oxytocin led to other-directed blame. Oxytocin did not impact threat interpretations in BDD.

CONCLUSIONS

Oxytocin may only impact specific aspects of higher order social cognition in BDD and may have unwanted effects on emotion attributions. Our results caution its clinical use in BDD.

Epigenetic regulation of the oxytocin receptor is associated with neural response during selective social attention

Aberrant attentional biases to social stimuli have been implicated in a number of disorders including autism and social anxiety disorder. Oxytocin, a naturally-occurring mammalian hormone and neuromodulator involved in regulating social behavior, has been proposed to impact basic biological systems that facilitate the detection of and orientation to social information. Here, we investigate a role for naturally-occurring variability in the endogenous oxytocinergic system in regulating neural response during attention to social information. Participants performed a selective social attention task while undergoing fMRI, provided a blood sample for epigenetic analysis, and completed self-report measures of social functioning. We find that a functional epigenetic modification to the oxytocin receptor, OXTR methylation, is associated with increased neural response within and decreased functional coupling between regions of the salience and attentional control networks during selective social attention. We also show that subclinical variability in autistic and social anxiety traits moderates this epigenetic regulation of neural response. These data offer a mechanistic explanation to a growing literature associating social behavior and disorder with epigenetic modification to OXTR by suggesting that OXTR methylation reflects a decrease in the extent to which social information automatically captures attention. We highlight the importance that treatment efficacy be considered in relation to individual differences in molecular makeup, and that future studies aimed at uncovering biomarkers of disorder carefully consider measurement at both the biological and phenotypic level.

Electrophysiological correlates of oxytocin-induced enhancement of social performance monitoring

Altered performance monitoring has been demonstrated after administration of different pharmacological compounds and in various clinical populations, such as excessive neurophysiological responses to mistakes in anxiety disorders. Here, a novel social pharmacological approach was applied to investigate whether oxytocin administration (24 IU) enhances performance monitoring for errors that have negative consequences for another individual, so-called social mistakes. Healthy male volunteers (N = 24) participated in a placebo-controlled crossover design. EEG measures were obtained while pairs of participants performed a speeded choice reaction-time task in an individual and social context. Following oxytocin administration, error-related negativity amplitudes were increased for social compared with individual mistakes. This increase was not found in the placebo condition. No effects of oxytocin were present in the individual context. The current study shows that oxytocin enhances performance monitoring specifically for social mistakes. This outcome is in line with a presumed role for oxytocin in salience attribution to social cues and underlines its context-dependency. Combining these processes may thus open up new research avenues and advance our understanding of individual differences in performance monitoring and oxytocin responses from a social neurocognitive, pharmacological and clinical perspective.

Intranasal oxytocin does not reduce age-related difficulties in social cognition

Oxytocin is a neuropeptide that plays a key role in social processing and there are several studies suggesting that intranasally administered oxytocin may enhance social cognitive abilities and visual attention in healthy and clinical groups. However, there are very few studies to date that have investigated the potential benefits of intranasal oxytocin (iOT) on older adults' social cognitive abilities. This is a surprising omission, because relative to their younger counterparts, older adults also exhibit a range of social cognitive difficulties and also show differences in the way they visually attend to social information. Therefore, we tested the effect of iOT (24 IU) versus a placebo spray on 59 older and 61 younger adults' social cognitive abilities and visual attention using a double-blind placebo-controlled within-groups design. While iOT provided no overall age-related benefit on social cognitive abilities, the key finding to emerge was that iOT improved ToM ability in both age-groups when the task had minimal contextual information, but not when the task had enriched contextual information. Interestingly, iOT had gender specific effects during a ToM task with minimal context. For males in both age-groups, iOT reduced gazing to the social aspects of the scenes (i.e., faces & bodies), and for females, iOT eliminated age differences in gaze patterns that were observed in the placebo condition. These effects on eye-gaze were not observed in a very similar ToM task that included more enriched contextual information. Overall, these findings highlight the interactive nature of iOT with task related factors (e.g., context), and are discussed in relation to the social salience hypothesis of oxytocin.

Oxytocin and Anxiety Disorders: Translational and Therapeutic Aspects

PURPOSE OF REVIEW

This review aims to evaluate the most recent literature examining the oxytocin (OXT) system's role in human anxiety by surveying various fields of preclinical and clinical research supporting this role, and queries whether the OXT system might be a target for novel anxiolytics.

RECENT FINDINGS

Evidence from the diverse body of literature presented here, from translational research, genetic and neuroimaging studies, to clinical trials of intranasal (IN) OXT reveals a positive association. In addition, some moderators (e.g., sex, specificities to cues) of OXT's anxiolytic effects can have an important influence on its outcomes, awaiting further research. Evidence for the role of OXT in regulating anxiety is undeniable. We expect that the diverse particularities of the OXT system will help broaden our understanding of anxiety and stress-related disorders. We conclude that OXT promises an enticing treatment option for human anxiety disorders especially those associated with socio-emotional dysfunctions.

Gender differences in social anxiety disorder: A review

Gender differences in social anxiety disorder (SAD) have not received much empirical attention despite the large body of research on the disorder, and in contrast to significant literature about gender differences in other disorders such as depression or posttraumatic stress disorder. To address this gap, we comprehensively reviewed the literature regarding gender differences in eight domains of SAD: prevalence, clinical presentation, functioning and impairment, comorbidity, course, treatment seeking, physiological arousal, and the oxytocin system. Findings from the present review indicate that women are more likely to have SAD and report greater clinical severity. Notwithstanding, men with the disorder may seek treatment to a greater extent. According to the present review, the course of SAD seems to be similar for men and women, and findings regarding gender differences in functional impairment and comorbidity are inconclusive. We highlight areas requiring future research and discuss the findings in the context of a number of theoretical perspectives. We believe that further research and integration of scientific findings with existing theories is essential in order to increase our understanding and awareness of gender differences in SAD, thus facilitating gender-sensitive and specifically-tailored interventions for both men and women with the disorder.

Oxytocin Increases the Perceived Value of Both Self- and Other-Owned Items and Alters Medial Prefrontal Cortex Activity in an Endowment Task

The neuropeptide oxytocin (OXT) can influence self-processing and may help motivate us to value the attributes of others in a more self-like manner by reducing medial prefrontal cortex (mPFC) responses. We do not know however whether this OXT effect extends to possessions. We tend to place a higher monetary value on specific objects that belong to us compared to others, known as the "endowment effect". In two double-blind, between-subject placebo (PLC) controlled experiments in subjects from a collectivist culture, we investigated the influence of intranasal OXT on the endowment effect, with the second study incorporating functional magnetic resonance imaging (fMRI). In the task, subjects decided whether to buy or sell their own or others' (mother/father/classmate/stranger) possessions at various prices. Both experiments demonstrated an endowment effect in the self-owned condition which extended to close others (mother/father) and OXT increased this for self and all other-owned items. This OXT effect was associated with reduced activity in the ventral mPFC (vmPFC) in the self-owned condition but increased in the mother-condition. For the classmate- and stranger-owned conditions OXT increased activity in the dorsal mPFC (dmPFC). Changes in vmPFC activation were associated with the size of the endowment effect for self- and mother-owned items. Functional connectivity between the dmPFC and ventral striatum (VStr) was reduced by OXT in self- and mother-owned conditions and between vmPFC and precuneus in the self-condition. Overall our results show that OXT enhances the endowment effect for both self- and other-owned items in Chinese subjects. This effect is associated with reduced mPFC activation in the self-condition but enhanced activation in all other-conditions and involves differential actions on both dorsal and ventral regions as well as functional connectivity with brain reward and other self-processing regions. Overall our findings suggest that OXT increases the perceived value of both self- and other-owned items by acting on neural circuitry involved in self-processing and reward.

Oxytocin effects in schizophrenia: Reconciling mixed findings and moving forward

Schizophrenia is a severe mental illness that causes major functional impairment. Current pharmacologic treatments are inadequate, particularly for addressing negative and cognitive symptoms of the disorder. Oxytocin, a neuropeptide known to moderate social behaviors, has been investigated as a potential therapeutic for schizophrenia in recent years. Results have been decidedly mixed, leading to controversy regarding oxytocin's utility. In this review, we outline several considerations for interpreting the extant literature and propose a focused agenda for future work that builds on the most compelling findings regarding oxytocin effects in schizophrenia to date. Specifically, we examine underlying causes of heterogeneity in randomized clinical trials (RCTs) conducted thus far and highlight the complexity of the human oxytocin system. We then review evidence of oxytocin's effects on specific deficits in schizophrenia, arguing for further study using objective, precise outcome measures in order to determine whether oxytocin has the potential to improve functional impairment in schizophrenia.

Increased oxytocin levels among abstinent heroin addicts: Association with aggressiveness, psychiatric symptoms and perceived childhood neglect

A disruption of the oxytocin system seems to affect a variety of brain functions including emotions, mood and social behavior possibly underlying severe social deficits and susceptibility for substance use and mental health disorders. Early life adversity, such as insecure attachment in childhood, has been suggested to influence oxytocin tone contributing to a condition of neurobiological vulnerability. Aim of the present study was to investigate oxytocin serum levels in abstinent heroin addicted patients, in comparison with healthy controls, and the possible correlation with co-occurring psychiatric symptoms, aggressiveness and perception of parental neglect. Eighteen (18) abstinent patients, affected by heroin use disorders, and 18 control subjects, who never used drugs or abused alcohol, were included in the study and submitted to 1) collection of a blood sample for oxytocin assay, 2) Symptoms Check List 90 for psychiatric symptoms evaluation 3) Buss Durkee Hostility Inventory to measure aggressiveness 4) Child Experience of Care and Abuse-Questionnaire to retrospectively test the perception of parental neglect. Heroin exposure extent and heroin dosages were also recorded. Oxytocin serum levels were unexpectedly significantly higher among abstinent patients affected by heroin use disorders and positively correlated with psychiatric symptoms, aggressiveness and mother neglect scores. No correlation was evidenced between oxytocin and heroin exposure extent or dosages. Our findings appear to contradict the simplistic view of oxytocin as a pro-social hormone and confirm previous evidence concerning the peptide levels direct association with aggressive behavior and mood disorders. Considering a more complex mechanism, oxytocin would increase the sensitivity to social salience cues related to contextual or inter-individual factors, promoting pro-sociality in "safe" conditions and, in contrast, inducing more defensive and "anti-social" emotions and behaviors when the social cues are interpreted as "unsafe". This latter condition is often characterizing the clinical history of addicted patients.

Oxytocin and Anxiety Disorders

In the present chapter, we review the literature focusing on oxytocin (OT)-centered research in anxiety spectrum conditions, comprising separation anxiety disorder, specific phobias, social anxiety disorder (SAD), panic disorder, generalized anxiety disorder, and anxiety-related endophenotypes (e.g., trust behavior, behavioral inhibition, neuroticism, and state/trait anxiety). OT receptor gene (OXTR) polymorphisms have been implicated in gene-environment interactions with attachment style and childhood maltreatment and to influence clinical outcomes, including SAD intensity and limbic responsiveness. Epigenetic OXTR DNA methylation patterns have emerged as a link between categorical, dimensional, neuroendocrinological, and neuroimaging SAD correlates, highlighting them as potential peripheral surrogates of the central oxytocinergic tone. A pathophysiological framework of OT integrating the dynamic nature of epigenetic biomarkers and the summarized genetic and peripheral evidence is proposed. Finally, we emphasize opportunities and challenges of OT as a key network node of social interaction and fear learning in social contexts. In conjunction with multi-level investigations incorporating a dimensional understanding of social affiliation and avoidance in anxiety spectrum disorders, these concepts will help to promote research for diagnostic, state, and treatment response biomarkers of the OT system, advancing towards indicated preventive interventions and personalized treatment approaches.