Effects of Intranasal Administration of Oxytocin and Vasopressin on Social Cognition and Potential Routes and Mechanisms of Action

Effects of oxytocin administration on non-social executive functions in humans: a preregistered systematic review and meta-analysis

BACKGROUND

Oxytocin has received considerable research attention for its role in affiliative behaviors, particularly regarding its pro-social effects. More recent evidence has pointed to a broader role of oxytocin signaling, which includes non-social cognitive processes. However, meta-analytic data on oxytocin's effects on non-social cognition is currently limited.

METHODS

We registered plans for a systematic review and meta-analysis on the effects of oxytocin administration on non-social executive functions prior to data collection via a time-stamped protocol. We performed searches in PubMed, Europe PubMed Central, and the Bielefeld Academic Search Engine. We conducted a meta-analysis of 20 effect estimates from 13 eligible studies. Subgroup meta-analyses and a test for publication bias were also performed.

RESULTS

We found no overall significant effect of oxytocin administration on non-social executive functions (p = 0.30; Hedges' g = 0.07). However, effect sizes across sub-categories of executive function varied, where the effect of oxytocin administration was the largest for cognitive flexibility (p = 0.02; Hedges' g = 0.2). Publication bias was assessed using Robust Bayesian Meta-Analysis, which yielded moderate support for the absence of publication bias (BFPB = 0.32).

CONCLUSION

Our analysis suggests that oxytocin's effects may extend beyond social cognitive processing as data synthesis provided evidence supporting a role in non-social cognitive flexibility. The data and analysis output from this meta-analysis can be viewed in a point-and-click web application.

How does oxytocin modulate human behavior?

While the highly evolutionarily conserved hypothalamic neuropeptide, oxytocin (OT) can influence cognitive, emotional and social functions, and may have therapeutic potential in disorders with social dysfunction, it is still unclear how it acts. Here, we review the most established findings in both animal model and human studies regarding stimuli which evoke OT release, its primary functional effects and the mechanisms whereby exogenous administration influences brain and behavior. We also review progress on whether OT administration can improve social symptoms in autism spectrum disorder and schizophrenia and consider possible impediments to translational success. Importantly, we emphasize that OT acting via its extensive central or peripheral receptors primarily influences behavior indirectly through neuromodulatory interactions with classical transmitters and other peptides which themselves can independently influence behavior. We also emphasize that exogenous administration studies increasingly demonstrate peripheral effects of OT may be of greater importance than originally thought, especially involving the vagus. Overall, we propose a hierarchical model whereby OT's neuromodulatory actions influence behavior across interconnected functional domains and ultimately help to promote survival, security and sociability. Initially, OT potently facilitates attention to salient social and other important stimuli and additionally modulates cognitive, emotional and reward processing in a person- and context-dependent manner to promote interpersonal social understanding, attraction and bonds on the one hand and social group cohesion through increased conformity, altruistic punishment and moral emotions on the other. OT also increases co-operation and protection across both social domains. We hope this review and model will promote further research and help aid future translation success.

Nebulized vasopressin penetrates CSF and improves social cognition without inducing aggression in a rhesus monkey model of autism

Low cerebrospinal (CSF) arginine vasopressin (AVP) concentration is a biomarker of social impairment in low-social monkeys and children with autism, suggesting that AVP administration may improve primate social functioning. However, AVP administration also increases aggression, at least in "neurotypical" animals with intact AVP signaling. Here, we tested the effects of a voluntary drug administration method in low-social male rhesus monkeys with high autistic-like trait burden. Monkeys received nebulized AVP or placebo, using a within-subjects design. Study 1 (N = 8) investigated the effects of AVP administration on social cognition in two tests comparing responses to social versus nonsocial stimuli. Test 1: Placebo-administered monkeys lacked face recognition memory, whereas face recognition memory was "rescued" following AVP administration. In contrast, object recognition memory was intact and did not differ between administration conditions. Test 2: Placebo-administered monkeys did not respond to conspecific social communication cues, whereas following AVP administration, they reciprocated affiliative communication cues with species-typical affiliative responses. Importantly, AVP administration did not increase aggressive responses to conspecific aggressive or affiliative overtures. Study 2 (N = 4) evaluated the pharmacokinetics of this administration method. Following AVP nebulization, we observed a linear increase in cisternal CSF AVP levels, and a quadratic rise and fall in blood AVP levels. These findings indicate that nebulized AVP likely penetrates the central nervous system, selectively promotes species-typical responses to social information, and does not induce aggression in low-social individuals. Nebulized AVP therefore may hold promise for managing similar social symptoms in people with autism, particularly in very young or lower functioning individuals.

The Role of Oxytocin and Vasopressin in People with Borderline Personality Disorder: A Closer Look at Adolescents

Borderline personality disorder constitutes a significant medical challenge. Despite the fact that its occurrence among adolescents is currently attracting increasing interest from both clinicians and researchers, there is still insufficient data on this phenomenon. The etiology and maintenance of borderline personality disorder are not yet fully comprehended. Neuropeptides, including oxytocin and vasopressin, are considered to be involved in the development of this condition. The mechanism behind the actions of these neurohormones requires further investigation. Our work aims to collect and analyze the available research and existing hypotheses on the role of oxytocin and vasopressin in people with borderline personality disorder, with special attention drawn to adolescents suffering from this condition.

Exogenous oxytocin administered to induce or augment labour is positively associated with quality of observed mother-infant bonding

Oxytocin is a key hormone in the transition to motherhood. The maternal endogenous oxytocin system facilitates many physiological and biological adaptations, including breastfeeding, maternal wellbeing, and brain plasticity. Additionally, maternal endogenous oxytocin works as a finetuned orchestrator prior to, during, and after the birth of a child to support birth progression and mother-infant bonding. Exogenous oxytocin may be administered to induce or augment labour when this is not progressing naturally and is a common obstetric intervention worldwide. However, the lasting impact of these widely varying levels of systemic exogenous oxytocin on mother-infant bonding is currently unknown. This study aimed to investigate the association between exogenous oxytocin administered to induce or augment labour and quality of observed mother-infant bonding. Thirty-eight mother and infant dyads participated (mothers aged 24-48 years; infants aged 2-5 months). Mother-infant bonding quality was assessed via the Recorded Interaction Task and hospital birth records were consulted to obtain exogenous oxytocin administration data. Demographic information and possible confounding factors were collected from dyads, and salivary oxytocin concentration was measured for both mother and infant. Mother's perception of infant sleep difficulty was identified as a confounding factor for quality of mother-infant bonding. After controlling for the confounding factor, receiving exogenous oxytocin to induce or augment labour, as opposed to not, was found to be significantly positively associated with higher quality of observed mother-infant bonding (p = 0.029). These novel findings highlight the need for further exploration, both of the impact of the treatment and of the mechanisms of action of intrapartum exogenous oxytocin on the endogenous oxytocin system. It is argued that particular focus be given to investigate action on the central oxytocin receptors, and if this may play a role in subsequent mother-infant bonding outcomes. It is vital to understand the full breadth and the clinical implications of this commonplace procedure.

Neuroimaging and behavioral evidence of sex-specific effects of oxytocin on human sociality

Although the social role of oxytocin came to light due to sex-specific interactions such as mother-offspring bonding, current understanding of sex differences in the effects of oxytocin on human sociality is limited because of the predominance of all-male samples. With the increasing inclusion of females in intranasal oxytocin research, it is now possible to explore such patterns. Neuroimaging studies reveal relatively consistent sex-differential effects of oxytocin on the activation of brain regions associated with processing social stimuli - particularly the amygdala. Findings from behavioral research are varied but suggest that oxytocin more often facilitates social cognition and positive social interactions in males, with context-dependent effects in each sex. We discuss potential biological and psychological mechanisms underlying the reported sex differences, and conclude with considerations for future research and clinical applications of oxytocin.

Oxytocin enhances group-based guilt in high moral disengagement individuals through increased moral responsibility

Group-based guilt (collective guilt) refers to the negative emotions experienced when group members violate moral standards and can motivate prosocial behavior. Individuals exhibiting high levels of moral disengagement are prone to engaging in unethical conduct without experience of guilt, thereby prolonging or exacerbating conflicts and hindering conflict resolution. Oxytocin is believed to play key role in shaping social cognition and behaviors associated with morality and prosociality. So, this study (N = 79) explores oxytocin's potential to enhance group-based guilt and compensation for victims among individuals with high moral disengagement. Employing a randomized placebo-controlled design, participants received either oxytocin or placebo before undertaking a task designed to induce group-based guilt, during which they made decisions regarding the allocation of money to victims. Results revealed that participants with high moral disengagement who received oxytocin perceived higher levels of moral responsibility, experienced increased group-based guilt, and allocated significantly more money to victims compared to those who received the placebo. These findings suggested that oxytocin holds promise as an intervention to mitigate moral disengagement and foster moral behavior in individuals predisposed to avoiding responsibility and guilt feelings.

Hypothalamic circuits and aging: keeping the circadian clock updated

Over the past century, age-related diseases, such as cancer, type-2 diabetes, obesity, and mental illness, have shown a significant increase, negatively impacting overall quality of life. Studies on aged animal models have unveiled a progressive discoordination at multiple regulatory levels, including transcriptional, translational, and post-translational processes, resulting from cellular stress and circadian derangements. The circadian clock emerges as a key regulator, sustaining physiological homeostasis and promoting healthy aging through timely molecular coordination of pivotal cellular processes, such as stem-cell function, cellular stress responses, and inter-tissue communication, which become disrupted during aging. Given the crucial role of hypothalamic circuits in regulating organismal physiology, metabolic control, sleep homeostasis, and circadian rhythms, and their dependence on these processes, strategies aimed at enhancing hypothalamic and circadian function, including pharmacological and non-pharmacological approaches, offer systemic benefits for healthy aging. Intranasal brain-directed drug administration represents a promising avenue for effectively targeting specific brain regions, like the hypothalamus, while reducing side effects associated with systemic drug delivery, thereby presenting new therapeutic possibilities for diverse age-related conditions.

Intranasal oxytocin as a treatment for anxiety and autism: From subclinical to clinical applications

Animal and human studies have demonstrated that intranasal oxytocin (OT) can penetrate the brain and induce cognitive, emotional, and behavioral changes, particularly in social functioning. Consequently, numerous investigations have explored the potential of OT as a treatment for anxiety and autism, conditions characterized by social deficits. Although both subclinical and clinical studies provide converging evidence of the therapeutic effects of OT in reducing anxiety levels and improving social symptoms in autism, results are not always consistent. Additionally, the pharmacological mechanism of OT requires further elucidation for its effective clinical application. Therefore, this review aims to examine the contentious findings concerning the effects of OT on anxiety and autism, offer interpretations of the inconsistent results from the perspectives of individual differences and varying approaches to OT administration, and shed light on the underlying mechanisms of OT. Ultimately, standardization of dosage, frequency of administration, formulation characteristics, and nasal spray devices is proposed as essential for future human studies and clinical applications of OT treatment.

Effects of arginine vasopressin on human anxiety and associations with sex, dose, and V1a-receptor genotype

RATIONALE

Arginine vasopressin (AVP) has dose- and sex-specific effects on social behavior, and variation in social responses is related to variation in the V1a receptor gene in animals. Whether such complexity also characterizes AVP effects on anxiety in humans, or whether V1a genotype is related to anxiety and/or AVP's ability to affect it, remains to be determined.

OBJECTIVE

To test if AVP has dose-dependent effects on anxiety in men and/or women and if a particular allele within the RS3 promoter region of the V1a receptor gene is associated with anxiety and/or AVP effects on anxiety.

METHOD

Men and women self-administered 20 IU or 40 IU intranasal arginine vasopressin (AVP) and placebo in a double-blind, within-subjects design, and State (SA) and Trait (TA) anxiety were measured 60 min later. PCR was used to identify allelic variation within the RS3 region of the V1a receptor gene.

RESULTS

AVP decreased SA in men across both doses, whereas only the lower dose had the same effect, across sexes, in individuals who carry at least one copy of a previously identified "risk" allele in the RS3 promoter of the V1a receptor gene. Additionally, after placebo, women who carried a copy of the allele displayed lower TA than women who did not, and AVP acutely increased TA scores in those women.

CONCLUSIONS

Exogenous AVP has modest sex- and dose-dependent effects on anxiety/affect in humans. Further, allelic variation in the V1a promoter appears associated with responsiveness to AVP's effects and, at least in women, to stable levels of anxiety/affect.

Effects of systemic oxytocin receptor activation and blockade on risky decision making in female and male rats

The neuropeptide oxytocin is traditionally known for its roles in parturition, lactation, and social behavior. Other data, however, show that oxytocin can modulate behaviors outside of these contexts, including drug self-administration and some aspects of cost-benefit decision making. Here we used a pharmacological approach to investigate the contributions of oxytocin signaling to decision making under risk of explicit punishment. Female and male Long-Evans rats were trained on a risky decision-making task in which they chose between a small, "safe" food reward and a large, "risky" food reward that was accompanied by varying probabilities of mild footshock. Once stable choice behavior emerged, rats were tested in the task following acute intraperitoneal injections of oxytocin or the oxytocin receptor antagonist L-368,899. Neither drug affected task performance in males. In females, however, both oxytocin and L-368,899 caused a dose-dependent reduction in preference for large risky reward. Control experiments showed that these effects could not be accounted for by alterations in food motivation or shock sensitivity. Together, these results reveal a sex-dependent effect of oxytocin signaling on risky decision making in rats.

Pharmacological Treatment of Cognitive Impairment Associated With Schizophrenia: State of the Art and Future Perspectives

Cognitive Impairment Associated with Schizophrenia (CIAS) represents one of the core dimensions of Schizophrenia Spectrum Disorders (SSD), with an important negative impact on real-world functional outcomes of people living with SSD. Treatment of CIAS represents a therapeutic goal of considerable importance, and while cognition-oriented evidence-based psychosocial interventions are available, effective pharmacological treatment could represent a game-changer in the lives of people with SSD. The present critical review reports and discusses the evidence regarding the effects of several pharmacological agents that are available in clinical practice or are under study, commenting on both current and future perspectives of CIAS treatment. In particular, the effects on CIAS of antipsychotic medications, anticholinergic medications, benzodiazepines, which are currently commonly used in the treatment of SSD, and of iclepertin, d-serine, luvadaxistat, xanomeline-trospium, ulotaront, anti-inflammatory molecules, and oxytocin, which are undergoing regulatory trials or can be considered as experimental agents, will be reported and discussed. Currently, available pharmacological agents do not appear to provide substantial benefits on CIAS, but accurate management of antipsychotic medications and avoiding treatments that can further exacerbate CIAS represent important strategies. Some molecules that are currently being investigated in Phase 2 and Phase 3 trials have provided very promising preliminary results, but more information is currently required to assess their effectiveness in real-world contexts and to provide clear recommendations regarding their use in clinical practice. The results of ongoing and future studies will reveal whether any of these molecules represents the awaited pharmacological game-changer in the treatment of CIAS.

The Oxytocin Puzzle: Unlocking Alzheimer's Disease

Alzheimer's disease is a multi-factorial disease that disrupts many aspects of human behavior. In this comment, we highlight the work by Koulousakis et al. published in a recent issue of the Journal of Alzheimer's Disease. In this study, the authors tested the therapeutic potential of the neuropeptide oxytocin in a pre-clinical model of Alzheimer's disease and found positive behavioral outcomes on memory assessments. We discuss these findings in the context of oxytocin research in the field of Alzheimer's disease and the literature regarding oxytocin-based therapeutics, including administration protocols and potential underlying cellular and molecular mechanisms.

Intranasal oxytocin does not change partner preference in female titi monkeys (Plecturocebus cupreus), but intranasal vasopressin decreases it

Strong social bonds are critical to human health; however, the mechanisms by which social bonds are formed and maintained are still being elucidated. The neurohormones oxytocin (OT) and vasopressin (AVP) are considered likely candidates. Primate females, both human and nonhuman, remain understudied populations. Here, we conducted a pharmacological study coupled with a behavioral partner preference test (PPT) to better understand the mechanistic basis of attachment in adult female titi monkeys (Plecturocebus cupreus). This pair-bonding species shares a conserved form of oxytocin with humans and is an excellent model organism to study the neural basis of social bonding. We performed intranasal administration of three doses of oxytocin (IN-OT), two doses of vasopressin (IN-AVP), one dose of an oxytocin antagonist (IN-OTA) and one dose of a saline treatment. We found that compared to the saline control, the IN-AVP treatment (lower dose, 40 IU/kg) decreased the time spent in proximity to the partner and increased lip-smacking toward the stranger. We found no effects of IN-OT or IN-OTA manipulation on partner preference. In contrast, low-dose IN-AVP weakened the partner preference in female titi monkeys.

Sniffing oxytocin: Nose to brain or nose to blood?

In recent years ample studies have reported that intranasal administration of the neuropeptide oxytocin can facilitate social motivation and cognition in healthy and clinical populations. However, it is still unclear how effects are mediated since intranasally administered oxytocin can both directly enter the brain (nose to brain) and increase peripheral vascular concentrations (nose to blood). The relative functional contributions of these routes are not established and have received insufficient attention in the field. The current study used vasoconstrictor pretreatment to prevent intranasal oxytocin (24 IU) from increasing peripheral concentrations and measured effects on both resting-state neural (electroencephalography) and physiological responses (electrocardiogram, electrogastrogram and skin conductance). Results demonstrated that intranasal oxytocin alone produced robust and widespread increases of delta-beta cross-frequency coupling (CFC) from 30 min post-treatment but did not influence peripheral physiological measures. As predicted, vasoconstrictor pretreatment greatly reduced the normal increase in peripheral oxytocin concentrations and, importantly, abolished the majority of intranasal oxytocin effects on delta-beta CFC. Furthermore, time-dependent positive correlations were found between increases in plasma oxytocin concentrations and corresponding increases in delta-beta CFC following oxytocin treatment alone. Our findings suggest a critical role of peripheral vasculature-mediated routes on neural effects of exogenous oxytocin administration with important translational implications for its use as an intervention in psychiatric disorders.

Oxytocin and eating disorders: Knowledge gaps and future directions

Eating disorders continue to be a major public health issue and important cause of morbidity and premature mortality, particularly for young people. Yet in a concerning dialectic, this occurs in the context of an epidemic of obesity which, with its medical complications, constitutes another vexing public health challenge. While it is not an eating disorder per se obesity is often comorbid with eating disorders. Effective treatment for both eating disorders and obesity has proven to be elusive and in the search for novel therapeutic interventions, the prosocial, anxiolytic, brain plasticity and metabolic effects of oxytocin (OT) have been examined from this perspective. The availability of intranasal oxytocin (IN-OT) has led to a number of interventional treatment studies in anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED), their atypical and subclinical forms and in medical and psychiatric conditions co-occurring or comorbid with these, obesity with BED would be included here. The aim of this mini review is to collate recent findings on OT as a novel therapeutic intervention in eating disorders and obesity and to identify and address some of the knowledge gaps in the use of IN-OT. The wider clinical perspective utilised here might better address some of the gaps and identify future directions of research. Clearly much remains to be done for OT to fulfil its therapeutic promise in eating disorders. OT might yet be of therapeutic promise and will be appreciated where treatment advances have been hard to come by and prevention challenging for these disorders.

Oro-mucosal administration of oxytocin using medicated lollipops alters social attention, similar to intranasal and lingual routes: Implications for therapeutic use

A key functional effect of intranasal administration of the neuropeptide oxytocin is on top-down control of social attention. However, an oro-mucosal administration route may be better tolerated for chronic therapeutic use and evidence suggests that some functional effects of oxytocin can be mediated via peripheral routes. The current study investigated if oxytocin administered orally using medicated lollipops can both increase blood oxytocin concentrations and influence social attention and state anxiety. In a randomized, double-blind, clinical trial adult male participants received oral oxytocin (24IU) or placebo 30-min before completing a well-established anti-saccade paradigm which can assess treatment effects on both top-down and bottom-up attention. Oxytocin administration modulated top-down social attentional processing by increasing anti-saccade error rates on both social and non-social stimuli although it only increased response latencies for social cues. Anti-saccade errors were also positively associated with the proportionate increase in plasma oxytocin concentrations. A comparison analysis showed that oral oxytocin administration increased blood concentrations to a similar degree as given by lingual spray, although less than when given intranasally. Importantly, attentional and anxiolytic effects of oxytocin in the anti-saccade task were similar across intranasal, lingual, and oral administration routes. These findings demonstrate that oral administration of oxytocin, similar to via intranasal and lingual routes, can modulate top-down social attention and state anxiety and support its potential for therapeutic use. They also provide further evidence that functional effects of exogenously administered oxytocin can be mediated indirectly either by crossing the blood brain barrier or producing receptor mediated vagal stimulation, as opposed to via direct entry into the brain.

Oral Administration of Oxytocin, Like Intranasal Administration, Decreases Top-Down Social Attention

BACKGROUND

The neuropeptide oxytocin (OXT) modulates social cognition by increasing attention to social cues and may have therapeutic potential for impaired social attention in conditions such as autism spectrum disorder. Intranasal administration of OXT is widely used to examine the drug's functional effects in both adults and children and is assumed to enter the brain directly via this route. However, OXT can also influence brain function through increased blood concentrations, and we have recently shown that orally (lingual) administered OXT also modulates neural responses to emotional faces and may be better tolerated for therapeutic use. Here, we examine whether 24 IU OXT administered orally can facilitate social attention.

METHODS

In a randomized, placebo-controlled pharmacologic study, we used a validated emotional antisaccade eye-tracking paradigm to explore the effects of oral OXT on bottom-up and top-down attention processing in 80 healthy male participants.

RESULTS

Our findings showed that in terms of top-down attention, oral OXT increased errors for both social (angry, fearful, happy, sad, and neutral emotion faces) and nonsocial stimuli (oval shapes) in the antisaccade condition but increased response latencies only in the social condition. It also significantly reduced post-task state anxiety, but this reduction was not correlated with task performance. A comparison with our previous intranasal OXT study using the same task revealed that both routes have a similar effect on increasing antisaccade errors and response latencies and on reducing state anxiety.

CONCLUSIONS

Overall, our findings suggest that oral administration of OXT produces similar effects on top-down social attention control and anxiety to intranasal administration and may therefore have therapeutic utility.