Oxytocin and Interpersonal Relationships

A translational neuroscience perspective on loneliness: Narrative review focusing on social interaction, illness and oxytocin

This review addresses key findings on loneliness from the social, neurobiological and clinical fields. From a translational perspective, results from studies in humans and animals are included, with a focus on social interaction, mental and physical illness and the role of oxytocin in loneliness. In terms of social interactions, lonely individuals tend to exhibit a range of abnormal behaviors based on dysfunctional social cognitions that make it difficult for them to form meaningful relationships. Neurobiologically, a link has been established between loneliness and the hypothalamic peptide hormone oxytocin. Since social interactions and especially social touch regulate oxytocin signaling, lonely individuals may have an oxytocin imbalance, which in turn affects their health and well-being. Clinically, loneliness is a predictor of physical and mental illness and leads to increased morbidity and mortality. There is evidence that psychopathology is both a cause and a consequence of loneliness. The final section of this review summarizes the findings from social, neurobiological and clinical perspectives to present a new model of the complex construct of loneliness.

Convergence of oxytocin and dopamine signalling in neuronal circuits: Insights into the neurobiology of social interactions across species

Social behaviour is essential for animal survival, and the hypothalamic neuropeptide oxytocin (OXT) critically impacts bonding, parenting, and decision-making. Dopamine (DA), is released by ventral tegmental area (VTA) dopaminergic neurons, regulating social cues in the mesolimbic system. Despite extensive exploration of OXT and DA roles in social behaviour independently, limited studies investigate their interplay. This narrative review integrates insights from human and animal studies, particularly rodents, emphasising recent research on pharmacological manipulations of OXT or DA systems in social behaviour. Additionally, we review studies correlating social behaviour with blood/cerebral OXT and DA levels. Behavioural facets include sociability, cooperation, pair bonding and parental care. In addition, we provide insights into OXT-DA interplay in animal models of social stress, autism, and schizophrenia. Emphasis is placed on the complex relationship between the OXT and DA systems and their collective influence on social behaviour across physiological and pathological conditions. Understanding OXT and DA imbalance is fundamental for unravelling the neurobiological underpinnings of social interaction and reward processing deficits observed in psychiatric conditions.

Photoswitchable Probes of Oxytocin and Vasopressin

Oxytocin (OT) and vasopressin (VP) are related neuropeptides that regulate many biological processes. In humans, OT and VP act via four G protein-coupled receptors, OTR, V1aR, V1bR, and V2R (VPRs), which are associated with several disorders. To investigate the therapeutic potential of these receptors, particularly in the receptor-dense areas of the brain, molecular probes with a high temporal and spatial resolution are required. Such a spatiotemporal resolution can be achieved by incorporating photochromic moieties into OT and VP. Here, we report the design, synthesis, and (photo)pharmacological characterization of 12 OT- and VP-derived photoprobes using different modification strategies. Despite OT's and VP's sensitivity toward structural changes, we identified two photoprobes with good potency and photoswitch window for investigating the OTR and V1bR. These photoprobes should be of high value for producing cutting-edge photocontrollable peptide probes for the study of dynamic and kinetic receptor activation processes in specific regions of the brain.

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

Acute and chronic administration of intranasal oxytocin and vasopressin have been extensively utilized in both animal models and human preclinical and clinical studies over the last few decades to modulate various aspects of social cognition and their underlying neural mechanisms, although effects are not always consistent. The use of an intranasal route of administration is largely driven by evidence that it permits neuropeptides to penetrate directly into the brain by circumventing the blood-brain barrier, which has been considered relatively impermeable to them. However, this interpretation has been the subject of considerable debate. In this review, we will focus on research in both animal models and humans, which investigates the different potential routes via which these intranasally administered neuropeptides may be producing their various effects on social cognition. We will also consider the contribution of different methods of intranasal application and additionally the importance of dose magnitude and frequency for influencing G protein-coupled receptor signaling and subsequent functional outcomes. Overall, we conclude that while some functional effects of intranasal oxytocin and vasopressin in the domain of social cognition may result from direct penetration into the brain following intranasal administration, others may be contributed by the neuropeptides either entering the peripheral circulation and crossing the blood-brain barrier and/or producing vagal stimulation via peripheral receptors. Furthermore, to complicate matters, functional effects via these routes may differ, and both dose magnitude and frequency can produce very different functional outcomes and therefore need to be optimized to produce desired effects.

Interpersonal Coordination in Schizophrenia: A Scoping Review of the Literature

Interpersonal coordination forms the natural bridge between the self and others. It arises from the dynamic and complex set of embodied processes that involve nonverbal behaviors, perceptions, movement, and emotions that support adaptive interactions. Disembodiment has been implicated in a myriad of core clinical phenomena that manifest in a "praecox feeling" in persons with schizophrenia during interpersonal interactions. To further understand mechanisms underlying aberrant interpersonal interactions in schizophrenia, recent research has focused on mimicry, imitation, and interactional synchrony. In this study, we conducted a Pubmed, Web of Science, and PsycInfo database review of the literature on interpersonal coordination in schizophrenia to evaluate the body of work in mimicry, imitation, and interactional synchrony in relation to schizophrenia-spectrum conditions. The results of the review suggest that the sensory-motor processes underlying interpersonal coordination may result in impaired abilities to mimic and synchronize nonverbal behavior during interactions. Opportunities for future progress lie in studies of interpersonal coordination at different developmental stages of psychosis, potential use of interpersonal coordination to improve treatment adherence and reduce stigma, as well as interventions to improve social functioning in people with a serious mental illness.

Oxytocin in Schizophrenia: Pathophysiology and Implications for Future Treatment

Schizophrenia is a form of mental disorder that is behaviorally characterized by abnormal behavior, such as social function deficits or other behaviors that are disconnected from reality. Dysregulation of oxytocin may play a role in regulating the expression of schizophrenia. Given oxytocin’s role in social cognition and behavior, a variety of studies have examined the potential clinical benefits of oxytocin in improving the psychopathology of patients with schizophrenia. In this review, we highlight the evidence for the role of endogenous oxytocin in schizophrenia, from animal models to human studies. We further discuss the potential of oxytocin as a therapeutic agent for schizophrenia and its implication in future treatment.

Brief mindfulness session improves mood and increases salivary oxytocin in psychology students

Mindfulness-based interventions (MBI) have been shown to be effective in increasing empathy in health professionals. Yet, more research is needed to analyse the specific influence of mindfulness exercises on biological variables involved in empathy, such as the biological system of oxytocin activity. In this study, we analyse the effects of a brief mindfulness session on positive and negative affect, state anxiety and salivary oxytocin (sOXT) in psychology students (N = 68). In the experimental group (n = 42), a mindfulness session was performed that included different guided meditation exercises. In the control group (n = 26), an emotion recognition exercise was carried out, along with a series of creative activities. Results showed that the mindfulness session was effective, because there was a significant reduction in negative affect (d = -.56, p < .001) and state anxiety (d = -.54, p = .007) in the experimental group. Likewise, there was an increase in sOXT (d = .99, p < .001) in this group, compared with the control group. Guided mindfulness meditation practice could be useful to reach an emotional and biological state that facilitates empathy. In this regard, the increase in sOXT after the mindfulness session adds further evidence about the biological mechanisms underlying the benefits of MBI on empathy.

Pharmacological treatment of eating disorders, comorbid mental health problems, malnutrition and physical health consequences

The pharmacological treatment of patients with an eating disorder (ED) often includes medications to treat their ED, comorbid mental health problems, malnutrition and the physical health problems resulting from it. The currently approved pharmacological treatment options for EDs are limited to fluoxetine for bulimia nervosa (BN) and - in some countries - lisdexamfetamine for binge eating disorder (BED). Thus, there are no approved pharmacological options for anorexia nervosa (AN), even though study results for olanzapine and dronabinol are promising. Topiramate might be an additional future option for the treatment of BN and BED. Selective serotonin reuptake inhibitors (SSRI), mirtazapine and bupropion could be considered for the treatment of comorbid unipolar depression. However, AN and BN are contraindications for bupropion. For ED patients with a manic episode, we recommend olanzapine in AN and risperidone in BN and BED; whereas for bipolar depression, olanzapine (plus fluoxetine) seems appropriate in AN and lamotrigine in BN and BED. Acute anxiety or suicidality may warrant benzodiazepine treatment with lorazepam. Proton-pump inhibitors, gastroprokinetic drugs, laxatives and hormones can alleviate certain physical health problems caused by EDs. Therapeutic drug monitoring, pharmacogenomic testing, a more restrictive use of "pro re nata" (PRN) medication, an interdisciplinary treatment approach, shared decision making (SDM) and the formulation of common treatment goals by the patients, their family or carers and clinicians could improve treatment success and safety. Novel genetic, immunological, microbiome and brain imaging research as well as new pharmacological developments like the use of psychedelics, stimulants, novel monoaminergic drugs, hormone analogues and drugs which enhance the effects of psychotherapy may extend our therapeutic options in the near future.

Oxytocin modulates responsibility attribution and hypothetical Resource allocation during cooperation

Reasonable responsibility attribution and resource allocation in intragroup contexts benefit the evolution of group cooperation. Oxytocin (OT) has been shown to promote prosocial behavior; however, it remains unclear whether OT affects responsibility attribution and hypothetical resource allocation. In the present study, participants were intranasally administered OT or placebo (PLC) before a response task with a partner. The participant could win a certain amount of money depending on the group's performance, which was determined by the faster player. The contribution was manipulated to be similar in the first phase, while the participants could individually contribute more in the second phase. Our results show that both groups attributed more credit to the player who performed better in a trial. Moreover, reward magnitude only enhanced effort-based attribution in the OT group. Although both groups proposed to distribute money based on individual efforts, the PLC group increased their effort-based allocation when they contributed more, regardless of the fact that the money was eventually equally distributed. Our study demonstrates that OT modulates responsibility attribution and hypothetical resource allocation in different manners, suggesting that OT has different effects on a participant's perception of individual contribution and fairness when allocating a reward during social cooperation in a real effort task.

Acute and Repeated Intranasal Oxytocin Differentially Modulate Brain-wide Functional Connectivity

Central release of the neuropeptide oxytocin (OXT) modulates neural substrates involved in socio-affective behavior. This property has prompted research into the use of intranasal OXT administration as an adjunctive therapy for brain conditions characterized by social impairment, such as autism spectrum disorders (ASD). However, the neural circuitry and brain-wide functional networks recruited by intranasal OXT administration remain elusive. Moreover, little is known of the neuroadaptive cascade triggered by long-term administration of this peptide at the network level. To address these questions, we applied fMRI-based circuit mapping in adult mice upon acute and repeated (seven-day) intranasal dosing of OXT. We report that acute and chronic OXT administration elicit comparable fMRI activity as assessed with cerebral blood volume mapping, but entail largely different patterns of brain-wide functional connectivity. Specifically, acute OXT administration focally boosted connectivity within key limbic components of the rodent social brain, whereas repeated dosing led to a prominent and widespread increase in functional connectivity, involving a strong coupling between the amygdala and extended cortical territories. Importantly, this connectional reconfiguration was accompanied by a paradoxical reduction in social interaction and communication in wild-type mice. Our results identify the network substrates engaged by exogenous OXT administration, and show that repeated OXT dosing leads to a substantial reconfiguration of brain-wide connectivity, entailing an aberrant functional coupling between cortico-limbic structures involved in socio-communicative and affective functions. Such divergent patterns of network connectivity might contribute to discrepant clinical findings involving acute or long-term OXT dosing in clinical populations.

Love is a physiological motivation (like hunger, thirst, sleep or sex)

The multitude of terms associated with love has given rise to a false perception of love. In this paper, only maternal and romantic love are considered. Love is usually regarded as a feeling, motivation, addiction, passion, and, above all, an emotion. This confusion has consequences in the lives of human beings, leading not only to divorces, suicides, femicides but possibly also to a number of mental illnesses and suffering. Therefore, it is crucial to first clarify what is meant by emotion, motivation and love. This work aims to finally place love within the category of physiological motivations, such as hunger, thirst, sleep, or sex, on the basis that love is also essential for human survival, especially in childhood. Love is presented from an evolutionary perspective. Some other similarities between love and other physiological motivations are pointed out, such as its importance for appropriate human development, both its ontogeny and its permanence, and the long-lasting consequences of abuse and neglect. There are summarized reasons that account for this, such as the fact that physiological motivations are essential for survival and that love is an essential motivation for the survival of human offspring. Other reasons are that minimum changes in the quantity and quality of love alters development, that there can be a variety of neurophysiological and behavioural states within a motivation, and that motivations (also love) appear and change throughout development. Also, motivations and love sometimes may lead to an addictive behaviour. Finally, it is recognized that once physiological motivations (and love) appear, they become permanent. In a third section, some potential social, cultural, clinical and scientific consequences of the proposed consideration of love as a motivation are discussed. Accordingly, love's recognition as a motivation in the clinical field would imply a better understanding of its disorders and its inclusion in classifications manuals such as The Diagnostic and Statistical Manual of Mental Disorders (DSM), or in the International Classification of Diseases (ICD). Considering love as a motivation rather than an emotion could also impact the results of scientific research (an example is included). A comprehensive understanding of these questions could potentially allow for a new therapeutic approach in the treatment of mental illness, while offering an all-inclusive evolutionary explanation of cultural phenomena such as the origin and diffusion of both language and art. Love should be understood as a physiological motivation, like hunger, sleep or sex, and not as an emotion as it is commonly considered.

Autism and psychosis as diametrical disorders of embodiment

Humans have evolved an elaborate system of self-consciousness, self-identity, self-agency, and self-embodiment that is grounded in specific neurological structures including an expanded insula. Instantiation of the bodily self has been most-extensively studied via the 'rubber hand illusion', whereby parallel stimulation of a hidden true hand, and a viewed false hand, leads to the felt belief that the false hand is one's own. Autism and schizophrenia have both long been regarded as conditions centrally involving altered development of the self, but they have yet to be compared directly with regard to the self and embodiment. Here, we synthesize the embodied cognition literature for these and related conditions, and describe evidence that these two sets of disorders exhibit opposite susceptibilities from typical individuals to the rubber hand illusion: reduced on the autism spectrum and increased in schizophrenia and other psychotic-affective conditions. Moreover, the opposite illusion effects are mediated by a consilient set of associated phenomena, including empathy, interoception, anorexia risk and phenotypes, and patterns of genetic correlation. Taken together, these findings: (i) support the diametric model of autism and psychotic-affective disorders, (ii) implicate the adaptive human system of self-embodiment, and its neural bases, in neurodevelopmental disorders, and suggest new therapies and (iii) experimentally ground Bayesian predictive coding models with regard to autism compared with psychosis. Lay summary: Humans have evolved a highly developed sense of self and perception of one's own body. The 'rubber hand illusion' can be used to test individual variation in sense of self, relative to connection with others. We show that this illusion is reduced in autism spectrum disorders, and increased in psychotic and mood disorders. These findings have important implications for understanding and treatment of mental disorders.

Oxytocin reduces neural activation in response to infant faces in nulliparous young women

Infant faces have distinctive features that together are described as baby schema, a configuration that facilitates caregiving motivation and behavior, and increases the perception of cuteness. In the current functional magnetic resonance imaging (fMRI) study, we investigated the effect of a within-subjects intranasal oxytocin administration (24 IU) and caregiving motivation on neural responses to infant faces of varying baby schema in 23 healthy nulliparous women. Overall, infant faces elicited activation in several brain regions involved in reward and salience processing, including the ventral tegmental area (VTA), putamen, amygdala, anterior cingulate cortex (ACC), and insula, and this activation was related to self-reported caregiving motivation. Critically, whereas we hypothesized enhanced neural caregiving-related responses after oxytocin administration, we observed reduced activation in the VTA, putamen and amygdala after oxytocin compared to placebo. In nulliparous women, oxytocin has been shown to reduce neural responses in the same regions in response to social stimuli using other paradigms. Oxytocin might affect neural activation toward social stimuli depending on elicited arousal and personal characteristics. The current study is the first to demonstrate this effect in response to infant faces and thereby adds to specify the role of oxytocin in human social information processing.