Reduced levels of vasopressin and reduced behavioral modulation of oxytocin in psychotic disorders

The Role of Oxytocin and Vasopressin in Attachment

Selective relationships and attachments are central to human health and well-being, both in current societies and during the course of evolution. The presence or absence of social bonds has consequences across the lifespan. The neurobiology of attachment is grounded in neuroendocrine substrates that are shared with reproduction and survival. Experimental studies of species, such as sheep or prairie voles, capable of showing selective social behaviors toward offspring or partners, have provided empirical evidence for the role of oxytocin and vasopressin in the formation of selective attachments. Developmental exposure to social experiences and to peptides, including oxytocin and vasopressin, also can "retune" the nervous system, altering thresholds for sociality, emotion regulation, and aggression. Without oxytocin and without the ability to form attachments the human brain as we know it could not exist. Knowledge of the neurobiology of attachment, and especially the role of oxytocin, also has implications for understanding both healthy behavior and treating mental disorders.

Measuring Oxytocin and Vasopressin: Bioassays, Immunoassays and Random Numbers

In this review, we consider the ways in which vasopressin and oxytocin have been measured since their first discovery. Two different ways of measuring oxytocin in widespread use currently give values in human plasma that differ by two orders of magnitude, and the values measured by these two methods in the same samples show no correlation. The notion that we should accept this seems absurd. Either one (or both) methods is not measuring oxytocin, or, by 'oxytocin', the scientists that use these different methods mean something very different. If these communities are to talk to each other, it is important to validate one method and invalidate the other, or else to establish exactly what each community understands by 'oxytocin'. A similar issue concerns vasopressin: again, different ways of measuring vasopressin give values in human plasma that differ by two orders of magnitude, and it appears that the same explanation for discrepant oxytocin measurements applies to discrepant vasopressin measurements. The first assays for oxytocin and vasopressin measured biological activity directly. When immunoassays were introduced, they encountered problems: high molecular weight factors in raw plasma interfered with the binding of antibodies to the hormones, leading to high and erroneous readings. When these interfering factors were removed by extraction of plasma samples, immunoassays gave measurements consistent with bioassays, with measures of turnover and with the sensitivity of target tissues to exogenous hormone. However, many recent papers use an enzyme-linked immunoassay to measure plasma levels without extracting the samples. Like the first radioimmunassays of unextracted plasma, this generates impossibly high and wholly erroneous measurements.

Comparing oxytocin and cortisol regulation in a double-blind, placebo-controlled, hydrocortisone challenge pilot study in children with autism and typical development

BACKGROUND

Children with autism spectrum disorder (ASD) show marked impairment in social functioning and poor adaptation to new and changing contexts, which may be influenced by underlying regulatory processes. Oxytocin (OT) and cortisol are key neuromodulators of biological and behavioral responses, show a synergistic effect, and have been implicated in the neuropathological profile in ASD. However, they are rarely investigated together. The purpose of the pilot study was to evaluate the relationship between cortisol and OT in children with ASD under baseline and physiological stress (hydrocortisone challenge) conditions. Arginine vasopressin (AVP), structurally similar to OT, was also examined.

METHODS

A double-blind, placebo-controlled, randomly assigned, crossover design was employed in 25 children 8-to-12 years with ASD (N = 14) or typical development (TD, N = 11). A low dose of hydrocortisone and placebo were administered via liquid suspension. Analysis of variance (ANOVA) was used to examine the within-subject factor "Condition" (hydrocortisone/placebo) and "Time" (pre and post) and the between-subject factor "Group" (ASD vs. TD). Pearson correlations examined the relationship between hormone levels and clinical profile.

RESULTS

There was a significant Time × Condition × Group interaction F (1.23) = 4.18, p = 0.05 showing a rise in OT during the experimental condition (hydrocortisone) and a drop during the placebo condition for the TD group but not the ASD group. There were no group differences for AVP. Hormone levels were associated with social profiles.

CONCLUSIONS

For the TD group, an inverse relationship was observed. OT increased during physiological challenge suggesting that OT played a stress-buffering role during cortisol administration. In contrast for the ASD group, OT remained unchanged or decreased during both the physiological challenge and the placebo condition, suggesting that OT failed to serve as a stress buffer under conditions of physiological stress. While OT has been tied to the social ability of children with ASD, the diminished moderating effect of OT on cortisol may also play a contributory role in the heightened stress often observed in children with ASD. These results contribute to our understanding of the growing complexity of the effects of OT on social behavior as well as the functional interplay and differential regulation OT may have on stress modulation.

Peripheral oxytocin and vasopressin: Biomarkers of psychiatric disorders? A comprehensive systematic review and preliminary meta-analysis

A large array of studies have investigated peripheral oxytocin (OT) and vasopressin (ADH) as potential biomarkers of psychiatric disorders, with highly conflicting and heterogenous findings. We searched Web of KnowledgeSM and Scopus® for English original articles investigating OT and/or ADH levels in different biological fluids (plasma/serum, saliva, urine and cerebrospinal fluid) across several psychiatric disorders. Sixty-four studies were included. We conducted 19 preliminary meta-analyses addressing OT alterations in plasma/serum, saliva, urine and cerebrospinal fluid of 7 psychiatric disorders and ADH alterations in plasma/serum, saliva, urine and cerebrospinal fluid of 6 psychiatric disorders compared to controls. Hedge's g was used as effect size measure, together with heterogeneity analyses, test of publication biases and quality control. None of them (except serum OT in anorexia nervosa) revealed significant differences. There is no convincing evidence that peripheral ADH or OT might be reliable biomarkers in psychiatric disorders. However, the lack of significant results was associated with high methodological heterogeneity, low quality of the studies, small sample size, and scarce reliability of the methods used in previous studies, which need to be validated and standardized.

Bridging the schism of schizophrenia through yoga-Review of putative mechanisms

Schizophrenia patients experience a 'disconnect' at multiple levels-neuronal networks, mental processes, and interpersonal relationships. The resultant poor quality-of-life and functional disability are related to the persistent cognitive deficits and negative symptoms, which are rather resistant to conventional antipsychotic medications. Yoga has emerged as an important therapeutic intervention to improve quality-of-life in schizophrenia. Recent preliminary evidence suggests that effects of yoga on cognitive and negative symptoms may drive this benefit. This study attempts to integrate evidence from neuroscience-based research, which focuses on the neuroplasticity-harnessing effects of yoga to bridge the schizophrenia connectopathy. In an overarching model to study putative neurobiological mechanisms that drive therapeutic effects of yoga, it is proposed that (a) various styles of meditation may help in strengthening the lateral and medial prefrontal brain networks, thus improving neurocognition and mentalizing abilities, and (b) learning and performing co-ordinated physical postures with a teacher facilitates imitation and the process of being imitated, which can improve social cognition and empathy through reinforcement of the premotor and parietal mirror neuron system. Oxytocin may play a role in mediating these processes, leading to better social connectedness and social outcomes. Clinical and heuristic implications of this model are further discussed.

Relationship of plasma oxytocin levels to baseline symptoms and symptom changes during three weeks of daily oxytocin administration in people with schizophrenia

Several clinical studies have found an inverse relationship between clinical symptoms and peripheral oxytocin (OT) levels in people with schizophrenia. As oxytocin is a putative treatment for schizophrenia, the effect of repeated dosing of OT on OT levels, clinical symptoms and the relationship between the two is of interest. In a, randomized, double blind, parallel group 3 week study (N=28) with daily administration of intranasal OT (20 IU twice daily) or placebo (PBO), we examined the effect of OT administration on the correlation between the change in peripheral OT levels and change in clinical symptoms in patients with schizophrenia. At baseline, there were no significant treatment group differences in OT levels. There were no significant associations between baseline OT levels and any symptom measures. After 3 weeks of OT/PBO dosing, there was no significant difference in the magnitude of change in OT levels between the two treatment groups. Correlations between changes in peripheral OT levels and changes in the BPRS total and negative symptom scores were not different between treatment groups. Larger studies are needed to examine the effect of exogenous OT on peripheral OT levels and the relationship between the latter and clinical symptoms. Clinical Trials.gov=NCT00884897.

Antipsychotic drug-like facilitation of latent inhibition by a brain-penetrating neurotensin-1 receptor agonist

Latent inhibition (LI) is a measure of cognitive gating and refers to reduced conditioned learning when there is pre-exposure to the conditioned stimulus (CS) before it is paired with the unconditioned stimulus (US). Dysregulation of LI is associated with some neuropsychiatric disorders, including schizophrenia, and the ability to facilitate LI in rodents is a reasonably good predictive test for antipsychotic drugs. Converging evidence supports neurotensin-1 receptor (NTS1) agonists as novel drugs for schizophrenia. Therefore, we investigated the ability of a brain-penetrating, selective NTS1 agonist, PD149163, to facilitate LI in heterozygous Brattleboro rats, a strain that exhibits naturally low LI. Conditioned taste aversion to flavored water (FW; 0.1% saccharin) was induced by pairing it with malaise-inducing injections of lithium chloride (LiCl). Prior to LiCl-FW pairing, rats received subcutaneous injections of saline, or PD149163 (100 µg/kg or 200 µg/kg). Half the rats in each drug group had been allowed to drink FW the day before the LiCl-FW pairing (pre-exposed rats). Two days after pairing, the amount of FW each rat consumed was recorded. LI, defined as significantly greater FW drinking in the pre-exposed group compared with the non pre-exposed group, was exhibited only among rats that received 200 µg/kg of PD149163. These results further support NTS1 agonists as potentially novel drugs for the treatment of schizophrenia.

Potential of Oxytocin in the Treatment of Schizophrenia

Schizophrenia is a heterogeneous, debilitating disorder characterized by three distinct sets of clinical features: positive symptoms, negative symptoms, and cognitive deficits. Extant antipsychotic drugs have been most successful at treating the positive symptoms of patients with schizophrenia but have minimal therapeutic effects on negative symptoms and cognitive deficits, which are the symptoms that best predict the poor prognosis of these patients. Therefore, there has been a major effort towards identifying compounds that alleviate these symptoms. Oxytocin (OT) is a nonapeptide that regulates peripheral reproductive-relevant functions, and also acts as a neurotransmitter in the brain. Converging evidence from both preclinical and clinical research suggests that OT may have therapeutic efficacy for the positive symptoms, negative symptoms, and cognitive deficits of schizophrenia. In the majority of the small, randomized, placebo-controlled clinical trials conducted to date, OT has shown particular promise in its potential to treat the intractable negative symptoms and social cognitive deficits exhibited by most of the patients with this debilitating disorder. In this leading article, we summarize the clinical evidence relevant to (1) endogenous OT and schizophrenia, and (2) the putative therapeutic effects of OT on each of the three clinical domains.

Atypical Social Development in Vasopressin-Deficient Brattleboro Rats

Over the past 3 decades, a large body of evidence has accumulated demonstrating that the neuropeptide arginine vasopressin (AVP) plays a critical role in regulating social behavior. The overwhelming majority of this evidence comes from adults, leaving a gap in our understanding of the role of AVP during development. Here, we investigated the effect of chronic AVP deficiency on a suite of juvenile social behaviors using Brattleboro rats, which lack AVP due to a mutation in the Avp gene. Social play behavior, huddling, social investigation & allogrooming, and ultrasonic vocalizations (USVs) of male and female rats homozygous for the Brattleboro mutation (Hom) were compared with their wild-type (WT) and heterozygous (Het) littermates during same-sex, same-genotype social interactions. Male and female Hom juveniles exhibited less social play than their Het and WT littermates throughout the rise, peak, and decline of the developmental profile of play. Hom juveniles also emitted fewer prosocial 50 kHz USVs, and spectrotemporal characteristics (call frequency and call duration) of individual call types differed from those of WT and Het juveniles. However, huddling behavior was increased in Hom juveniles, and social investigation and 22 kHz USVs did not differ across genotypes, demonstrating that not all social interactions were affected in the same manner. Collectively, these data suggest that the Avp gene plays a critical role in juvenile social development.

Intranasal Oxytocin: Myths and Delusions

Despite widespread reports that intranasal application of oxytocin has a variety of behavioral effects, very little of the huge amounts applied intranasally appears to reach the cerebrospinal fluid. However, peripheral concentrations are increased to supraphysiologic levels, with likely effects on diverse targets including the gastrointestinal tract, heart, and reproductive tract. The wish to believe in the effectiveness of intranasal oxytocin appears to be widespread and needs to be guarded against with scepticism and rigor. Preregistering trials, declaring primary and secondary outcomes in advance, specifying the statistical methods to be applied, and making all data openly available should minimize problems of publication bias and questionable post hoc analyses. Effects of intranasal oxytocin also need proper dose-response studies, and such studies need to include control subjects for peripheral effects, by administering oxytocin peripherally and by blocking peripheral actions with antagonists. Reports in the literature of oxytocin measurements include many that have been made with discredited methodology. Claims that peripheral measurements of oxytocin reflect central release are questionable at best.

Oxytocin, Vasopressin, and the Motivational Forces that Drive Social Behaviors

The motivation to engage in social behaviors is influenced by past experience and internal state, but also depends on the behavior of other animals. Across species, the oxytocin (Oxt) and vasopressin (Avp) systems have consistently been linked to the modulation of motivated social behaviors. However, how they interact with other systems, such as the mesolimbic dopamine system, remains understudied. Further, while the neurobiological mechanisms that regulate prosocial/cooperative behaviors have been extensively examined, far less is understood about competitive behaviors, particularly in females. In this chapter, we highlight the specific contributions of Oxt and Avp to several cooperative and competitive behaviors and discuss their relevance to the concept of social motivation across species, including humans. Further, we discuss the implications for neuropsychiatric diseases and suggest future areas of investigation.

Sex and diagnosis specific associations between DNA methylation of the oxytocin receptor gene with emotion processing and temporal-limbic and prefrontal brain volumes in psychotic disorders

BACKGROUND

The oxytocin (OT) system, including receptor epigenetic mechanisms, has been shown to influence emotion processing, especially in females. Whether OT receptor (OXTR) epigenetic alterations occur across psychotic disorders in relation to illness-related disturbances in social cognition and brain anatomy is unknown.

METHODS

Participants with affective and nonaffective psychotic disorders (92 women, 75 men) and healthy controls (38 women, 37 men) from the Chicago site of the BSNIP study completed the Penn Emotion Recognition Test (ER-40), a facial emotion recognition task. We measured cytosine methylation at site -934 upstream of the OXTR start codon in DNA from whole blood, and for the first time their relationship with plasma OT levels assessed by enzyme-immunoassay. Volumes of brain regions supporting social cognition were measured from MRI scans using FreeSurfer.

RESULTS

Patients with prototypic schizophrenia features showed higher levels of DNA methylation than those with prototypic bipolar features. Methylation was higher in women than men, and was associated with poorer emotion recognition only in female patients and controls. Greater methylation was associated with smaller volumes in temporal-limbic and prefrontal regions associated previously with social cognition, but only in healthy women and females with schizophrenia.

CONCLUSION

DNA methylation of the OXTR site -934 was higher in schizophrenia spectrum than bipolar patients. Among patients, it was linked to behavioral deficits in social cognition and neuroanatomic structures known to support emotion processing only in schizophrenia spectrum individuals.

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.

Cerebrospinal fluid and plasma oxytocin concentrations are positively correlated and negatively predict anxiety in children

The neuropeptide oxytocin (OXT) exerts anxiolytic and prosocial effects in the central nervous system of rodents. A number of recent studies have attempted to translate these findings by investigating the relationships between peripheral (e.g., blood, urinary and salivary) OXT concentrations and behavioral functioning in humans. Although peripheral samples are easy to obtain in humans, whether peripheral OXT measures are functionally related to central OXT activity remains unclear. To investigate a possible relationship, we quantified OXT concentrations in concomitantly collected cerebrospinal fluid (CSF) and blood samples from child and adult patients undergoing clinically indicated lumbar punctures or other CSF-related procedures. Anxiety scores were obtained in a subset of child participants whose parents completed psychometric assessments. Findings from this study indicate that plasma OXT concentrations significantly and positively predict CSF OXT concentrations (r=0.56, P=0.0064, N=27). Moreover, both plasma (r=-0.92, P=0.0262, N=10) and CSF (r=-0.91, P=0.0335, N=10) OXT concentrations significantly and negatively predicted trait anxiety scores, consistent with the preclinical literature. Importantly, plasma OXT concentrations significantly and positively (r=0.96, P=0.0115, N=10) predicted CSF OXT concentrations in the subset of child participants who provided behavioral data. This study provides the first empirical support for the use of blood measures of OXT as a surrogate for central OXT activity, validated in the context of behavioral functioning. These preliminary findings also suggest that impaired OXT signaling may be a biomarker of anxiety in humans, and a potential target for therapeutic development in individuals with anxiety disorders.

The promise of biological markers for treatment response in first-episode psychosis: a systematic review

Successful treatment of first-episode psychosis is one of the major factors that impacts long-term prognosis. Currently, there are no satisfactory biological markers (biomarkers) to predict which patients with a first-episode psychosis will respond to which treatment. In addition, a non-negligible rate of patients does not respond to any treatment or may develop side effects that affect adherence to the treatments as well as negatively impact physical health. Thus, there clearly is a pressing need for defining biomarkers that may be helpful to predict response to treatment and sensitivity to side effects in first-episode psychosis. The present systematic review provides (1) trials that assessed biological markers associated with antipsychotic response or side effects in first-episode psychosis and (2) potential biomarkers associated with biological disturbances that may guide the choice of conventional treatments or the prescription of innovative treatments. Trials including first-episode psychoses are few in number. Most of the available data focused on pharmacogenetics markers with so far only preliminary results. To date, these studies yielded-beside markers for metabolism of antipsychotics-no or only a few biomarkers for response or side effects, none of which have been implemented in daily clinical practice. Other biomarkers exploring immunoinflammatory, oxidative, and hormonal disturbances emerged as biomarkers of first-episode psychoses in the last decades, and some of them have been associated with treatment response. In addition to pharmacogenetics, further efforts should focus on the association of emergent biomarkers with conventional treatments or with innovative therapies efficacy, where some preliminary data suggest promising results.

Plasma oxytocin explains individual differences in neural substrates of social perception

The neuropeptide oxytocin plays a critical role in social cognition and behavior. A number of studies using intranasal administration have demonstrated that oxytocin improves social perception. However, little is known about the relationship between individual differences in endogenous levels of oxytocin and social cognition. In the current study, we assessed the relationship between endogenous oxytocin and brain activity during an animacy perception paradigm. Thirty-seven male participants underwent scanning and provided a blood sample for oxytocin analysis. In line with previous research, perception of animacy was associated with activations in superior temporal sulcus, inferior frontal gyrus, and medial prefrontal cortex (mPFC). Notably, participants’ levels of plasma oxytocin robustly predicted activation in areas critical for social cognitive processes, such that higher oxytocin levels were related to increased activity in dorsal mPFC, ventral mPFC, dorsolateral PFC, superior temporal gyrus, and temporoparietal junction (TPJ), suggesting differential processing of social stimuli. Together these results show that stable variations in endogenous oxytocin levels explain individual differences in social perception.

Plasma oxytocin levels predict social cue recognition in individuals with schizophrenia

Lower endogenous levels of the neuropeptide oxytocin may be an important biological predictor of social cognition impairments in schizophrenia (SZ). Prior studies have demonstrated that lower-level social cognitive processes (e.g., facial affect perception) are significantly associated with reduced plasma oxytocin levels in SZ; however, it is unclear whether higher-level social cognition, which requires inferential processes and knowledge not directly presented in the stimulus, is associated with endogenous oxytocin. The current study explored the association between endogenous oxytocin levels and lower- and higher-level social cognition in 40 individuals diagnosed with SZ and 22 demographically matched healthy controls (CN). All participants received the Social Cue Recognition Test (SCRT), which presents participants with videotaped interpersonal vignettes and subsequent true/false questions related to concrete or abstract aspects of social interactions in the vignettes. Results indicated that SZ had significantly higher plasma oxytocin concentrations than CN. SZ and CN did not differ on SCRT hits, but SZ had more false positives and lower sensitivity scores than CN. Higher plasma oxytocin levels were associated with better sensitivity scores for abstract items in CN and fewer false positives for concrete items in individuals with SZ. Findings indicate that endogenous oxytocin levels predict accurate encoding of lower-level socially relevant information in SZ.

Plasma oxytocin levels predict olfactory identification and negative symptoms in individuals with schizophrenia

Basic neuroscience research provides strong evidence for the role of oxytocin in olfactory processes and social affiliation in rodents. Given prior indication of olfactory impairments that are linked to greater severity of asociality in schizophrenia, we examined the association between plasma oxytocin levels and measures of olfaction and social outcome in a sample of outpatients with schizophrenia (n=39) and demographically matched healthy controls (n=21). Participants completed the 40-item University of Pennsylvania Smell Identification Test (UPSIT), and rated each odor for how positive and how negative it made them feel. Results indicated that individuals with schizophrenia had higher plasma oxytocin levels and lower overall accuracy for UPSIT items than controls. Individuals with schizophrenia also reported experiencing more negative emotionality than controls in response to the olfactory stimuli. Lower plasma oxytocin levels were associated with poorer accuracy for pleasant and unpleasant odors and greater severity of asociality in individuals with schizophrenia. These findings suggest that endogenous oxytocin levels may be an important predictor of olfactory identification deficits and negative symptoms in schizophrenia.

Oxytocin, testosterone, and human social cognition

I describe an integrative social-evolutionary model for the adaptive significance of the human oxytocinergic system. The model is based on a role for this hormone in the generation and maintenance of social familiarity and affiliation across five homologous, functionally similar, and sequentially co-opted contexts: mothers with offspring, female and male mates, kin groups, individuals with reciprocity partners, and individuals within cooperating and competing social groups defined by culture. In each situation, oxytocin motivates, mediates and rewards the cognitive and behavioural processes that underlie the formation and dynamics of a more or less stable social group, and promotes a relationship between two or more individuals. Such relationships may be positive (eliciting neurological reward, reducing anxiety and thus indicating fitness-enhancing effects), or negative (increasing anxiety and distress, and thus motivating attempts to alleviate a problematic, fitness-reducing social situation). I also present evidence that testosterone exhibits opposite effects from oxytocin on diverse aspects of cognition and behaviour, most generally by favouring self-oriented, asocial and antisocial behaviours. I apply this model for effects of oxytocin and testosterone to understanding human psychological disorders centrally involving social behaviour. Reduced oxytocin and higher testosterone levels have been associated with under-developed social cognition, especially in autism. By contrast, some combination of oxytocin increased above normal levels, and lower testosterone, has been reported in a notable number of studies of schizophrenia, bipolar disorder and depression, and, in some cases, higher oxytocin involves maladaptively 'hyper-developed' social cognition in these conditions. This pattern of findings suggests that human social cognition and behaviour are structured, in part, by joint and opposing effects of oxytocin and testosterone, and that extremes of such joint effects partially mediate risks and phenotypes of autism and psychotic-affective conditions. These considerations have direct implications for the development of therapies for alleviating disorders of social cognition, and for understanding how such disorders are associated with the evolution of human cognitive-affective architecture.

Association between Genetic Variation in the Oxytocin Receptor Gene and Emotional Withdrawal, but not between Oxytocin Pathway Genes and Diagnosis in Psychotic Disorders

Social dysfunction is common in patients with psychotic disorders. Oxytocin is a neuropeptide with a central role in social behavior. This study aims to explore the relationship between oxytocin pathway genes and symptoms related to social dysfunction in patients with psychotic disorders. We performed association analyses between four oxytocin pathway genes (OXT, OXTR, AVP, and CD38) and four areas of social behavior-related psychopathology as measured by Positive and Negative Syndrome Scale. For this purpose, we used both a polygenic risk score (PGRS) and single OXTR candidate single nucleotide polymorphism previously reported in the literature (rs53576, rs237902, and rs2254298). A total of 734 subjects with DSM-IV psychotic spectrum disorders and 420 healthy controls were included. Oxytocin pathway PGRSs were calculated based on the independent Psychiatric Genomics Consortium study sample. There was a significant association between symptom of Emotional Withdrawal and the previously reported OXTR risk allele A in rs53576. No significant associations between oxytocin pathway gene variants and a diagnosis of psychotic disorder were found. Our findings indicate that while oxytocin pathway genes do not appear to contribute to the susceptibility to psychotic disorders, variations in the OXTR gene might play a role in the development of impaired social behavior.

Changes in social functioning and circulating oxytocin and vasopressin following the migration to a new country

Prior studies have reported associations between plasma oxytocin and vasopressin and markers of social functioning. However, because most human studies have used cross-sectional designs, it is unclear whether plasma oxytocin and vasopressin influences social functioning or whether social functioning modulates the production and peripheral release of these peptides. In order to address this question, we followed individuals who experienced major changes in social functioning subsequent to the migration to a new country. In this study, 59 new international students were recruited shortly after arrival in the host country and reassessed 2 and 5 months later. At each assessment participants provided information on their current social functioning and blood samples for oxytocin and vasopressin analysis. Results indicated that changes in social functioning were not related to changes in plasma oxytocin. Instead, baseline oxytocin predicted changes in social relationship satisfaction, social support, and loneliness over time. In contrast, plasma vasopressin changed as a function of social integration. Baseline vasopressin was not related to changes in social functioning over time. These results emphasize the different roles of plasma oxytocin and vasopressin in responses to changes in social functioning in humans.