Association between oxytocin receptor gene polymorphisms and self-rated 'empathic concern' in schizophrenia

The impact of childhood trauma exposure on social functioning in schizophrenia: the moderated mediation role of oxytocin and oxytocin receptor gene polymorphisms

BACKGROUND

Childhood trauma has been linked to increased risk of schizophrenia and social dysfunction, and oxytocin and its receptor gene have been implicated in regulating social behavior. This study investigated the potential role of oxytocin and oxytocin receptor gene (OXTR) in mediating the effects of childhood trauma on social functioning in schizophrenia.

METHODS

The study consisted of 382 patients with schizophrenia and 178 healthy controls who were assessed using the Taiwanese version of the Childhood Trauma Questionnaire (CTQ-SF), the Social Functioning Scale (SFS), and plasma oxytocin levels. DNA was extracted to genotype the OXTR and ten single-nucleotide polymorphisms (SNPs; rs2254298, rs237885, rs237887, rs237899, rs53576, rs9840864, rs13316193, rs7632287, rs1042778, and rs237895) were selected.

RESULTS

Patients with schizophrenia showed higher CTQ-SF scores (t = 12.549, p < 0.001), lower SFS scores (t = -46.951, p < 0.001), and lower plasma oxytocin levels (t = -5.448, p < 0.001) compared to healthy controls. The study also found significant differences in OXTR SNPs between both groups, with risk alleles being more prevalent in patients with schizophrenia (t = 2.734, p = 0.006). Results indicated a significant moderated mediation effect, with oxytocin and the OXTR SNPs partially mediating the relationship between childhood trauma exposure and social functioning in patients with schizophrenia (index of mediation = 0.038, 95% CI [0.033-0.044]).

CONCLUSIONS

The findings suggest that oxytocin and its receptor gene may be promising targets for interventions aimed at improving social functioning in patients with a history of childhood trauma and schizophrenia. However, further research is needed to fully understand these effects and the potential of oxytocin-based interventions in this population.

OXTR polymorphisms associated with severity and treatment responses of schizophrenia

The mechanisms generating specific symptoms of schizophrenia remain unclear and genetic research makes it possible to explore these issues at a fundamental level. Taking into account the associations between the oxytocin system and social functions, which are apparently impaired in schizophrenia patients, we hypothesized that the oxytocin receptor gene (OXTR) might be associated with schizophrenia symptoms in both severity and responses to antipsychotics and did this exploratory positional study. A total of 2363 patients with schizophrenia (1181 males and 1182 females) included in our study were randomly allocated to seven antipsychotic treatment groups and received antipsychotic monotherapy for 6 weeks. Their blood DNA was genotyped for OXTR polymorphisms. Their symptom severity was assessed by Positive and Negative Syndrome Scale (PANSS), and the scores were transformed into seven factors (positive, disorganized, negative symptoms apathy/avolition, negative symptoms deficit of expression, hostility, anxiety and depression). Percentage changes in PANSS scores from baseline to week 6 were calculated to quantify antipsychotic responses. We found that OXTR polymorphisms were nominally associated with the severity of overall symptoms (rs237899, β = 1.669, p = 0.019), hostility symptoms (rs237899, β = 0.427, p = 0.044) and anxiety symptoms (rs13316193, β = -0.197, p = 0.038). As for treatment responses, OXTR polymorphisms were nominally associated with the improvement in negative symptoms apathy/avolition (rs2268490, β = 2.235, p = 0.0499). No association between severity or response to treatment and OXTR polymorphisms was found with statistical correction for multiplicity. Overall, our results highlighted the possibility of nominally significant associations of the OXTR gene with the severity and improvement in schizophrenia symptoms. Given the exploratory nature of this study, these associations are indicative of the role of the OXTR gene in the pathology of schizophrenia and may contribute to further elucidate the mechanism of specific symptoms of schizophrenia and to exploit antipsychotics more effective to specific symptoms.

Overlap between genetic variants associated with schizophrenia spectrum disorders and intelligence quotient: a systematic review

BACKGROUND

To study whether there is genetic overlap underlying the risk for schizophrenia spectrum disorders (SSDs) and low intelligence quotient (IQ), we reviewed and summarized the evidence on genetic variants associated with both traits.

METHODS

We performed this review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and preregistered it in PROSPERO. We searched the Medline databases via PubMed, PsycInfo, Web of Science and Scopus. We included studies in adults with a diagnosis of SSD that explored genetic variants (single nucleotide polymorphisms [SNPs], copy number variants [CNVs], genomic insertions or genomic deletions), estimated IQ and studied the relationship between genetic variability and both traits (SSD and IQ). We synthesized the results and assessed risk of bias using the Quality of Genetic Association Studies (Q-Genie) tool.

RESULTS

Fifty-five studies met the inclusion criteria (45 case-control, 9 cross-sectional, 1 cohort), of which 55% reported significant associations for genetic variants involved in IQ and SSD. The SNPs more frequently explored through candidate gene studies were in COMT, DTNBP1, BDNF and TCF4. Through genome-wide association studies, 2 SNPs in CHD7 and GATAD2A were associated with IQ in patients with SSD. The studies on CNVs suggested significant associations between structural variants and low IQ in patients with SSD.

LIMITATIONS

Overall, primary studies used heterogeneous IQ measurement tools and had small samples. Grey literature was not screened.

CONCLUSION

Genetic overlap between SSD and IQ supports the neurodevelopmental hypothesis of schizophrenia. Most of the risk polymorphisms identified were in genes relevant to brain development, neural proliferation and differentiation, and synaptic plasticity.

Upper cortical layer-driven network impairment in schizophrenia

Schizophrenia is one of the most widespread and complex mental disorders. To characterize the impact of schizophrenia, we performed single-nucleus RNA sequencing (snRNA-seq) of >220,000 neurons from the dorsolateral prefrontal cortex of patients with schizophrenia and matched controls. In addition, >115,000 neurons were analyzed topographically by immunohistochemistry. Compositional analysis of snRNA-seq data revealed a reduction in abundance of GABAergic neurons and a concomitant increase in principal neurons, most pronounced for upper cortical layer subtypes, which was substantiated by histological analysis. Many neuronal subtypes showed extensive transcriptomic changes, the most marked in upper-layer GABAergic neurons, including down-regulation in energy metabolism and up-regulation in neurotransmission. Transcription factor network analysis demonstrated a developmental origin of transcriptomic changes. Last, Visium spatial transcriptomics further corroborated upper-layer neuron vulnerability in schizophrenia. Overall, our results point toward general network impairment within upper cortical layers as a core substrate associated with schizophrenia symptomatology.

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.

[Associations between the oxytocinergic system genes, perinatal complications and interpersonal relationships in patients with schizophrenia]

OBJECTIVE

To search for the associations between genes of the oxytocinergic pathway and psychosocial functioning in schizophrenia, namely, the ability of schizophrenic patients to form interpersonal relationships, taking into account the influence of such an environmental factor as perinatal complications.

MATERIAL AND METHODS

The study included 383 people (140 women and 243 men, mean age 32.6±11.4 years), of whom 107 had a history of perinatal complications, and 276 did not. Psychosocial functioning was assessed using the Personal and social relationships domain of The Personal and Social Performance scale (PSP). Polymorphisms rs53576, rs4686302, rs1042778 in the oxytocin receptor gene (OXTR) and polymorphism rs3796863 in the transmembrane glycoprotein (CD38) gene were genotyped.

RESULTS

There is the association between the OXTR rs53576 polymorphism and scores on the interpersonal relations domain (p=0.005). Significant differences are found between carriers of the GG genotype and carriers of the A allele (p=0.003). In the group without perinatal complications, the genotype does not have a significant effect on PSP score. There are no associations between other polymorphisms and the level of interpersonal relationships in any of the studied groups.

CONCLUSION

The results are in accordance with the notions accepted on the basis of numerous evidences that link the genes of the oxytocinergic system with social behavior. We obtained new data on the influence of the known polymorphism OXTR rs53576 on the phenotype, which has not been studied previously in this aspect - the ability to form interpersonal relationships in patients with schizophrenia, while it was shown that the effect of the genotype depends on the environmental risk factor (perinatal complications).

Empathy and Hormonal Changes as Predictors of Sensitive Responsiveness towards Infant Crying: A Study Protocol

Sensitive responsiveness refers to parents' ability to recognize and respond to infants' cues and has been linked to parental empathy. Additionally, oxytocin (OT) and vasopressin (AVP) are hormones important for sensitivity and empathy. The aim of this study is to test the links between dispositional empathy along with changing OT and AVP levels and responsiveness to a life-like doll in couples and to verify whether these factors are predictors of responsiveness to a child's cues. Exploratory analyses include predictors of sensitive responsiveness: polymorphisms of OXTR, AVPR1a and CD38 genes, personal characteristics and relational factors. The project employs standardized experimental settings that can be used with non-parents and the assessment of parental sensitive responsiveness towards their child. The participants are couples expecting their first child (111) and childless couples (110). The procedure involves caretaking of a life-like doll. Salivary samples and questionnaire data are collected in a planned manner. In the second part, the expectant couples are invited for the assessment of their sensitivity to their own child (Free Play episodes). Parental sensitivity is assessed using the Ainsworth Sensitivity Scale. This paper presents an interdisciplinary research project that reaches beyond the questionnaire measurement, considering many factors influencing the dynamics of adult-infant interaction.

The influence of rs53576 polymorphism in the oxytocin receptor (OXTR) gene on empathy in healthy adults by subtype and ethnicity: a systematic review and meta-analysis

Empathy is essential for navigating complex social environments. Prior work has shown associations between rs53576, a single nucleotide polymorphism (SNP) located in the oxytocin receptor gene (OXTR), and generalized empathy. We undertook a systematic review and meta-analysis to assess the effects of rs53576 on subdomains of empathy, specifically cognitive empathy (CE) and affective empathy (AE), in healthy adults. Twenty cohorts of 8933 participants aged 18-98 were identified, including data from the Sydney Memory and Ageing Study, a cohort of older community adults. Meta-analyses found G homozygotes had greater generalized empathic abilities only in young to middle-aged adults. While meta-analyses of empathy subdomains yielded no significant overall effects, there were differential effects based on ethnicity. G homozygotes were associated with greater CE abilities in Asian cohorts (standardized mean difference; SMD: 0.09 [2.8·10^-3-0.18]), and greater AE performance in European cohorts [SMD: 0.12 (0.04-0.21)]. The current literature highlights a need for further work that distinguishes between genetic and ethnocultural effects and explores effects of advanced age on this relationship.

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.

Polygenic risk for autism spectrum disorder affects left amygdala activity and negative emotion in schizophrenia

Although the diagnoses based on phenomenology have many practical advantages, accumulating evidence shows that schizophrenia and autism spectrum disorder (ASD) share some overlap in genetics and clinical presentation. It remains largely unknown how ASD-associated polygenetic risk contributes to the pathogenesis of schizophrenia. In the present study, we calculated high-resolution ASD polygenic risk scores (ASD PRSs) and selected optimal ten ASD PRS with minimal P values in the association analysis of PRSs, with schizophrenia to assess the effect of ASD PRS on brain neural activity in schizophrenia cases and controls. We found that amplitude of low-frequency fluctuation in left amygdala was positively associated with ASD PRSs in our cohort. Correlation analysis of ASD PRSs with facial emotion recognition test identified the negative correlation of ASD PRSs with negative emotions in schizophrenia cases and controls. Finally, functional enrichment analysis of PRS genes revealed that neural system function and development, as well as signal transduction, were mainly enriched in PRS genes. Our results provide empirical evidence that polygenic risk for ASD contributes to schizophrenia by the intermediate phenotypes of left amygdala function and emotion recognition. It provides a promising strategy to understand the relationship between phenotypes and genotypes shared in mental disorders.

Reduced DNA Methylation of the Oxytocin Receptor Gene Is Associated With Anhedonia-Asociality in Women With Recent-Onset Schizophrenia and Ultra-high Risk for Psychosis

Negative symptoms are recognized as a fundamental feature of schizophrenia throughout the disease course. Epigenetic alterations in the oxytocin receptor gene (OXTR) may be a key mechanism involved in social-emotional disturbances of schizophrenia. Here, we investigated OXTR methylation and its association with clinical and brain network connectivity phenotypes of negative symptoms, particularly anhedonia-asociality, in individuals with recent-onset schizophrenia (ROS) and at ultrahigh risk (UHR) for psychosis. Sixty-four ROS (39 women), 46 UHR (19 women), and 98 healthy individuals (52 women) participated in this study. OXTR methylation was quantified using the pyrosequencing method. A subset of participants (16 ROS, 23 UHR, and 33 healthy controls [HCs]) underwent a 5.5-minute resting-state functional magnetic resonance imaging to determine the relationship between OXTR methylation and the striatal-amygdala network functional connectivity (FC) underlying anhedonia-asociality. Both men and women with ROS and UHR showed significantly decreased OXTR methylation compared to HCs. In women with ROS and UHR, decreased OXTR methylation showed a significant correlation with increased anhedonia-asociality. FC of the striatal-amygdala network, positively associated with the severity of anhedonia-asociality, showed an inverse correlation with OXTR methylation. This study suggests that epigenetic alterations of OXTR, which can be detected before the development of full-blown psychosis, confer susceptibility to schizophrenia and play a crucial role in the manifestation of anhedonia-asociality, particularly in women.

What Do You Have in Mind? Measures to Assess Mental State Reasoning in Neuropsychiatric Populations

Social interaction is closely associated with both functional capacity and well-being. Previous research has not only revealed evidence of social dysfunction in individuals with a wide range of psychiatric and neurological disorders but also generated an abundance of potential measures for assessing social cognition. This review explores the most popular measures used within neuropsychiatric populations to investigate the ability to recognize or reason about the mental states of others. Measures are also critically analyzed in terms of strengths and limitations to aid task selection in future clinical studies. The most frequently applied assessment tools use verbal, visual or audiovisual forms of presentation and assess recognition of mental states from facial features, self-rated empathy, the understanding of other's cognitive mental states such as beliefs and intentions, or the ability to combine knowledge of other's thoughts and emotions in order to understand subtle communications or socially inappropriate behavior. Key weaknesses of previous research include limited investigation of relationships with clinical symptoms, and underutilization of measures of everyday social functioning that offer a useful counterpart to traditional "lab" tasks. Future studies should aim to carefully select measures not only based on the range of skills to be assessed but also taking into account potential difficulties with interpretation and the need to gain insight into the application of social cognitive skills as well as ability per se. Some of the best measures include those with well-matched control trials (e.g., Yoni Task) or those that restrict the influence of verbal deficits (e.g., intentions comic strip task), elicit spontaneous mentalizing (e.g., Animations Task), and possess greater ecological validity (e.g., Movie for the Assessment of Social Cognition). Social cognitive research within psychiatric populations will be further enhanced through the development of more closely matched control tasks, and the exploration of relationships between task performance, medication, strategy use, and broader emotional and motor functions.

OXTR rs53576 polymorphism impacts interpersonal adaptability: Dispositional forgiveness as a mediator

Polymorphisms in the oxytocin receptor (OXTR) gene have been shown to be related to individual differences in social skills that are important for building and maintaining social relationships, such as the capability to efficiently process social information and regulate emotions. However, what remains unclear is the potential roles of OXTR polymorphisms in interpersonal adaptability, namely the ability to cope with the situational demands of interpersonal interactions. In this study, we examined the roles of OXTR rs53576 polymorphism in interpersonal adaptability, empathic perception, and dispositional forgiveness in a cohort of 573 college freshmen. The results indicated that the scores on interpersonal adaptability and dispositional forgiveness, apart from empathic perception, increased as functions of the number of G alleles of OXTR rs53576. Moreover, dispositional forgiveness, but not empathic perception, mediated the association between OXTR rs53576 and interpersonal adaptability. The findings highlight the influences of the OXTR gene on adaptive interpersonal interactions, especially when individuals face changing social situations.

Co-shared genetics and possible risk gene pathway partially explain the comorbidity of schizophrenia, major depressive disorder, type 2 diabetes, and metabolic syndrome

Schizophrenia (SCZ) and major depressive disorder (MDD) in treatment-naive patients are associated with increased risk for type 2 diabetes (T2D) and metabolic syndrome (MetS). SCZ, MDD, T2D, and MetS are often comorbid and their comorbidity increases cardiovascular risk: Some risk genes are likely co-shared by them. For instance, transcription factor 7-like 2 (TCF7L2) and proteasome 26S subunit, non-ATPase 9 (PSMD9) are two genes independently reported as contributing to T2D and SCZ, and PSMD9 to MDD as well. However, there are scarce data on the shared genetic risk among SCZ, MDD, T2D, and/or MetS. Here, we briefly describe T2D, MetS, SCZ, and MDD and their genetic architecture. Next, we report separately about the comorbidity of SCZ and MDD with T2D and MetS, and their respective genetic overlap. We propose a novel hypothesis that genes of the prolactin (PRL)-pathway may be implicated in the comorbidity of these disorders. The inherited predisposition of patients with SCZ and MDD to psychoneuroendocrine dysfunction may confer increased risk of T2D and MetS. We illustrate a strategy to identify risk variants in each disorder and in their comorbid psychoneuroendocrine and mental-metabolic dysfunctions, advocating for studies of genetically homogeneous and phenotype-rich families. The results will guide future studies of the shared predisposition and molecular genetics of new homogeneous endophenotypes of SCZ, MDD, and metabolic impairment.

[Oxytocin in schizophrenia : Evidence for an etiological and therapeutic relevance of the social neuromodulator]

Neurobiological results from animal models as well as biochemical and genetic findings in patients indicate that the oxytocin (OT) system may be dysfunctional in schizophrenia. On this pathogenetic basis transnasally administered OT (tnOT) could be an innovative treatment option for schizophrenia. Experimental data from animal studies are also suggestive of a particular effectiveness in treatment-resistant schizophrenia. To date, clinical data on tnOT treatment of schizophrenia patients does not unequivocally support a general therapeutic effect on the psychopathology but suggests positive effects on higher integrated social cognitive performance, such as empathy and mentalization. In particular, tnOT augmentation of a social cognitive skills training resulted in a marked and lasting treatment effect; however, numerous person- and context-dependent variables can potentially moderate individual effects of OT and may even reverse effects in certain constellations. Most clinical studies so far have not systematically accounted and controlled for these factors with the probable result of larger variance of recorded treatment effects and lower likelihood of ascertaining positive effectiveness. Furthermore, there is still a gap of knowledge on dose response relations and central nervous system (CNS) permeation in man following tnOT administration. This review aims to give a concise overview on the evidence for the etiological relevance of the neurohormone OT and its treatment potential in schizophrenia.

Metacognition, Personal Distress, and Performance-Based Empathy in Schizophrenia

BACKGROUND

People with schizophrenia experience significant deficits in the kinds of empathic skills that are the foundation for interpersonal relationships. Researchers have speculated that deficits in empathic skills in schizophrenia may be related to disturbances in metacognition and heightened levels of personal distress. To explore this issue, this study examined whether better metacognition and reduced personal distress would be associated with improved performance on cognitive and affective empathy tasks. Further, we tested whether metacognition moderated the relationship between personal distress and empathy.

METHOD

Fifty-eight participants with schizophrenia-spectrum disorders receiving community-based treatment completed a self-report questionnaire of personal distress, a performance-based measure of empathy, and an observer-rated interview to assess metacognitive capacity.

RESULTS

Correlation analyses revealed that metacognitive capacity, but not personal distress, was significantly associated with cognitive and affective empathy performance. Moderation results suggest the relationship between personal distress and affective empathy performance was significant for those with low metacognition, but that the relationship was the opposite of hypotheses-increased personal distress predicted better performance. This relationship changed at higher levels of metacognition, when increased personal distress became associated with reduced performance.

CONCLUSIONS

This study is the first of its kind to examine performance-based empathy with metacognition and personal distress. Results suggest interventions targeted to improve metacognition may be useful in enhancing empathic skills.

Associations between Oxytocin Receptor Gene Polymorphisms, Empathy towards Animals and Implicit Associations towards Animals

Oxytocin has been well researched in association with psychological variables and is widely accepted as a key modulator of human social behaviour. Previous work indicates involvement of oxytocin receptor gene (OXTR) single nucleotide polymorphisms (SNPs) in human-human empathy, however little is known about associations of OXTR SNPs with empathy and affective reactions of humans towards animals. Five OXTR SNPs previously found to associate with human social behaviour were genotyped in 161 students. Empathy towards animals and implicit associations were evaluated. A General Linear Model was used to investigate the OXTR alleles and allelic combinations along with socio-demographic variables and their influence on empathy towards animals. Empathy towards animals showed a significant association with OXTR SNP rs2254298; homozygous G individuals reported higher levels of empathy towards animals than heterozygous (GA). Our preliminary findings show, for the first time, that between allelic variation in OXTR and animal directed empathy in humans maybe associated, suggesting that OXTRs social behaviour role crosses species boundaries, warranting independent replication.

Oxytocin-related single-nucleotide polymorphisms, family environment, and psychopathic traits

Multiple studies have linked oxytocin to social behavior and affiliation-attachment. This research would suggest that oxytocin function may relate to the absence of loving kindness and empathy in psychopathy. The current study examined the associations between 3 oxytocin-related single-nucleotide polymorphisms (SNPs), participant-reported invalidating childhood environment, and psychopathic traits in community adults, predicting that alleles associated with higher empathy in the literature would relate to lower levels of psychopathic affective traits in particular. Results showed that the rs53576 SNP on the oxytocin receptor and cumulative risk alleles across the 3 SNPs were associated with psychopathic traits, and the interaction between cumulative risk and an emotionally invalidating environment was associated especially with affective deficits of psychopathy. Although this study requires replication in larger samples, results lend support to the role of attachment-related processes in psychopathy. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Rare missense coding variants in oxytocin receptor (OXTR) in schizophrenia cases are associated with early trauma exposure, cognition and emotional processing

BACKGROUND

Oxytocin is a peptide hormone that influences the integration of social cognition with behavior and affect regulation. Oxytocin also prominently directs the transition of neuronal GABA neurotransmission from excitatory to inhibitory after birth. The oxytocin receptor (OXTR) is linked to schizophrenia, a heterogeneous syndrome. Relationships of OXTR polymorphisms with specific clinical features could aid in evaluating any role of oxytocin in the pathogenesis of schizophrenia.

METHOD

Schizophrenia cases with rare missense coding OXTR single nucleotide variants (SNVs) were identified from a well-characterized sample of cases and controls who were assessed for symptoms, cognition and early life trauma.

RESULTS

Five of 48 cases showed rare OXTR variants. Compared to the other cases they had less severe negative symptoms (deficits in emotional expression and motivation) and less severe general psychopathology scores (depression and anxiety). They demonstrated lower nonverbal (performance) than verbal intelligence due to deficient perceptual organization and slow processing speed. They also reported greater early trauma exposure (physical and sexual abuse and emotional trauma).

CONCLUSION

Cases carrying rare OXTR SNVs had less negative and affective symptoms than other cases, but similar psychotic symptoms, along with specific cognitive deficits. The clinical characterization of these cases occurred in association with environmental exposure to early trauma, especially sexual abuse, which may have influenced the expression of schizophrenia in subjects harboring specific SNVs in the OXTR.

Adversity impacting on oxytocin and behaviour: timing matters

The endogenous oxytocin system plays a vital role in facilitating parturition, lactation and social interaction in humans and other mammals. It also impacts on a number of important endocrine, immune and neurotransmitter systems. A well-regulated oxytocin system has been proposed to increase resilience, and therefore reduce the likelihood of an individual developing mental illness or substance dependence. This review discusses the adverse external influences that can modulate oxytocin receptor and protein levels and impact on substance use and mental health. The paper highlights the impact of adversity such as poor maternal care, parental substance use and child abuse or neglect. We review clinical and preclinical data on the impact of adversity on the basis of the time of exposure from infancy and early childhood, to adolescence, adulthood to older age. Previous research suggests that dysregulation of the endogenous oxytocin system may be implicated in determining susceptibility to stress, anxiety, addiction and mental health conditions. The impact of external influence seems to be strongest in specific time periods where the system shows experience-based development or natural fluctuations in oxytocin levels. Interventions that target the oxytocin system during or soon after exposure to adversity may prove protective.

The Importance of Social Cognition in Improving Functional Outcomes in Schizophrenia

Social cognition has become recognized as an important driver of functional outcomes and overall recovery in patients with schizophrenia, mediating the relationship between neurocognition and social functioning. Since antipsychotic therapy targeting remission of clinical symptoms has been shown to have a limited impact on social cognition, there has been an increasing drive to develop therapeutic strategies to specifically improve social cognition in schizophrenia. We sought to review current evidence relating to social cognition in schizophrenia and its clinical implications, including interventions designed to target the core domains of social cognition (emotion processing, theory of mind, attributional bias, and social perception) as a means of improving functional outcomes and thereby increasing the likelihood of recovery. Relevant articles were identified by conducting a literature search in PubMed using the search terms "schizophrenia" AND "cognition" AND "social functioning," limited to Title/Abstract, over a time period of the past 10 years. Current evidence demonstrates that schizophrenia is associated with impairments in all four core domains of social cognition, during the pre-first-episode, first-episode, early, and chronic phases of the disease, and that such impairments are important determinants of functional outcome. Interventions targeting the four core domains of social cognition comprise psychosocial approaches (social cognition training programs) and pharmacological therapies. Social cognition training programs targeting multiple and specific core domains of social cognition have shown promise in improving social cognition skills, which, in some cases, has translated into improvements in functional outcomes. Use of some psychosocial interventions has additionally resulted in improvements in clinical symptoms and/or quality of life. Pharmacological therapies, including oxytocin and certain antipsychotics, have yielded more mixed results, due in part to the confounding impact of factors including variation in receptor genetics, bioavailability, pharmacokinetics, and drug-drug interactions, and inconsistencies between study designs and medication dosages. Additional research is required to advance our understanding of the role of social cognition in schizophrenia, and to further establish the utility of targeted interventions in this setting.

Transactions Between Substance Use Intervention, the Oxytocin Receptor (OXTR) Gene, and Peer Substance Use Predicting Youth Alcohol Use

This study investigated the oxytocin receptor (OXTR) gene's moderation of associations between exposure to a substance misuse intervention, average peer substance use, and adolescents' own alcohol use during the 9th-grade. OXTR genetic risk was measured using five single nucleotide polymorphisms (SNPs), and peer substance use was based on youths' nominated closest friends' own reports of alcohol, cigarette, and marijuana use, based on data from the PROSPER project. Regression models revealed several findings. First, low OXTR risk was linked to affiliating with friends who reported less substance use in the intervention condition but not the control condition. Second, affiliating with high substance-using friends predicted youth alcohol risk regardless of OXTR risk or intervention condition. Third, although high OXTR risk youth in the intervention condition who associated with low substance-using friends reported somewhat higher alcohol use than comparable youth in the control group, the absolute level of alcohol use among these youth was still among the lowest in the sample.

The role of oxytocin in the pathogenesis and treatment of schizophrenia

Introduction: Until recently, oxytocin was mainly associated with the pathophysiology of childbirth and sexual functions, but lately this hormone has become the object of interest to psychiatry and psychology due to the significant influence of oxytocin on human behavior in the field of social and emotional functioning. Current scientific research focuses on the participation of oxytocin in the pathogenesis and therapy of mental disorders.

Aim: The aim of the paper is to present, on the basis of available literature, the significance of oxytocin for various psychological functions, with particular emphasis on the influence of oxytocin on the course and clinical picture of schizophrenia.

Method: Available articles from the Medline / PubMed database were analyzed, which were searched using keywords: oxytocin, schizophrenia, therapeutic use of oxytocin, social cognition, positive symptoms, negative symptoms and time descriptors: 2013-2017. There are included articles published in Polish and English.

Results:The research results carried out so far suggest that oxytocin plays a significant role in modulating complex socio-emotional behaviors in schizophrenic patients. The existing research results also indicate a relationship between the dysregulation of the oxytocinergic system and the pathophysiology of schizophrenia. Many of the studies prove that there is a relationship between the level of oxytocin in the patients' blood plasma and the severity of the disease symptoms. Recent genetic studies indicate a possible relationship between polymorphism of oxytocin genesand polymorphism of oxytocin receptor genes and the risk of developing schizophrenia.

Conclusions: Contemporary research on the therapeutic potential of oxytocin and its influence on the functioning of schizophrenia patients seem to be very promising and may contribute to increasing the effectiveness of treatment of schizophrenia and possibly other mental disorders, which in turn will improve the quality of life of patients in cognitive, social and emotional functioning.

Oxytocin receptor gene polymorphisms exert a modulating effect on the onset age in patients with obsessive-compulsive disorder

The oxytocin receptor (OXTR) is a potential candidate in the pathophysiology of obsessive-compulsive disorder (OCD). The present study investigated the association between common single-nucleotide polymorphism (SNPs) of the OXTR gene and the affected status of OCD or distinct clinical subtypes of OCD including the age at onset and symptom dimensions. Ten SNPs of OXTR were examined in 615 patients with OCD and 581 healthy controls. Single-marker and haplotype-based association analyses were conducted. While OXTR variants were not associated with the affected status of OCD or its clinical symptom dimensions, rs2268493 (p=0.00185) and rs13316193 (p=0.00461) of the OXTR gene were associated with the age at onset in patients with OCD. In addition, in haplotype-based association analyses, there was a significant association between the OXTR gene and the onset age in patients with OCD. In particular, the G-C-G haplotype of rs2268493-rs2254298-rs11316193 and the T-G-A haplotype of rs237887-rs2268490-rs4686301 were positively associated with late-onset OCD. Our results suggest that common variants of OXTR may exert a modulating effect on the onset age in OCD pathophysiology. The potential involvement of the oxytocin system in the development and expression of OCD warrants further longitudinal research.

Epigenetic correlates of neonatal contact in humans

Animal models of early postnatal mother–infant interactions have highlighted the importance of tactile contact for biobehavioral outcomes via the modification of DNA methylation (DNAm). The role of normative variation in contact in early human development has yet to be explored. In an effort to translate the animal work on tactile contact to humans, we applied a naturalistic daily diary strategy to assess the link between maternal contact with infants and epigenetic signatures in children 4–5 years later, with respect to multiple levels of child-level factors, including genetic variation and infant distress. We first investigated DNAm at four candidate genes: the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), μ-opioid receptor M1 (OPRM1) and oxytocin receptor (OXTR; related to the neurobiology of social bonds), and brain-derived neurotrophic factor (BDNF; involved in postnatal plasticity). Although no candidate gene DNAm sites significantly associated with early postnatal contact, when we next examined DNAm across the genome, differentially methylated regions were identified between high and low contact groups. Using a different application of epigenomic information, we also quantified epigenetic age, and report that for infants who received low contact from caregivers, greater infant distress was associated with younger epigenetic age. These results suggested that early postnatal contact has lasting associations with child biology.

The effects of adjunctive intranasal oxytocin in patients with schizophrenia

OBJECTIVES

Both human and animal studies have suggested that oxytocin may have therapeutic potential in the treatment of schizophrenia. We evaluated the effects of intranasal oxytocin on cognition and its predictive factors in Japanese patients with schizophrenia.

METHODS

Subjects were 16 chronic schizophrenia patients who underwent intranasal oxytocin treatment for 3 months and were assessed for changes in severity of clinical symptoms and cognitions. Fifteen of the 16 subjects underwent 3-Tesla magnetic resonance imaging.

RESULTS

Oxytocin significantly reduced scores on the positive and negative syndrome scale, especially on the negative symptoms. As for cognition, there was an improvement of the verbal fluency. Furthermore, the change of the negative score in positive and negative syndrome scale showed a negative correlation with the gray matter volumes of the right insula and left cingulate cortex.

CONCLUSIONS

Our results indicate that daily administration of intranasal oxytocin may be effective for ameliorating clinical symptoms and cognitive functions in chronic schizophrenia patients, and this improvement may be related to the gray matter volume of the right insula and left cingulate cortex.

Cumulative Risk on the Oxytocin Receptor Gene (OXTR) Predicts Empathic Communication by Physician Assistant Students

In the relationship between patients and health care providers, few communicative features are as significant as the providers' ability to express empathy. A robust empirical literature describes the importance of physician communication skills-particularly those that convey empathy-yet few studies have examined empathic communication by physician assistants, who provide primary care for an increasing number of Americans. The present study examines the empathic communication of physician assistant students in interactions with standardized patients. Over a 6-month period, each student conducted three clinical interviews, each of which was evaluated for empathic communication by the patients, the students' clinical instructors, and third-party observers. Students also provided saliva samples for genotyping six single-nucleotide polymorphisms on the oxytocin receptor gene (OXTR) that are linked empirically to empathic behavior. Consistent with recent research, this study adopted a cumulative risk approach wherein students were scored for their number of risky alleles on the single-nucleotide polymorphisms. Results indicated that cumulative risk on OXTR receptor gene predicted lower patient empathy scores as rated by instructors and observers, but not by standardized patients.

The role of stress-regulation genes in moderating the association of stress and daily-life psychotic experiences

OBJECTIVE

The interaction of single nucleotide polymorphisms with both distal and proximal environmental factors across the extended psychosis phenotype is understudied. This study examined (i) the interaction of relevant SNPs with both early-life adversity and proximal (momentary) stress on psychotic experiences (PEs) in an extended psychosis sample; and (ii) differences between early-psychosis and non-clinical groups for these interactions.

METHODS

Two hundred and forty-two non-clinical and 96 early-psychosis participants were prompted randomly eight times daily for 1 week to complete assessments of current experiences, including PEs and stress. Participants also reported on childhood trauma and were genotyped for 10 SNPs on COMT, RGS4, BDNF, FKBP5, and OXTR genes.

RESULTS

Unlike genetic variants, distal and proximal stressors were associated with PEs in both samples and were more strongly associated with PEs in the early-psychosis than in the non-clinical group. The RGS4 TA and FKBP5 CATT haplotypes interacted with distal stress, whereas the A allele of OXTR (rs2254298) interacted with proximal stress, increasing momentary levels of PEs in the early-psychosis group. No interactions emerged with COMT or BDNF variants.

CONCLUSION

Individual differences in relevant stress-regulation systems interact with both distal and proximal psychosocial stressors in shaping the daily-life manifestation of PEs across the psychosis continuum.

Revisiting the impact of OXTR rs53576 on empathy: A population-based study and a meta-analysis

Oxytocin in the brain is related to empathy, which refers to the ability to understand and share others' internal states or responses. Previous studies have investigated the impact of OXTR rs53576, the most intensively examined polymorphism in the oxytocin receptor (OXTR) gene, on individual differences in empathy. However, these studies produced inconsistent results. In the current study, we reexamined the association of OXTR rs53576 with empathy in a relatively large population (N=1830) and also evaluated the association by a comprehensive meta-analysis (N=6631, 13 independent samples). The replication study indicated that OXTR rs53576 was indeed associated with individual differences in empathy. Individuals with a greater number of G alleles showed better empathic ability, particularly in fantasizing other's feelings and actions. The meta-analysis not only confirmed this association, but also indicated that the impact of this polymorphism was significant in both Europeans and Asians. These findings provide convincing evidence for the impact of OXTR rs53576 on empathy, highlighting the importance of OXTR gene in individuals' social cognition.

Empathy in schizophrenia: A meta-analysis of the Interpersonal Reactivity Index

Empathy is a complex construct, thought to contain multiple components. One popular measurement paradigm, the Interpersonal Reactivity Index (IRI), has been used extensively to measure empathic tendencies in schizophrenia research across four domains: empathic concern, perspective-taking, personal distress, and fantasy. However, no recent meta-analysis has been conducted for all four factors of this scale. The goal of this meta-analysis was to examine self-reported empathic tendencies for each factor of the IRI in people with schizophrenia as compared to healthy controls. A literature search revealed 32 eligible schizophrenia studies. The Hedges' g standardized difference effect size was calculated for each component using a random effects meta-analytic model. Compared to healthy controls, schizophrenia samples reported significantly reduced tendencies for empathic concern, perspective-taking, and fantasy, but significantly greater tendencies for personal distress. Duration of illness significantly moderated the results for perspective-taking such that those with a longer duration exhibited greater deficits; percent female significantly moderated the results for personal distress such that samples with more females exhibited reduced effect sizes. Future work is needed to examine the impact of heightened personal distress on the empathic tendencies and abilities of those with schizophrenia, including the possible role of emotion regulation.

Relationship of a common OXTR gene variant to brain structure and default mode network function in healthy humans

A large body of research suggests that oxytocin receptor (OXTR) gene polymorphisms may influence both social behaviors and psychiatric conditions related to social deficits, such as autism spectrum disorders (ASDs), schizophrenia, and mood and anxiety disorders. However, the neural mechanism underlying these associations is still unclear. Relative to controls, patients with these psychiatric conditions show differences in brain structure, and in resting state fMRI (rs-fMRI) signal synchronicity among default mode network (DMN) regions (also known as functional connectivity). We used a stepwise imaging genetics approach in 328 healthy young adults to test the hypothesis that 10 SNPs in OXTR are associated with differences in DMN synchronicity and structure of some of the associated brain regions. As OXTR effects may be sex-dependent, we also tested whether our findings were modulated by sex. OXTR rs2254298 A allele carriers had significantly lower rsFC with PCC in a cluster extending from the right fronto-insular cortex to the putamen and globus pallidus, and in bilateral dorsal anterior cingulate cortex (dACC) compared to individuals with the GG genotype; all observed effects were found only in males. Moreover, compared to the male individuals with GG genotype ofrs2254298, the male A allele carriers demonstrated significantly thinner cortical gray matter in the bilateral dACC. Our findings suggest that there may be sexually dimorphic mechanisms by which a naturally occurring variation of the OXTR gene may influence brain structure and function in DMN-related regions implicated in neuropsychiatric disorders.

Contribution of oxytocin receptor polymorphisms to amygdala activation in schizophrenia spectrum disorders

BACKGROUND

Oxytocin has been proposed to mediate amygdala dysfunction associated with altered emotion processing in schizophrenia, but the contribution of oxytocin pathway genes is yet to be investigated.

AIMS

To identify potential different contributions of three oxytocin receptor polymorphisms (rs53576, rs237902 and rs2254298) between patients with schizophrenia spectrum disorders (SCZ), affective spectrum disorders (AD) and healthy controls (HC).

METHOD

In a total of 346 participants (104 with SCZ, 100 with AD, and 142 HC) underwent genotyping and functional magnetic resonance imaging (fMRI) during an emotional faces matching paradigm. Genetic association analyses were performed to test the possible effects on task-induced BOLD amygdala response to fearful/angry faces.

RESULTS

In participants with SCZ, the rs237902 G allele was associated with low amygdala activation (left hemisphere: b=-4.99, Bonferroni corrected P=0.04) and interaction analyses showed that this association was disorder specific (left hemisphere: Bonferroni corrected P=0.003; right hemisphere: Bonferroni corrected P=0.03). There were no associations between oxytocin polymorphisms and amygdala activation in the total sample, among AD patients or HC.

CONCLUSIONS

Rs237902 was associated with amygdala activation in response to fearful/angry faces only in patients with SCZ. Our findings indicate that the endogenous oxytocin system could serve as a contributing factor in biological underpinnings of emotion processing and that this contribution is disorder specific.

DECLARATION OF INTEREST

O.A.A. received speaker's honoraria from GSK, Otsuka, Lundbeck.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Congenital prosopagnosia is associated with a genetic variation in the oxytocin receptor (OXTR) gene: An exploratory study

Face-recognition deficits, referred to with the term prosopagnosia (i.e., face blindness), may manifest during development in the absence of any brain injury (from here the term congenital prosopagnosia, CP). It has been estimated that approximately 2.5% of the population is affected by face-processing deficits not depending on brain lesions, and varying a lot in severity. The genetic bases of this disorder are not known. In this study we tested for genetic association between single-nucleotide polymorphisms (SNPs) in the oxytocin receptor gene (OXTR) and CP in a restricted cohort of Italian participants. We found evidence of an association between the common genetic variants rs53576 and rs2254298 OXTR SNPs and prosopagnosia. This association was also found when including an additional group of German individuals classified as prosopagnosic in the analysis. Our preliminary data provide initial support for the involvement of genetic variants of OXTR in a relevant cognitive impairment, whose genetic bases are still largely unexplored.

Affective empathy in schizophrenia: a meta-analysis

BACKGROUND

Affective empathy, or the emotional response one has to the experiences or emotional states of others, contributes to relationship-maintaining behaviors and is key in fostering social connections, yet no work has synthesized the body of literature for people with schizophrenia. The aim of the present meta-analysis was to determine the extent to which those diagnosed with schizophrenia experience deficits in affective empathy.

METHODS

A literature search was conducted of studies examining empathy. Data were analyzed using a random effects meta-analytic model with Hedges' g standardized mean difference effect size.

RESULTS

Individuals with schizophrenia exhibited significant, medium deficits in affective empathy (k=37). Measurement type moderated the affective empathy deficit such that performance-based measures showed larger schizophrenia group deficits than self-report measures.

CONCLUSION

Consistent, significant deficits in affective empathy were found comparing people with schizophrenia to healthy controls, especially when using performance-based assessments. The medium effect suggests an important role for empathy in the realm of social cognitive research, and points to the need for further investigation of measurement techniques and associations with functional outcomes.

Association of a Common Oxytocin Receptor Gene Polymorphism with Self-Reported 'Empathic Concern' in a Large Population of Healthy Volunteers

Background

Previous research has linked genomic variations of the oxytocin receptor (OXTR) gene with individual differences in empathy. The impact of these variations on specific cognitive and emotional aspects of empathy, however, remains to be clarified.

Methods

We analysed associations of a common OXTR polymorphism (rs53576) with trait empathy in a sample of 421 blood donors (231 M, 190 F; age 18–74) using the Interpersonal Reactivity Index (IRI) as an established multidimensional self-report measure of empathy.

Results

Female sex was significantly associated with higher empathy scores in all IRI scales (p<0.001) with the exception of the cognitive perspective taking scale (p = 0.09). The overall trait empathy score was significantly associated with rs53576 (p = 0.01), with mean scores increasing from AA to GG genotypes. An analysis of the IRI subscores revealed that the polymorphism was especially associated with the emotional empathic concern scale (p = 0.02). Separate analysis of the male and female subgroup revealed a significant association of the polymorphism with female (p = 0.04), but not with male (p = 0.20) empathic concern. A comparison of effect sizes between the groups showed greater effects for women compared to men although effect size differences did not become significant in our sample.

Conclusions

Our findings suggest a significant association of the rs53576 OXTR gene polymorphism with trait empathy and especially with emotional aspects of empathy. This association is possibly weaker or absent in men compared to women.

Oxytocin and parent-child interaction in the development of empathy among children at risk for autism

This longitudinal study investigated whether variation in the oxytocin receptor gene (OXTR) and early parent-child interactions predicted later empathic behavior in 84 toddlers at high or low familial risk for autism spectrum disorder. Two well-studied OXTR single-nucleotide polymorphisms, rs53576 and rs2254298, were examined. Parent-child interaction was measured at 15 and 18 months of age during free play sessions. Empathy was measured at 24 and 30 months using a response to parental distress paradigm. While there was no direct association between parent-child interaction quality or OXTR and empathy, rs53576 moderated the relation between interaction quality and empathy. Results suggest that the interplay between OXTR and early parent-child interactions predicts individual differences in empathy in children at varying risk for atypical social development. Findings are consonant with a differential susceptibility model in which an OXTR variant may increase the social salience of interaction processes for specific allele carriers. These results increase our understanding of predictors of empathy development in young children with a wide range of social outcomes. (PsycINFO Database Record

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.

BDNF Val66Met Polymorphism Is Associated with Self-Reported Empathy

Empathy is an important driver of human social behaviors and presents genetic roots that have been studied in neuroimaging using the intermediate phenotype approach. Notably, the Val66Met polymorphism of the Brain-derived neurotrophic factor (BDNF) gene has been identified as a potential target in neuroimaging studies based on its influence on emotion perception and social cognition, but its impact on self-reported empathy has never been documented. Using a neurogenetic approach, we investigated the association between the BDNF Val66Met polymorphism and self-reported empathy (Davis' Interpersonal Reactivity Index; IRI) in a sample of 110 young adults. Our results indicate that the BDNF genotype is significantly associated with the linear combination of the four facets of the IRI, one of the most widely used self-reported empathy questionnaire. Crucially, the effect of BDNF Val66Met goes beyond the variance explained by two polymorphisms of the oxytocin transporter gene previously associated with empathy and its neural underpinnings (OXTR rs53576 and rs2254298). These results represent the first evidence suggesting a link between the BDNF gene and self-reported empathy and warrant further studies of this polymorphism due to its potential clinical significance.

Oxytocin Pathway Genes: Evolutionary Ancient System Impacting on Human Affiliation, Sociality, and Psychopathology

Oxytocin (OT), a nonapeptide signaling molecule originating from an ancestral peptide, appears in different variants across all vertebrate and several invertebrate species. Throughout animal evolution, neuropeptidergic signaling has been adapted by organisms for regulating response to rapidly changing environments. The family of OT-like molecules affects both peripheral tissues implicated in reproduction, homeostasis, and energy balance, as well as neuromodulation of social behavior, stress regulation, and associative learning in species ranging from nematodes to humans. After describing the OT-signaling pathway, we review research on the three genes most extensively studied in humans: the OT receptor (OXTR), the structural gene for OT (OXT/neurophysin-I), and CD38. Consistent with the notion that sociality should be studied from the perspective of social life at the species level, we address human social functions in relation to OT-pathway genes, including parenting, empathy, and using social relationships to manage stress. We then describe associations between OT-pathway genes with psychopathologies involving social dysfunctions such as autism, depression, or schizophrenia. Human research particularly underscored the involvement of two OXTR single nucleotide polymorphisms (rs53576, rs2254298) with fewer studies focusing on other OXTR (rs7632287, rs1042778, rs2268494, rs2268490), OXT (rs2740210, rs4813627, rs4813625), and CD38 (rs3796863, rs6449197) single nucleotide polymorphisms. Overall, studies provide evidence for the involvement of OT-pathway genes in human social functions but also suggest that factors such as gender, culture, and early environment often confound attempts to replicate first findings. We conclude by discussing epigenetics, conceptual implications within an evolutionary perspective, and future directions, especially the need to refine phenotypes, carefully characterize early environments, and integrate observations of social behavior across ecological contexts.

Lack of Association between Oxytocin Receptor (OXTR) Gene Polymorphisms and Alexithymia: Evidence from Patients with Obsessive-Compulsive Disorder

Oxytocin receptor gene single nucleotide polymorphisms have been associated with structural and functional alterations in brain regions, which involve social-emotional processing. Therefore, oxytocin receptor gene polymorphisms may contribute to individual differences in alexithymia, which is considered to be a dysfunction of emotional processing. The aim of this study was to evaluate the association between oxytocin receptor gene single nucleotide polymorphisms or haplotypes and alexithymia in patients with obsessive-compulsive disorder. We recruited 355 patients with obsessive-compulsive disorder (234 men, 121 women). Alexithymia was measured by using the Toronto Alexithymia Scale. We performed single-marker and haplotype association analyses with eight single nucleotide polymorphisms (rs237885, rs237887, rs2268490, rs4686301, rs2254298, rs13316193, rs53576, and rs2268498) in the oxytocin receptor gene. There were no significant associations between any of the eight single nucleotide polymorphism of the oxytocin receptor gene and alexithymia. In addition, a six-locus haplotype block (rs237885-rs237887-rs2268490-rs4686301-rs2254298-rs13316193) was not significantly associated with alexithymia. These findings suggest that genetic variations in the oxytocin receptor gene may not explain a significant part of alexithymia in patients with obsessive-compulsive disorder.

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.

The CD38 genotype (rs1800561 (4693C>T): R140W) is associated with an increased risk of admission to the neonatal intensive care unit

BACKGROUNDS

Preterm birth (PTB)/admission to the neonatal intensive care unit (NICU) is a complex disorder associated with significant neonatal mortality and morbidity and long-term adverse health consequences. Multiple lines of evidence suggest that genetic factors play an important role in its etiology.

AIM

Given the role of CD38 in term delivery through oxytocin (OXT) release, we hypothesized that OXT signaling may play a role in the etiology of PTB/admission to the NICU. This study was designed to identify genetic variation in the CD38-oxytocin pathway associated with PTB/admission to the NICU.

METHODS

To identify common genetic variants predisposing individuals to PTB/admission to the NICU, we genotyped two single nucleotide polymorphisms (SNPs) in the CD38-oxytocin pathway in 63 case mothers, 55 control mothers, and 188 female volunteers in Nara Medical University Hospital, Japan.

RESULTS

Maternal genetic effect analysis of the SNP genotype data revealed a significant association between an SNP in CD38 (rs1800561 (4693C>T): R140W), which was reported to be correlated with diabetes and autism, and the risk of NICU admission. On the other hand, an SNP in the oxytocin receptor (OXTR) (rs2254298) showed no correlation with the risk of NICU admission.

CONCLUSION

Our study points to an association between maternal common polymorphisms in the CD38 (rs1800561) gene in Japanese women and susceptibility to PTB/admission to the NICU. Future studies with larger sample sizes are needed to confirm the findings of this study.

The many faces of oxytocin: implications for psychiatry

Oxytocin is known as the 'love hormone' due its role in promoting mother-child and pair bonding. More recent research indicates that oxytocin may have broader pro-social effects on behavior and cognition, which points towards oxytocin's potential as an agent to help improve social cognition and functioning in psychiatric disorders such as schizophrenia and autism. However, new research on oxytocin has also uncovered a 'darker side', including oxytocin's possible role in social out-grouping and envy. Instead of a simple view of oxytocin as 'good' or 'bad', a more accurate depiction of oxytocin's role in social processing likely involves the presence of moderating factors. We review moderation effects in oxytocin and their implications for psychiatry. One implication is that, across diagnostic categories, oxytocin administration may have positive effects for patients with social cognitive deficits but negative effects for patients with social cognitive bias. We conclude that future intervention studies should use methods such as signal detection to measure both deficit and bias parameters of social cognition and to evaluate potential individual and contextual moderators both within and between psychiatric diagnoses in order to determine for whom oxytocin treatment may be beneficial and for whom it may actually be harmful.

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.

Oxytocin receptor and vasopressin receptor 1a genes are respectively associated with emotional and cognitive empathy

Empathy is the ability to recognize and share in the emotions of others. It can be considered a multifaceted concept with cognitive and emotional aspects. Little is known regarding the underlying neurochemistry of empathy and in the current study we used a neurogenetic approach to explore possible brain neurotransmitter pathways contributing to cognitive and emotional empathy. Both the oxytocin receptor (OXTR) and the arginine vasopressin receptor 1a (AVPR1a) genes contribute to social cognition in both animals and humans and hence are prominent candidates for contributing to empathy. The following research examined the associations between polymorphisms in these two genes and individual differences in emotional and cognitive empathy in a sample of 367 young adults. Intriguingly, we found that emotional empathy was associated solely with OXTR, whereas cognitive empathy was associated solely with AVPR1a. Moreover, no interaction was observed between the two genes and measures of empathy. The current findings contribute to our understanding of the distinct neurogenetic pathways involved in cognitive and emotional empathy and underscore the pervasive role of both oxytocin and vasopressin in modulating human emotions.

The role of oxytocin in empathy to the pain of conflictual out-group members among patients with schizophrenia

BACKGROUND

Oxytocin (OT) is associated with our ability to empathize and has been shown to play a major role in mediating social behaviors within the context of intergroup dynamics. Schizophrenia is associated with impaired empathy, and with a dysfunctional oxytocinergic system. The effect of OT on the empathic responses of patients with schizophrenia within the context of intergroup relationships has not been studied. The present study examined the effect of OT on the patients' empathic responses to pain experienced by in-group, conflictual out-group and neutral out-group members.

METHOD

In a double-blind, placebo-controlled, within-subject cross-over design, the responses on the Pain Evaluation Task of 28 male patients with schizophrenia were compared to 27 healthy male controls. All participants received a single intranasal dose of 24 IU OT or placebo, 1 week apart.

RESULTS

OT induced an empathy bias in the healthy controls towards the conflictual out-group members. Although this effect was absent in the patient group, OT seems to heighten an empathic bias in the patient group towards the in-group members when rating non-painful stimuli.

CONCLUSIONS

The study demonstrates that the administration of OT can result in empathic bias towards adversary out-group members in healthy controls but not in patients with schizophrenia. However, the OT-induced bias in both the patients (in the no-pain condition towards the in-group members) and the healthy controls (in the no-pain and pain conditions towards the adversary out-group) suggests that OT enhances the distinction between conflictual in-group and out-group members.

Associations between oxytocin receptor genotypes and social cognitive performance in individuals with schizophrenia

Individuals with schizophrenia often show substantial deficits in social cognitive abilities, which are strongly associated with social functioning. To advance our understanding of the genetic variation that is associated with social cognitive deficits in schizophrenia, we genotyped 74 schizophrenia outpatients who completed social cognitive performance measures assessing mentalizing, social perception, and emotional intelligence, as well as clinical symptoms. We assessed seven single nucleotide polymorphisms (SNPs) of the oxytocin receptor (OXTR) previously found to show replicable associations with socio-emotional processes. For one of the seven SNPs, rs2268493, the 'T' allele was significantly associated with poorer performance on a composite social cognition index, as well as specific tests of mentalizing and social perception. None of the SNPs were associated with clinical symptoms. Though the sample size is small, these findings provide initial support for the involvement of genetic variants of the OXTR in social cognitive impairments in schizophrenia.