Interaction of 5-HTTLPR and a variation on the oxytocin receptor gene influences negative emotionality

Affective Neuroscience Personality Scale (ANPS) and clinical implications: A systematic review

BACKGROUND

Affective neuroscience (AN) theory assumes the existence of seven basic emotional systems (i.e., SEEKING, ANGER, FEAR, CARE, LUST, SADNESS, PLAY) that are common to all mammals and evolutionarily determined to be tools for survival and, in general, for fitness. Based on the AN approach, the Affective Neuroscience Personality Scales (ANPS) questionnaire was developed to examine individual differences in the defined basic emotional systems. The current systematic review aims to examine the use of ANPS in clinical contexts attempting to define those behavioral elements associated with underlying stable personality traits.

METHODS

The systematic review was conducted following the PRISMA statements. PubMed and PsycInfo were used for research literature from March 2003 to November 2021.

RESULTS

Forty-four studies including ANPS were identified from 1763 studies reviewed. Sixteen studies met the inclusion criteria.

LIMITATIONS

The review comprised some papers with incomplete psychological assessments (e.g., lack of other measures in addition to the ANPS) and missing information (e.g., on the [sub]samples), which may affect the generalizability of findings.

CONCLUSION

Specific endophenotypes and/or patterns of emotional/motivational systems were found for several mental disorders. Specifically, endophenotypes emerged for the Depressive and Autism Spectrum Disorders, Borderline and Avoidant Personality Disorders, type I and II Bipolar Disorders, and the Obsessive-Compulsive Disorder. The endophenotypes can provide useful reflective elements for both psychodiagnosis and intervention. Overall, the current study may represent an attempt to contribute to the understanding of the basic emotional systems involved in the psychopathological manifestations identified by AN.

Linking primary emotional traits to ideological attitudes and personal value types

The present study aimed at investigating associations of both ideological attitudes and personal value types with the personality traits derived from the Affective Neuroscience Theory (ANT). For that, data of N = 626 (n = 403 men, n = 220 women, n = 3 identifying as neither a man nor a woman) participants of an online survey in the German language were analyzed. Relations of primary emotional traits derived from the ANT with Right-Wing Authoritarianism (RWA), Social Dominance Orientation (SDO), and personal value types, such as the higher-order value type dimensions "Conservation-Openness to Change" and "Self-Enhancement-Self-Transcendence", were examined by means of correlational analyses and structural equation modeling. Results revealed among others relations between low SEEKING, high ANGER and high RWA. Low CARE and high ANGER were associated with high SDO. Moreover, FEAR was related to the higher-order value type dimension ranging from Conservation to Openness to Change. ANGER was associated with the higher-order value type dimension ranging from Self-Enhancement to Self-Transcendence. The present results do not only expand knowledge on the personality traits associated with ideological attitudes and personal value types. Beyond this, considering the neuroanatomical, functional, and neurochemical correlates of the primary emotional traits SEEKING, ANGER, CARE, and FEAR, the present results may provide a roadmap for forthcoming studies aiming at examining biological correlates of ideological attitudes and personal value types, such as those works in the field of political neuroscience.

Self-Conscious Emotions and the Right Fronto-Temporal and Right Temporal Parietal Junction

For more than two decades, research focusing on both clinical and non-clinical populations has suggested a key role for specific regions in the regulation of self-conscious emotions. It is speculated that both the expression and the interpretation of self-conscious emotions are critical in humans for action planning and response, communication, learning, parenting, and most social encounters. Empathy, Guilt, Jealousy, Shame, and Pride are all categorized as self-conscious emotions, all of which are crucial components to one’s sense of self. There has been an abundance of evidence pointing to the right Fronto-Temporal involvement in the integration of cognitive processes underlying the expression of these emotions. Numerous regions within the right hemisphere have been identified including the right temporal parietal junction (rTPJ), the orbitofrontal cortex (OFC), and the inferior parietal lobule (IPL). In this review, we aim to investigate patient cases, in addition to clinical and non-clinical studies. We also aim to highlight these specific brain regions pivotal to the right hemispheric dominance observed in the neural correlates of such self-conscious emotions and provide the potential role that self-conscious emotions play in evolution.

Prefrontal-limbic-striatum dysconnectivity associated with negative emotional endophenotypes in bipolar disorder during depressive episodes

BACKGROUND

The prefrontal-limbic-subcortical network has been suggested as an important circuitry in the pathophysiology underlying bipolar disorder during depressive episodes (BDD). However, the relationships between disrupted prefrontal-limbic-subcortical connection and the emotional endophenotypes in BDD patients remain largely unclear.

METHODS

Forty-three BDD patients and 63 matched healthy controls (HCs) underwent the resting-state functional magnetic resonance imaging scan. The altered clusters were first identified by using a spatial pairwise clustering method and then were extracted as regions of interest to calculate the functional connectivity (FC). Group comparisons were conducted to identify the abnormal FCs. Classification analysis was employed to examine whether the altered FCs could distinguish BDD from HCs. The relationships between FC alterations and the emotional endophenotypes as measured by the Affective Neuroscience Personality Scales (ANPS) were further detected in BDD.

RESULTS

Compared with HCs, BDD patients showed abnormal FCs in the prefrontal-limbic-striatum circuit. Importantly, the altered FCs yielded 84.91% accuracy (p< 1/5000) with 93.65% sensitivity and 72.09% specificity in differentiating between BDD and HCs. Moreover, the decreased FCs in the prefrontal-striatum and prefrontal-limbic systems were positively correlated with negative emotional endophenotypes of Sadness and Fear scores.

CONCLUSIONS

The findings demonstrated that prefrontal-limbic-striatum disconnection may be identified as a potential effective biomarker for BDD, which could help further explain the neurobiological mechanisms underlying BDD.

A comprehensive review of studies using the Affective Neuroscience Personality Scales in the psychological and psychiatric sciences

Jaak Panksepp's Affective Neuroscience Theory (ANT) belongs to the most prominent emotion theories in the psychological and psychiatric sciences. ANT proposes the existence of seven primary emotional systems deeply anchored in the mammalian brain. These emotional/motivational systems have been shaped by evolutionary processes and function as tools for survival in mammalian species. The systems are called SEEKING, LUST, CARE, and PLAY, as well as ANGER, FEAR, and SADNESS. Panksepp carved out these emotional systems via means of deep brain stimulation, brain lesion and pharmacological manipulation studies. Davis et al. (2003) designed the Affective Neuroscience Personality Scales (ANPS) against the background of findings from ANT. This self-report inventory is meant to enable researchers to assess individual differences in primary emotional systems. Seventeen years have passed since the first version of the ANPS has been published. Therefore, we now provide a comprehensive overview on studies using the ANPS including work from personality science, psychiatry and the neurosciences.

Burnout in university faculty: An interaction between subjective sleep quality and the OXTR rs2268498 polymorphism

BACKGROUND

Job burnout is a stress-related syndrome influenced by both genetic and environmental factors. Poor sleep quality acting as a stressor may lead to job burnout. The oxytocin receptor gene (OXTR) related to stress reactivity may also exert an effect on job burnout. We aimed to explore the effect of sleep quality, a functional OXTR rs2268498 polymorphism, and their interaction on job burnout in the Chinese population, which has not been explored yet.

METHODS

A preliminary study was performed using a cross-sectional design. The Pittsburgh Sleep Quality Index (PSQI) and the Malash Burnout Inventory (MBI) were measured from 575 healthy subjects. The OXTR rs2468498 polymorphism was genotyped in 376 subjects.

RESULTS

There were significant main effects of sleep quality (p<0.05), but not of the OXTR rs2468498 genotype on burnout. Interestingly, the interaction between sleep quality and the rs2468498 genotype was significant (p<0.05). In the poor sleep group, the C allele (C/C and T/C) carriers showed higher Emotional Exhaustion level than T homozygotes, while in the good sleep group, the C allele carrier showed a lower Emotional Exhaustion level.

LIMITATIONS

This study covered subjects from only one university and the sample size for genotyping was relatively small. As we analyzed only the OXTR rs2268498 polymorphism, this study could not reveal the effects of the cerebrospinal oxytocin concentration and the haplotypes.

CONCLUSIONS

Our findings suggest that the OXTR polymorphism modulates the influence of subjective sleep quality on burnout. We conclude that the C allele of the OXTR rs2468498 polymorphism plays a susceptible role in job burnout.

Influence of Two Single-Nucleotide Polymorphisms of the Oxytocin Receptor Gene (OXTR) on Empathy: the Mediation Role of a Primary Emotion, CARE

To feel other's pain would elicit empathy. Some theorists hypothesized that observing other's pain may activate the primary emotion of maternal care instinct, which may function as a precursor of empathy. The maternal care instinct and empathy share the same genetic background and neuroendocrine underpinnings. An extensive body of research has shown that maternal behaviors relate to the oxytocinergic system, which has a strong influence on empathy. These studies suggest that the maternal care instinct may mediate the effect of oxytocin receptor gene (OXTR) on empathy. To provide evidence for this mediation, we used the subscale of CARE in Affective Neuroscience Personality Scales (ANPS) to measure the maternal care instinct and tested two OXTR single-nucleotide polymorphisms (SNPs), rs53576 and rs13316193, in 880 high school participants (588 females, 292 males; M_age = 16.51 years old, SD = 0.65). Results showed that the genotype of rs13316193 was indirectly associated with empathy via CARE, suggesting a mediating role of CARE in the pathway from OXTR to empathy. These findings may contribute to an understanding of how empathy emerges when one witnesses another person in pain.

The neuroscience of sadness: A multidisciplinary synthesis and collaborative review

Sadness is typically characterized by raised inner eyebrows, lowered corners of the mouth, reduced walking speed, and slumped posture. Ancient subcortical circuitry provides a neuroanatomical foundation, extending from dorsal periaqueductal grey to subgenual anterior cingulate, the latter of which is now a treatment target in disorders of sadness. Electrophysiological studies further emphasize a role for reduced left relative to right frontal asymmetry in sadness, underpinning interest in the transcranial stimulation of left dorsolateral prefrontal cortex as an antidepressant target. Neuroimaging studies - including meta-analyses - indicate that sadness is associated with reduced cortical activation, which may contribute to reduced parasympathetic inhibitory control over medullary cardioacceleratory circuits. Reduced cardiac control may - in part - contribute to epidemiological reports of reduced life expectancy in affective disorders, effects equivalent to heavy smoking. We suggest that the field may be moving toward a theoretical consensus, in which different models relating to basic emotion theory and psychological constructionism may be considered as complementary, working at different levels of the phylogenetic hierarchy.

Oxytocin amplifies the influence of good intentions on social judgments

Studies have shown that the evolutionarily conserved neuropeptide oxytocin (OT) promotes various prosocial behaviors, yet there are few studies of the effect of OT on social judgments, especially on judgments when the actor's intention and the final outcome are incongruent. In a double-blind, placebo-controlled experiment, participants were asked to play the role of the recipient in a dictator game and to make social judgments about the dictator after intranasal OT administration. To isolate the outcome and the intention of the dictator's allocation, we developed a novel social judgment task in which recipients were told that 50% of the dictators' proposals would be reversed. The results showed that the effect of OT on social judgment was modulated by intention: OT increased goodness ratings only towards dictators with hyperfair intention. Our findings support the affiliative-motivation theory which states that OT enhances the affiliative motivation and recognition of positive-valence social stimuli.

Translational Studies in the Complex Role of Neurotransmitter Systems in Anxiety and Anxiety Disorders

Discovery of innovative anxiolytics is severely hampering. Existing anxiolytics are developed decades ago and are still the therapeutics of choice. Moreover, lack of new drug targets forecasts a severe jeopardy in the future treatment of the huge population of CNS-diseased patients. We simply lack the knowledge on what is wrong in brains of anxious people (normal and diseased). Translational research, based on interacting clinical and preclinical research, is extremely urgent. In this endeavor, genetic and genomic approaches are part of the spectrum of contributing factors. We focus on three druggable targets: serotonin transporter, 5-HT_1A, and GABA_A receptors. It is still uncertain whether and how these targets are involved in normal and diseased anxiety processes. For serotonergic anxiolytics, the slow onset of action points to indirect effects leading to plasticity changes in brain systems leading to reduced anxiety. For GABA_A benzodiazepine drugs, acute anxiolytic effects are found indicating primary mechanisms directly influencing anxiety processes. Close translational collaboration between fundamental academic and discovery research will lead to badly needed breakthroughs in the search for new anxiolytics.

An epistasis between dopaminergic and oxytocinergic systems confers risk of post-traumatic stress disorder in a traumatized Chinese cohort

Post-traumatic stress disorder (PTSD) is a psychiatric syndrome that occurs after trauma exposure. Neurotransmitters such as dopamine and oxytocin have been reported to be involved in neuropathology of PTSD. Previous studies indicated that the dopamine–oxytocin interaction may contribute to behavioral disorders. Thus, exploring the epistasis (gene–gene interaction) between oxytocinergic and dopaminergic systems might be useful to reveal the genetic basis of PTSD. In this study, we analyzed two functional single nucleotide polymorphisms (SNPs), rs2268498 for oxytocinergic gene OXTR and rs1801028 for dopaminergic gene DRD2 based on putative oxytocin receptor–dopamine receptor D2 (OTR–DR2) heterocomplex in a Chinese cohort exposed to the 2008 Wenchuan earthquake (156 PTSD cases and 978 controls). Statistical analyses did not find any single variant or gene–environment interaction (SNP × earthquake-related trauma exposure) associated with provisional PTSD diagnosis or symptoms. An OXTR–DRD2 interaction (rs2268498 × rs1801028) was identified to confer risk of provisional PTSD diagnosis (OR = 9.18, 95% CI = 3.07–27.46 and P = 7.37e-05) and further subset analysis indicated that rs2268498 genotypes controlled the association directions of rs1801028 and rs1801028 genotypes also controlled the association directions of rs2268498. Rs2268498 × rs1801028 is also associated with PTSD symptoms (P = 0.043). Our study uncovered a genetic and putative function-based contribution of dopaminergic–oxytocinergic system interaction to PTSD.

rs2572431 Polymorphism on Chromosome 8 Is Associated With Individual Differences in Anxiety Related Coping Modes

OBJECTIVE

The role of genetic factors in the interplay between anxiety-related coping and personality has been the subject of interest in numerous previous studies. The current study focused on anxiety-related coping modes, namely repression versus sensitization (i.e., cognitive avoidance versus vigilance), and the single nucleotide polymorphism (SNP) rs2572431. An association between this SNP and anxiety-related personality traits has previously been shown in a genome wide association study, thus further investigation of the relationship between this SNP and anxiety-related coping seems warranted.

METHODS

In the present study, N = 880 mostly Caucasian participants (n = 269 males and n = 611 females; mean-age: 23.88, SD = 7.19) filled in a personality questionnaire assessing individual differences in cognitive avoidance and vigilance, and all participants were genotyped for rs2572431.

RESULTS

Participants homozygous for the T-allele in rs2572431 showed the highest vigilance scores in all scenarios tested. This is in line with findings from an earlier genome wide association study demonstrating that the T-allele is also associated with higher neuroticism scores.

CONCLUSION

The current study yields evidence for the role of rs2572431 in the molecular genetic underpinnings of coping modes and, more broadly, for its connection with personality.

The serotonin transporter gene variants modulate acute stress-induced hippocampus and dorsomedial prefrontal cortex activity during memory retrieval

The short (s) allele of a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) is related to reduced serotonin transporter efficiency and an increased vulnerability to stress and mental disorders. In the present study, we investigated how 5-HTTLPR impacts on memory retrieval under stress and related neural activity by reanalyzing a small genetic neuroimaging data set. Twenty-seven healthy male volunteers participated in both the Trier Social Stress Test (TSST) and a respective control procedure and then their brain activity was measured with functional MRI (fMRI) while they performed an emotional-face-recognition task. Sixteen participants were carriers of the short allele (ss/sl carriers) and 11 were homozygous for the long allele (ll carriers). Genotype groups were compared with respect to stress-related physiological changes, memory performance, and brain activity. No significant genotype-dependent effects on memory performance or cortisol levels were found. The ss/sl carriers showed significantly higher systolic and diastolic blood pressure than the ll carriers, independent of stress. The ss/sl carriers reported stronger stress-induced nervous mood than the ll carriers. Our fMRI data revealed that the ss/sl carriers showed significantly weaker left hippocampus activation and stronger dorsomedial prefrontal cortex (dmPFC) deactivation when retrieving memories under stress as compared with the ll carriers. Subsequent analyses revealed that the distinct hippocampal activation pattern in both genotypes was associated with stress-induced cortisol elevation, while the distinct dmPFC activation pattern in both genotypes was associated with stress-induced changes in reaction times. Our results thus add new evidence that serotonin signaling modulates neural activity in the hippocampus and dmPFC during memory retrieval under acute psychosocial stress.

Central 5-hydroxytryptamine (5-HT) mediates colonic motility by hypothalamus oxytocin-colonic oxytocin receptor pathway

Gut-derived 5-hydroxytryptamine (5-HT) is well known for its role in mediating colonic motility function. However, it is not very clear whether brain-derived 5-HT is involved in the regulation of colonic motility. In this study, we used central 5-HT knockout (KO) mice to investigate whether brain-derived 5-HT mediates colonic motility, and if so, whether it involves oxytocin (OT) production in the hypothalamus and OT receptor in the colon. Colon transit time was prolonged in KO mice. The OT levels in the hypothalamus and serum were decreased significantly in the KO mice compared to wild-type (WT) controls. OT increased colonic smooth muscle contraction in both KO and WT mice, and the effects were blocked by OT receptor antagonist and tetrodotoxin but not by hexamethonium or atropine. Importantly, the OT-induced colonic smooth muscle contraction was decreased significantly in the KO mice relative to WT. The OT receptor expression of colon was detected in colonic myenteric plexus of mice. Central 5-HT is involved in the modulation of colonic motility which may modulate through its regulation of OT synthesis in the hypothalamus. Our results reveal a central 5-HT - hypothalamus OT - colonic OT receptor axis, providing a new target for the treatment of brain-gut dysfunction.

Affective Neuroscience Theory and Personality: An Update

The present work gives a short overview of central aspects of Jaak Panksepp's Affective Neuroscience Theory (AN theory) and its relevance for modern personality neuroscience. In contrast to the widely used Big Five approach to studying and understanding human personality, AN theory provides researchers with a distinct roadmap to the biological basis of personality, including molecular and neuroanatomical candidates, to understand individual differences in human behavior. Such molecular and neuroanatomical brain candidates have been derived by means of electrical brain stimulation and pharmacological challenges, while investigating primary emotional systems anchored in the subcortical mammalian brain. Research results derived from the study of emotions in mammals are also of relevance for humans because ancient layers of our minds-those layers where primary emotions originate-have been homologously conserved across species. From an evolutionary perspective, this makes sense because primal emotions represent "built-in tools for survival" for all mammals. In this context, Montag and Panksepp recently illustrated a potential ancient neurobiological effect by carving out robust associations between individual differences in primary emotions (assessed via self-report) and the Big Five in a cross-cultural study with data from the United States, Germany, and China. These associations together with some ideas derived from MacLean's Triune Brain concept highlighted (a) that primary emotions likely represent the phylogenetically oldest parts of human personality and (b) that primary emotions influence human personality in a bottom-up fashion given their localization in ancient subcortical brain regions. A comment on the work by Montag and Panksepp asked for insights on putative links between primary emotions and facets of the Big Five. Therefore, we provide some first insights into such associations from recent Germany data. In addition, the present work provides a new short version of the Affective Neuroscience Personality Scales to assess individual differences in primary emotions.

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.

The association of childhood maltreatment with depression and anxiety is not moderated by the oxytocin receptor gene

BACKGROUND

The oxytocin receptor (OXTR) gene may be involved in resilience or vulnerability towards stress, and hence in the development of stress-related disorders. There are indications that OXTR single nucleotide polymorphisms (SNPs) interact with early life stressors in predicting levels of depression and anxiety. To replicate and extend these findings, we examined whether three literature-based OXTR SNPs (rs2254298, rs53576, rs2268498) interact with childhood maltreatment in the development of clinically diagnosed depression and anxiety disorders.

METHODS

We included 2567 individuals from the Netherlands Study of Depression and Anxiety. This sample consisted of 387 healthy controls, 428 people with a current or past depressive disorder, 243 people with a current or past anxiety disorder, and 1509 people with both lifetime depression and anxiety diagnoses. Childhood maltreatment was measured with both an interview and via self-report. Additional questionnaires measured depression and anxiety sensitivity.

RESULTS

Childhood maltreatment was strongly associated with both lifetime depression and anxiety diagnoses, as well as with depression and anxiety sensitivity. However, the OXTR SNPs did not moderate these associations nor had main effects on outcomes.

CONCLUSIONS

The three OXTR gene SNPs did not interact with childhood maltreatment in predicting lifetime depression and anxiety diagnoses or sensitivity. This stresses the importance of replication studies with regard to OXTR gene variants in general populations as well as in clearly established clinical samples.

Polymorphisms of the oxytocin receptor gene and overeating: the intermediary role of endophenotypic risk factors

Background/Objectives:

Oxytocin (OXT) is an evolutionarily ancient neuropeptide with strong links to affiliative and prosocial behaviors, and the management of stress. Increases in OXT also tend to decrease food intake, especially of sweet carbohydrates. The social correlates of low OXT levels mesh with the social deficits and stress proneness identified in interpersonal models of overeating, as well as the increased appetite for highly palatable foods typically seen in chronic overeaters. The objectives of this study were to investigate links between polymorphisms of the oxytocin receptor (OXTR) gene and overeating, and to examine OXTR links with relevant endophenotypes of overeating related to reward and stress sensitivity, and to food preferences.

Subject/Methods:

The sample comprised 460 adults between the ages of 25 and 50 years recruited from the community, and representing a broad range of body weights. Overeating, reward and punishment sensitivity, and food preferences, were quantified as composite variables using well-validated questionnaires. In addition, seven single-nucleotide polymorphisms (rs237878, rs237885, rs2268493, rs2268494, rs2254298, rs53576, rs2268498) of the OXTR gene were genotyped.

Results:

Analyses identified a four-marker haplotype that was significantly related to food preferences. Individual genotype analyses also found that at least one of the markers was related to each of the phenotypic variables. In addition, an empirically derived structural equation model linking genetic and phenotype variables produced a good fit to the data.

Conclusions:

The results of this preliminary study have demonstrated that OXTR variation is associated with overeating, and with endophenotypic traits such as sweet and fatty food preferences, and reward and punishment sensitivity. In general, the genetic findings also favor the view that overeating may be associated with relatively low basal OXT levels.

Primary Emotional Systems and Personality: An Evolutionary Perspective

The present article highlights important concepts of personality including stability issues from the perspective of situational demands and stability over the life-course. Following this more introductory section, we argue why individual differences in primary emotional systems may represent the phylogenetically oldest parts of human personality. Our argumentation leads to the need to increasingly consider individual differences in the raw affects/emotions of people to understand human personality in a bottom-up fashion, which can be coordinated with top-down perspectives. In support of this idea, we also review existing evidence linking individual differences in primal emotions as assessed with the Affective Neuroscience Personality Scales and the widely accepted Big Five Model of Personality. In this context, we provide additional evidence on the link between primal emotions and personality in German and Chinese sample populations. In short, this article addresses evolutionary perspectives in the evaluation of human personality, highlighting some of the ancestral emotional urges that probably still control variations in the construction of human personality structures. Moreover, we address how individual differences in primary emotional systems can illuminate linkages to major human psychopathologies and the potential advantages and disadvantages of carrying a certain personality trait within certain cultural/environmental niches.

Oxytocin and Anxiety Disorders

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

Overview of Human Oxytocin Research

Social dysfunction is a core symptom of many psychiatric disorders and current medications have little or no remedial effects on this. Following on from extensive studies on animal models demonstrating that the neuropeptide oxytocin plays an important role in social recognition and bonding, human-based research has explored its therapeutic potential for social dysfunction in psychiatric disorders. Here we outline the historical background of this human-based research and some of the current methodological challenges it is facing. To date, research has primarily attempted to establish functional effects through measuring altered endogenous concentrations, observing effects of exogenous administration and by investigating the effects of polymorphisms and epigenetic modifications of the oxytocin receptor gene. We summarize some of the key findings on behavioral and neural effects that have been reported in healthy subjects in the context of social cognition which have provided encouragement that oxytocin could represent a promising therapeutic target. At the same time, we have identified a number of key areas where we urgently need further information about optimal dosing strategies and interactions with other peptide and transmitter systems. Finally, we have summarized current translational findings, particularly in the context of therapeutic outcomes of intranasal oxytocin administration in autism and schizophrenia. These clinical findings while somewhat varied in outcome do offer increasing cause for optimism that targeting the oxytocin system may provide a successful therapeutic approach for social dysfunction. However, future research needs to focus on the most effective treatment strategy and which types of individuals are likely to benefit most.

An Affective Neuroscience Framework for the Molecular Study of Internet Addiction

Internet addiction represents an emerging global health issue. Increasing efforts have been made to characterize risk factors for the development of Internet addiction and consequences of excessive Internet use. During the last years, classic research approaches from psychology considering personality variables as vulnerability factor, especially in conjunction with neuroscience approaches such as brain imaging, have led to coherent theoretical conceptualizations of Internet addiction. Although such conceptualizations can be valuable aid, the research field is currently lacking a comprehensive framework for determining brain-based and neurochemical markers of Internet addiction. The present work aims at providing a framework on the molecular level as a basis for future research on the neural and behavioral level, in order to facilitate a comprehensive neurobiological model of Internet addiction and its clinical symptomatology. To help establish such a molecular framework for the study of Internet addiction, we investigated in N = 680 participants associations between individual differences in tendencies toward Internet addiction measured by the Generalized Problematic Internet Use Scale-2 (GPIUS-2) and individual differences in primary emotional systems as assessed by the Affective Neuroscience Personality Scales (ANPS). Regression analysis revealed that the ANPS scales FEAR and SADNESS were the ANPS scales most robustly positively linked to several (sub)scales of the GPIUS-2. Also the scales SEEKING, CARE and PLAY explain variance in some of the GPIUS-2 subscales. As such, these scales are negatively linked to the GPIUS-2 subscales. As the ANPS has been constructed on substantial available brain data including an extensive molecular body with respect to evolutionary highly conserved emotional circuitry in the ancient mammalian brain, the present study gives first ideas on putative molecular mechanisms underlying different facets of Internet addiction as derived from associations between tendencies toward Internet addiction and individual differences in primary emotional systems. For example, as SADNESS is linked to the overall GPIUS-2 score, and the neuropeptide oxytocin is known to downregulate SADNESS, it is conceivable that the neuropeptide might play a role in Internet addition on the molecular level. Our findings provide a theoretical framework potentially illuminating the molecular underpinnings of Internet addiction. Finally, we also present data on the ANPS and smartphone addiction at the end of the paper. Similar to the reported associations between the ANPS and the GPIUS-2, these correlations might provide an initial outline for a framework guiding future studies that aim to address the molecular basis of smartphone addiction.

The serotonin system in autism spectrum disorder: From biomarker to animal models

Elevated whole blood serotonin, or hyperserotonemia, was the first biomarker identified in autism spectrum disorder (ASD) and is present in more than 25% of affected children. The serotonin system is a logical candidate for involvement in ASD due to its pleiotropic role across multiple brain systems both dynamically and across development. Tantalizing clues connect this peripheral biomarker with changes in brain and behavior in ASD, but the contribution of the serotonin system to ASD pathophysiology remains incompletely understood. Studies of whole blood serotonin levels in ASD and in a large founder population indicate greater heritability than for the disorder itself and suggest an association with recurrence risk. Emerging data from both neuroimaging and postmortem samples also indicate changes in the brain serotonin system in ASD. Genetic linkage and association studies of both whole blood serotonin levels and of ASD risk point to the chromosomal region containing the serotonin transporter (SERT) gene in males but not in females. In ASD families with evidence of linkage to this region, multiple rare SERT amino acid variants lead to a convergent increase in serotonin uptake in cell models. A knock-in mouse model of one of these variants, SERT Gly56Ala, recapitulates the hyperserotonemia biomarker and shows increased brain serotonin clearance, increased serotonin receptor sensitivity, and altered social, communication, and repetitive behaviors. Data from other rodent models also suggest an important role for the serotonin system in social behavior, in cognitive flexibility, and in sensory development. Recent work indicates that reciprocal interactions between serotonin and other systems, such as oxytocin, may be particularly important for social behavior. Collectively, these data point to the serotonin system as a prime candidate for treatment development in a subgroup of children defined by a robust, heritable biomarker.

The Role of Nature and Nurture for Individual Differences in Primary Emotional Systems: Evidence from a Twin Study

The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS) by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings), moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33%) and highest for the PLAY system (69%). Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research.

On the role of oxytocin in borderline personality disorder

OBJECTIVES

Interpersonal dysfunction is central to borderline personality disorder (BPD). Recent research has focused on the role of oxytocin (OT) in BPD, particularly regarding associations of OT activity with symptoms, genetic polymorphisms of the oxytocin receptor coding gene (OXTR) in BPD, and experimental modification of interpersonal core problems of patients with BPD such as hypervigilance towards threat detection, mistrust, and non-verbal behaviour during social interaction by intranasal application of OT.

METHODS

A literature ('medline') review was performed using the keywords 'oxytocin' and 'borderline personality disorder'. Secondary literature on trauma and attachment in relation to OT was also considered relevant.

RESULTS

Together, findings suggest that in BPD OT is associated with enhanced defensive mechanisms and avoidance behaviour. Moreover, gene-environment interaction concerning polymorphic variations of the OXTR gene and childhood adversity in BPD suggests that these genes convey developmental flexibility or 'differential susceptibility' to environmental contingencies, whereby BPD resides at the poor outcome end of the spectrum.

CONCLUSIONS

In view of the conflicting literature, it needs to be studied carefully whether OT can serve as a therapeutic agent given adjunct to psychotherapy in BPD. More research about the role of OT is also required with regard to the prevention of the non-genetic intergenerational transmission of BPD. Clarifying the role of OT in BPD may also benefit from research in non-human animals targeting the interaction between early adversity and OT availability more directly.

PRACTITIONER POINTS

The study of oxytocin can contribute to the understanding of the neurobiology of borderline personality disorder. Oxytocin is critically involved in attachment security, and methylation of the oxytocin receptor may play a role in the epigenetic modulation of early adversity. The intranasal application of oxytocin may be a useful therapeutic adjunct to psychotherapy. Insecure attachment and childhood adversity may produce differential neurobiological effects on the oxytocinergic system in borderline personality disorder. There is insufficient knowledge of how oxytocin interacts with vasopressin, testosterone, dopamine, and serotonin, which are also important key players in the experience of social reward and stress responsivity. It is unclear whether or not oxytocin could be beneficial in preventing the intergenerational (non-genetic) transmission of borderline personality traits.

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.

Parental Perceptions of Aggressive Behavior in Preschoolers: Inhibitory Control Moderates the Association With Negative Emotionality

Inhibitory control (IC) and negative emotionality (NE) are both linked to aggressive behavior, but their interplay has not yet been clarified. This study examines different NE × IC interaction models in relation to aggressive behavior in 855 preschoolers (aged 2-5 years) using parental questionnaires. Hierarchical regression analyses revealed that NE and IC predict aggression both directly and interactively. The highest aggression levels were reported in children with high NE and low IC. Interestingly, the protective effect of IC for aggressive behavior increases with rising levels of NE. Analyses focusing on physical aggression revealed a significant NE × IC interaction in boys aged 4-5 years only. These findings shed new light on potential compensatory mechanisms for aggressive behavior in developing children.

Genetic modulation of oxytocin sensitivity: a pharmacogenetic approach

Intranasal administration of the neuropeptide oxytocin has been shown to influence a range of complex social cognitions and social behaviors, and it holds therapeutic potential for the treatment of mental disorders characterized by social functioning deficits such as autism, social phobia and borderline personality disorder. However, considerable variability exists in individual responses to oxytocin administration. Here, we undertook a study to investigate the role of genetic variation in sensitivity to exogenous oxytocin using a socioemotional task. In a randomized, double-blind, placebo-controlled experiment with a repeated-measures (crossover) design, we assessed the performance of 203 men on an emotion recognition task under oxytocin and placebo. We took a haplotype-based approach to investigate the association between oxytocin receptor gene variation and oxytocin sensitivity. We identified a six-marker haplotype block spanning the promoter region and intron 3 that was significantly associated with our measure of oxytocin sensitivity. Specifically, the TTCGGG haplotype comprising single-nucleotide polymorphisms rs237917-rs2268498-rs4564970-rs237897-rs2268495-rs53576 is associated with increased emotion recognition performance under oxytocin versus placebo, and the CCGAGA haplotype with the opposite pattern. These results on the genetic modulation of sensitivity to oxytocin document a significant source of individual differences with implications for personalized treatment approaches using oxytocin administration.

Examining gene-environment interactions in comorbid depressive and disruptive behavior disorders using a Bayesian approach

OBJECTIVE

The objective of this study was to apply a Bayesian statistical analytic approach that minimizes multiple testing problems to explore the combined effects of chronic low familial support and variants in 12 candidate genes on risk for a common and debilitating childhood mental health condition.

METHOD

Bayesian mixture modeling was used to examine gene by environment interactions among genetic variants and environmental factors (family support) associated in previous studies with the occurrence of comorbid depression and disruptive behavior disorders youth, using a sample of 255 children.

RESULTS

One main effect, variants in the oxytocin receptor (OXTR, rs53576) was associated with increased risk for comorbid disorders. Two significant gene × environment and one signification gene × gene interactions emerged. Variants in the nicotinic acetylcholine receptor α5 subunit (CHRNA5, rs16969968) and in the glucocorticoid receptor chaperone protein FK506 binding protein 5 (FKBP5, rs4713902) interacted with chronic low family support in association with child mental health status. One gene × gene interaction, 5-HTTLPR variant of the serotonin transporter (SERT/SLC6A4) in combination with μ opioid receptor (OPRM1, rs1799971) was associated with comorbid depression and conduct problems.

CONCLUSIONS

Results indicate that Bayesian modeling is a feasible strategy for conducting behavioral genetics research. This approach, combined with an optimized genetic selection strategy (Vrieze et al., 2012), revealed genetic variants involved in stress regulation (FKBP5, SERT × OPMR), social bonding (OXTR), and nicotine responsivity (CHRNA5) in predicting comorbid status.

Oxytocin enables novelty seeking and creative performance through upregulated approach: evidence and avenues for future research

Oxytocin is an evolutionary ancient hypothalamic neuropeptide well known for its role in reproduction, social bonding, and group affiliation. Recent work has linked oxytocin in humans to creative cognition--the ability to produce insights, ideas, and problem solutions that are original and potentially useful. Here we review this literature, focusing on the relationship between (1) single-nucleotide polymorphisms in the oxytocin receptor (OXTR) gene; endogenous oxytocin from blood plasma, and intranasal administration of oxytocin (vs placebo), and (2) creativity-related traits (e.g., novelty seeking, extraversion, and openness to experience), and behaviors (e.g., exploration, divergent thinking, original ideation, and problem solving). Findings are interpreted in the context of the dual pathway to creativity model and except for OXTR: (1) reveal a weak to moderate but consistent association between oxytocin and creativity, which emerges because (2) oxytocin enables the cognitive flexibility pathway more than persistent information processing. Findings can be best understood in terms of oxytocin's putative effects on dopaminergic activity and concomitant approach tendency.

The oxytocin receptor gene and social perception

Social perception is an important prerequisite for successful social interaction, because it helps to gain information about behaviors, thoughts, and feelings of interaction partners. Previous pharmacological studies have emphasized the relevance of the oxytocin system for social perception abilities, while knowledge on genetic contributions is still scarce. In the endeavor to fill this gap in the literature, the current study searches for associations between participants' social perception abilities as measured by the interpersonal perception task (IPT) and the rs2268498 polymorphism on the OXTR-gene, which has repeatedly been linked to processes relevant to social functioning. N = 105 healthy participants were experimentally tested with the IPT and genotyped for the rs2268498 polymorphism. T-allele carriers (TT and TC genotypes) exhibited significantly better performance in the IPT than carriers of the CC-genotype. This difference was also significant for the subscales measuring the strength of social bonding (kinship and intimacy). As in previous studies, T-allele carriers exhibited better performance in measures of social processing indicating that the rs2268498 polymorphism is an important candidate for understanding the genetic basis of social functioning.

Variation in the oxytocin receptor gene is associated with behavioral and neural correlates of empathic accuracy

The neuromodulators oxytocin and serotonin have been implicated in regulating affective processes underlying empathy. Understanding this dependency, however, has been limited by a lack of objective metrics for measuring empathic performance. Here we employ a novel psychophysical method for measuring empathic performance that quantitatively measures the ability of subjects to decode the experience of another person's pain. In 50 female subjects, we acquired functional magnetic resonance imaging data as they were exposed to a target subject experiencing variable degrees of pain, whilst performing an irrelevant attention-demanding task. We investigated the effect of variation in the oxytocin receptor gene (OXTR) and the serotonin transporter gene (SLC6A4) on the psychophysical and neurometric variability associated with empathic performance. The OXTR rs2268498 and rs53576 polymorphisms, but not the SLC6A4 5-HTTLPR, were associated with significant differences in empathic accuracy, with CC- and AA-carriers, respectively, displaying higher empathic accuracy. For OXTR rs2268498 there was also a genotype difference in the correlation between empathic accuracy and activity in the superior temporal sulcus (STS). In OXTR rs2268498 CC-carriers, high empathic accuracy was associated with stronger responsiveness of the right STS to the observed pain. Together, the results show that genetic variation in the OXTR has significant influence on empathic accuracy and that this may be linked to variable responsivity of the STS.

Clock gene modulates roles of OXTR and AVPR1b genes in prosociality

BACKGROUND

The arginine vasopressin receptor (AVPR) and oxytocin receptor (OXTR) genes have been demonstrated to contribute to prosocial behavior. Recent research has focused on the manner by which these simple receptor genes influence prosociality, particularly with regard to the AVP system, which is modulated by the clock gene. The clock gene is responsible for regulating the human biological clock, affecting sleep, emotion and behavior. The current study examined in detail whether the influences of the OXTR and AVPR1b genes on prosociality are dependent on the clock gene.

METHODOLOGY/PRINCIPAL FINDINGS

This study assessed interactions between the clock gene (rs1801260, rs6832769) and the OXTR (rs1042778, rs237887) and AVPR1b (rs28373064) genes in association with individual differences in prosociality in healthy male Chinese subjects (n = 436). The Prosocial Tendencies Measure (PTM-R) was used to assess prosociality. Participants carrying both the GG/GA variant of AVPR1b rs28373064 and the AA variant of clock rs6832769 showed the highest scores on the Emotional PTM. Carriers of both the T allele of OXTR rs1042778 and the C allele of clock rs1801260 showed the lowest total PTM scores compared with the other groups.

CONCLUSIONS

The observed interaction effects provide converging evidence that the clock gene and OXT/AVP systems are intertwined and contribute to human prosociality.

The Brain Derived Neurotrophic Factor and Personality

The study of the biological basis of personality is a timely research endeavor, with the aim of deepening our understanding of human nature. In recent years, a growing body of research has investigated the role of the brain derived neurotrophic factor (BDNF) in the context of individual differences across human beings, with a focus on personality traits. A large number of different approaches have been chosen to illuminate the role of BDNF for personality, ranging from the measurement of BDNF in the serum/plasma to molecular genetics to (genetic) brain imaging. The present review provides the reader with an overview of the current state of affairs in the context of BDNF and personality.

Negative emotionality mediates the association of 5-HTTLPR genotype and depression in children with and without ADHD

The 44-base-pair polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) has been implicated in the etiology of depression, but relatively little is known about potential mediators of this association. Although dimensions of temperament are likely to be proximal to the neurobiological and genetic factors underlying depression, studies have yet to formally evaluate temperament as a potential causal pathway. We examined individual differences in dimensions of temperament [negative emotionality (NE), prosociality (PRO), and daring (DA)] as potential mediators of 5-HTTLPR genotype and child depression. Using a multiple mediation framework, we tested the association of child 5-HTTLPR genotype and these dimensions of temperament with multi-informant ratings of child depression in a sample of 218 children with and without attention-deficit/hyperactivity disorder (ADHD). The long allele of 5-HTTLPR was associated with higher NE and lower PRO, but not DA. High NE mediated the association of 5-HTTLPR genotype and separate parent and teacher ratings of depression. ADHD status did not moderate the mediational role of NE for 5-HTTLPR and depression. Results suggest that NE may constitute a pathway between 5-HTTLPR and child depression. The role of genetic variation and temperament dimensions as intermediate traits in the development of depression is discussed.

Plasma oxytocin changes and anti-obsessive response during serotonin reuptake inhibitor treatment: a placebo controlled study

BACKGROUND

The drug treatments of choice for obsessive-compulsive disorder (OCD) are serotonin reuptake inhibitors (SRIs). However, a correlation between the neuropeptide oxytocin in cerebrospinal fluid and the severity of OCD has previously been shown, and oxytocin and serotonin are interconnected within the brain. Few studies have investigated whether SRIs have any effect on oxytocin; thus, our aim was to explore the possibility that oxytocinergic mechanisms contribute to the anti-obsessive effect of SRIs.

METHOD

In a randomized, double-blind trial, comparing SRIs (clomipramine and paroxetine) with placebo in 36 adults with OCD (characterized for subtypes), plasma oxytocin was measured with radioimmunoassay after plasma extraction, at baseline, after 1 week, and after 4 weeks of treatment, and related to baseline severity and clinical response after 12 weeks, as measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).

RESULTS

Baseline oxytocin levels correlated positively with baseline Y-BOCS ratings, but only among the future SRI responders. Patients with early onset of OCD had higher baseline oxytocin. During treatment, plasma oxytocin did not differ between SRI and placebo treatment. In SRI responders, plasma oxytocin first decreased and then increased; in non-responders (to SRI as well as to placebo), the reverse was the case. After 4 weeks, treatment responders had attained higher oxytocin levels compared to non-responders. The intra-individual range (i.e., the variability) of plasma oxytocin between measurements was the measure that best differentiated responders from non-responders. This range was higher in responders than non-responders, and lower in patients with autistic traits.

CONCLUSIONS

SRIs have highly variable effects on plasma oxytocin between individuals. The associations between baseline oxytocin and OCD severity and between oxytocin changes and treatment response support the notions that oxytocin is involved in OCD pathophysiology, and that the anti-obsessive effects of SRIs are partly exerted through oxytocinergic mechanisms.

Attachment, affective temperament, and personality disorders: a study of their relationships in psychiatric outpatients

BACKGROUND

As the result of extensive translational and cross-disciplinary research, attachment theory is now a construct with significant neuropsychiatric traction. The correlation of attachment with other influential conceptual models (i.e. temperament and personality) is therefore of interest. Consequently, we explored how two attachment dimensions (attachment anxiety and attachment avoidance) correlated with measures of temperament and personality in 357 psychiatric outpatients.

METHODS

We performed a retrospective review of four questionnaires (the Experiences in Close Relationship scale (ECR-R), Temperament and Character inventory (TCI), Temperament Evaluation of the Memphis, Pisa, Paris and San Diego questionnaire (TEMPS-A), and Personality Self-Portrait Questionnaire (PSQ)). Frequency measures and correlations were examined, as was the predictive value of attachment security for a personality disorder (PD).

RESULTS

Significant, robust correlations were found between attachment anxiety and (1) several negative affective temperaments (dysthymic and cyclothymic); (2) several indices of personality pathology (low self-directedness (TCI), DSM-IV paranoid, borderline, histrionic, avoidant and dependent personality traits). Attachment avoidance had fewer large correlations. In an exploratory model, the negative predictive value of attachment security for a PD was 86%.

LIMITATIONS

Subjects were a relatively homogeneous subset of ambulatory psychiatric outpatients. PD diagnoses were via self-report.

CONCLUSIONS

Clinically, these findings highlight the significant overlap between attachment, affective temperament, and personality and support the value of attachment as a screen for PDs. More broadly, given our growing understanding of the neurobiology of attachment (i.e. links with the oxytocin system), these results raise interesting questions about underlying biological systems and psychiatric treatment.

An interaction between oxytocin and a genetic variation of the oxytocin receptor modulates amygdala activity toward direct gaze: evidence from a pharmacological imaging genetics study

The neuropeptide oxytocin plays an important role in social cognition. One valuable tool to study social cognition in healthy and autistic humans in a neuroscientific context is the investigation of gaze toward another person. Of importance, it has been demonstrated that pronounced amygdala activation could be observed, when participants are confronted with direct gaze pictures in an fMRI setting, an effect that can be particularly observed in autistic individuals. In the present study, a combined pharmacological imaging genetics study has been conducted to further investigate the biological basis of direct gaze processing. N = 55 healthy males were invited to an oxytocin challenge study administered while watching direct vs. averted gaze pictures in an fMRI setting. In addition, the promoter region of the oxytocin receptor (OXTR) gene of the participants was investigated to search for individual differences in the recorded BOLD signal. The main result revealed that a genetic variation of the OXTR gene (rs401015) modulated the right amygdala activity for the fMRI contrast "direct > averted gaze" under the influence of the neuropeptide oxytocin. Here, carriers of the heterozygous CT variant showed higher activity compared to the TT group. The present study highlights the role of individual differences in a genetic variant of the OXTR gene for amygdala activation during processing of direct gaze pictures after intranasal oxytocin administration. In sum, the study shows the importance of combining a pharmacological challenge with genetic imaging to better understand the biological basis of social cognition.

The role of the serotonergic and GABA system in translational approaches in drug discovery for anxiety disorders

There is ample evidence that genetic factors play an important role in anxiety disorders. In support, human genome-wide association studies have implicated several novel candidate genes. However, illumination of such genetic factors involved in anxiety disorders has not resulted in novel drugs over the past decades. A complicating factor is the heterogeneous classification of anxiety disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) and diverging operationalization of anxiety used in preclinical and clinical studies. Currently, there is an increasing focus on the gene × environment (G × E) interaction in anxiety as genes do not operate in isolation and environmental factors have been found to significantly contribute to the development of anxiety disorders in at-risk individuals. Nevertheless, extensive research on G × E mechanisms in anxiety has not resulted in major breakthroughs in drug discovery. Modification of individual genes in rodent models has enabled the specific study of anxiety in preclinical studies. In this context, two extensively studied neurotransmitters involved in anxiety are the gamma-aminobutyric acid (GABA) and 5-HT (5-hydroxytryptamine) system. In this review, we illustrate the complex interplay between genes and environment in anxiety processes by reviewing preclinical and clinical studies on the serotonin transporter (5-HTT), 5-HT1A receptor, 5-HT2 receptor, and GABAA receptor. Even though targets from the serotonin and GABA system have yielded drugs with known anxiolytic efficacy, the relation between the genetic background of these targets and anxiety symptoms and development of anxiety disorders is largely unknown. The aim of this review is to show the vast complexity of genetic and environmental factors in anxiety disorders. In light of the difficulty with which common genetic variants are identified in anxiety disorders, animal models with translational validity may aid in elucidating the neurobiological background of these genes and their possible role in anxiety. We argue that, in addition to human genetic studies, translational models are essential to map anxiety-related genes and to enhance our understanding of anxiety disorders in order to develop potentially novel treatment strategies.

Epigenetic regulation of the oxytocin receptor gene: implications for behavioral neuroscience

Genetic approaches have improved our understanding of the neurobiological basis of social behavior and cognition. For instance, common polymorphisms of genes involved in oxytocin signaling have been associated with sociobehavioral phenotypes in healthy samples as well as in subjects with mental disorders. More recently, attention has been drawn to epigenetic mechanisms, which regulate genetic function and expression without changes to the underlying DNA sequence. We provide an overview of the functional importance of oxytocin receptor gene (OXTR) promoter methylation and summarize studies that have investigated the role of OXTR methylation in behavioral phenotypes. There is first evidence that OXTR methylation is associated with autism, high callous-unemotional traits, and differential activation of brain regions involved in social perception. Furthermore, psychosocial stress exposure might dynamically regulate OXTR. Given evidence that epigenetic states of genes can be modified by experiences, especially those occurring in sensitive periods early in development, we conclude with a discussion on the effects of traumatic experience on the developing oxytocin system. Epigenetic modification of genes involved in oxytocin signaling might be involved in the mechanisms mediating the long-term influence of early adverse experiences on socio-behavioral outcomes.

On the genetic basis of face cognition and its relation to fluid cognitive abilities

The oxytocin and the dopaminergic systems have turned out to be highly relevant for social abilities and cognition. Therefore, we examined the association between two functional gene polymorphisms and face cognition (FC) in a multivariate study (N = 250) by applying structural equation modeling. The catechol-O-methyltransferase (COMT) val158met polymorphism influences the enzyme activity of COMT, which affects the prefrontal dopamine concentration. The rs226849 is a single-nucleotide polymorphism located in the promoter region of the oxytocin receptor (OXTR) gene, modulating the mRNA expression. By modeling a general fluid ability factor (defined by working memory and reasoning) and nested FC factors, we tested genetic contributions to FC, after controlling for variance in FC that was also associated with fluid abilities. In line with several previous studies, we found a significant association between the COMT genotype and fluid abilities (Gf) but not with FC. The association between the oxytocin polymorphism and Gf was opposite in direction for men and women. Women with the C(+) genotype performed better on Gf tasks than those with the C(-) genotype. Conversely, men with the C(-) genotype performed better than those with the C(+) genotype. There was no significant association between OXTR and the nested FC factor. Therefore, the relationship between the oxytocin polymorphism and FC can be fully accounted for by Gf. The sex specificity of this relationship is a novel finding and warrants a mechanistic explanation.