Mu opioid receptor polymorphism, early social adversity, and social traits

Could Relationship-Based Learnt Beliefs and Expectations Contribute to Physiological Vulnerability of Chronic Pain? Making a Case to Consider Attachment in Pain Research

Pain is an interpersonal and inherently social experience. Pain perception and administration of medical treatment all occur in a particular environmental and social context. Early environmental influences and early learning experiences and interactions condition the body's response to different threats (like pain), ultimately shaping the underlying neurophysiology. These early interactions and experiences also determine what situations are perceived as threatening, as well as our belief in our own ability to self-manage, and our belief in others to offer support, during perceived threats. These beliefs intrinsically drive the combination of behaviors that emerge in response to perceived threats, including pain. Such behaviors can be categorized into attachment styles. In this interdisciplinary review, we synthesize and summarize evidence from the neurobiological, psychobiological, psychosocial, and psychobehavioral fields, to describe how these beliefs are embedded in the brain's prediction models to generate a series of expectations/perceptions around the level of safety/threat in different contexts. As such, these beliefs may predict how one experiences and responds to pain, with potentially significant implications for the development and management of chronic pain. Little attention has been directed to the effect of adult attachment style on pain in research studies and in the clinical setting. Using interdisciplinary evidence, we argue why we think this interaction merits further consideration and research. PERSPECTIVE: This review explores the influence of attachment styles on pain perception, suggesting a link between social connections and chronic pain development. It aligns with recent calls to emphasize the social context in pain research and advocates for increased focus on adult attachment styles in research and clinical practice.

Anxious-depressive attack and rejection sensitivity-Toward a new approach to treatment-resistant depression

This paper aimed to find clues to treatment-resistant depression (TRD) solutions. Depression comorbid with anxiety is often treatment-resistant where anxious-depressive attack (ADA) often lurks. ADA is a recently proposed clinical idea for just a psychological version of a panic attack. It mostly begins with an abrupt surge of intense anxiety followed by uninterrupted intrusive thoughts; lasting ruminations about regret or worry produced by violent anxiety, agitation, and loneliness. Acting-out behaviors such as deliberate self-injury and over-dose may also be observed during the attack. As the basic psychopathology of ADA, rejection sensitivity (RS) was revealed by a structural equation model. It is said that the presence of RS in depressive disorders implies a poor prognosis. The following biological markers for RS were reviewed in the literature: first, the involvement of the μ-opioid receptor function in RS and, secondly, hypersensitivity of the dopamine D4 receptor (DRD4) in the medial prefrontal cortex. The latter has been suggested in fear-conditioned animal experiments. Manipulation of the μ-opioid receptor function together with the DRD4 function may culminate in a treatment for RS, which could contribute to the development of a treatment for TRD via the improvement of ADA.

The interplay between parental care and OPRM1 in reward responsiveness

The Reinforcement Sensitivity Theory (RST) explains a variety of reward-motivated behaviors as the result of the activation of biologically-based systems. Inspired by the influences of parental bonding and opioid peptide on reward system, we investigated the contributions of parental bonding and mu-opioid receptor gene (OPRM1) towards motivation systems (i.e., the BAS, BIS-anxiety, and FFFS-fear). Results indicated that (1) parental care was negatively related to FFFS-fear, but parental overprotection was positively related to both FFFS-fear and BIS-anxiety; (2) parental care significantly interacted with OPRM1 rs1799971 in reward responsiveness with diathesis-stress model. Poor parental care reduced reward responsiveness among individuals with the G allele, but not those with the AA genotype. These findings from this study demonstrate a new gene-environment interactive mechanism of the RST.

Unraveling the Contribution of Serotonergic Polymorphisms, Prefrontal Alpha Asymmetry, and Individual Alpha Peak Frequency to the Emotion-Related Impulsivity Endophenotype

The unique contribution of the serotonin transporter-linked polymorphic region (5-HTTLPR), intronic region 2 (STin2), and monoamine oxidase A (MAO-A) genes to individual differences in personality traits has been widely explored, and research has shown that certain forms of these polymorphisms relate to impulsivity and impulsivity-related disorders. Humans showing these traits are also described as having an asymmetrical prefrontal cortical activity when compared to others. In this explorative study, we examine the relationship between serotonergic neurotransmission polymorphisms, cortical activity features (prefrontal alpha asymmetry, individual alpha peak frequency [iAPF]), emotion-related and non-emotion-related impulsivity in humans. 5-HTTLPR, MAO-A, and STin2 polymorphisms were assessed in blood taken from 91 participants with high emotion-related impulsivity levels. Sixty-seven participants completed resting electroencephalography and a more comprehensive impulsivity index. In univariate analyses, iAPF correlated with both forms of emotion-related impulsivity. In multiple linear regression models, 5-HTTLPR polymorphism (model 1, adj. R² = 15.2%) and iAPF were significant interacting predictors of emotion-related impulsivity, explaining a large share of the results’ variance (model 2, adj. R² = 21.2%). Carriers of the low transcriptional activity 5-HTTPLR and MAO-A phenotypes obtained higher emotion-related impulsivity scores than others did. No significant results were detected for non-emotion-related impulsivity or for a form of emotion-related impulsivity involving cognitive/motivational reactivity to emotion. Our findings support an endophenotypic approach to impulsivity, showing that tri-allelic 5-HTTLPR polymorphism, iAPF, and their interaction are relevant predictors of one form of emotion-related impulsivity.

Association Between the A118G Polymorphism of the OPRM1 Gene and Suicidal Depression in a Large Cohort of Outpatients with Depression

BACKGROUND

Growing evidences suggest that depression with suicidal ideation (SI) could be a specific phenotype with its own characteristics. Moreover, opioid system deregulation might be implicated in suicidal behaviour (SB). The aim of this study was to determine whether the A118G polymorphism (rs1799971) in ORPM1 (the gene encoding opioid receptor mu 1) is associated with suicidal depression (ie, moderate to severe depression with SI) in a large cohort of outpatients with depression.

METHODS

GENESE is a large, prospective, naturalistic cohort of French adult outpatients with depression (DSM-IV criteria), treated and followed for 6 weeks. Depression severity was assessed with the Hospital Anxiety and Depression Scale (HADS), and SI with the suicidal item of the Montgomery-Åsberg Depression Rating Scale (MADRS-SI). From this cohort, patients with moderate or severe depression (HADS-D subscale score >11) were selected and classified as without SI (MADRS-SI < 2), or with SI (MADRS-SI ≥ 2).

RESULTS

The AA/AG genotypes of the A118G polymorphism were significantly associated with suicidal depression in the non-adjusted (OR = 2.32, 95% CI = [1.28; 4.18]; p-value = 0.005) and in the adjusted models (OR = 2.54, 95% CI = [1.35; 4.78]; p-value = 0.004).

CONCLUSION

Outpatients with depression harbouring the A allele are at higher risk of SI (and possibly SB) than those carrying the G allele. More studies are needed to better understand the link between this polymorphism and SB.

Oxytocin Receptor Gene (OXTR) and Childhood Adversity Influence Trust

Early-life environments have been associated with various social behaviors, including trust, in late adolescence and adulthood. Given that the oxytocin receptor gene polymorphism (OXTR rs53576) moderates the impact of childhood experience on social behaviors, in the present study, we examined the main effect of childhood adversity through a self-report measure and its interactions with OXTR rs53576 on general trust among 203 Japanese and 200 European Canadian undergraduate students. After controlling for the effect of culture, the results indicated that childhood adversity had a negative association with general trust, and that OXTR rs53576 moderated the impact of childhood adversity on general trust. Specifically, the negative association between childhood adversity and general trust is only significant among homozygote A-allele carriers. These findings demonstrated that OXTR rs53576 moderated the relations between childhood experiences and social functioning in early adulthood.

The μ-opioid receptor gene A118G polymorphism is associated with insecure attachment in children with disruptive mood regulation disorder and their mothers

BACKGROUND

The A118G single nucleotide polymorphism (SNP) of the μ-opioid receptor gene, with high expression of the A allele and low expression of the G allele, has been associated with emotional/behavioral dysregulation and depressive disorders and is recognized as a mediator of affiliative behavior. No study has thus far investigated this SNP in school-age children with disruptive mood regulation disorder (DMDD). This study compared a sample of healthy children and their mothers with a sample of children with DMDD and their mothers, evaluating whether insecure attachment and psychopathological symptoms are associated with A allele- or G allele-carrying mothers and children and whether caregiving capacities are associated with A allele- or G allele-carrying mothers.

METHODS

For evaluation of their psychopathological symptoms and attachment styles, mothers filled out the CBCL/6-18, the SCL-90-R, and the ECR. To evaluate the types of relationship children were experiencing with their mothers, children filled out the ECR-revised child version and the PBI. Genotypic analyses were conducted on DNA samples obtained by buccal swabbing from children and mothers.

RESULTS

An insecure attachment style was more frequent in mothers and children carrying the G allele (G/G + A/G genotypes). In the clinical sample, G allele-carrying children scored higher than homozygous A/A ones on the subscales of Withdrawal and Conduct Problems. G-carrying mothers showed higher interpersonal sensitivity, depression, hostility, and paranoid ideation and provided less care than A/A mothers.

CONCLUSIONS

This study offers new insights into the associations between the A118G SNP of the μ-opioid receptor gene and emotional/behavioral functioning, attachment style in children, and psychopathology and caregiving ability in mothers.

Genetic Influences on Social Relationships: Sex Differences in the Mediating Role of Personality and Social Cognition

Objectives

In humans (and primates more generally), evolutionary fitness arises by two separate routes: conventional reproduction build around dyadic relationships and, reflecting the processes of group augmentation selection, how well individuals are embedded in their community. These processes are facilitated by a suite of genetically inherited neuroendocrines and neurotransmitters. It is not, however, known whether these effects are directly due to genetic factors or are mediated by aspects of personality, or whether there are sex differences in the way this is organised.

Methods

We examine whether dispositional factors related to the processing of social information, such as personality (Big 5 and Impulsivity), attachment style (Anxious and Avoidant dimensions) and sociocognitive capacity (emotion recognition) mediate associations between variation in receptor genes for oxytocin, vasopressin, beta-endorphin, dopamine, serotonin, testosterone and two core social relationship indices (the Sociosexual Orientation Index [SOI] and Support Network size).

Results

In men, variation in dopamine genes indirectly influences SOI through its effect on Impulsivity. In contrast, in women, variation in endorphin and vasopressin genes independently affect Openness to Experience, which mediates indirect effects of these genes on SOI. Moreover, endorphin gene variation also impacts on Network Size in women (but not men), via Extraversion.

Conclusions

These findings reveal that dispositional aspects of personality mediate some genetic effects on behaviour, thereby extending our understanding of how genetic and dispositional variation interact to determine individual differences in human sexual and social cognition and behaviour. The differences between the sexes seem to reflect differences in the two sexes’ social strategies.

Understanding the Scientific Basis of Post-traumatic Stress Disorder (PTSD): Precision Behavioral Management Overrides Stigmatization

Post-traumatic stress disorder (PTSD) is a severe polygenic disorder triggered by environmental factors. Many polymorphic genes, particularly the genetic determinants of hypodopaminergia (low dopamine function), associate with a predisposition to PTSD as well as substance use disorder. Support from the National Institutes of Health for neuroimaging research and molecular, genetic applied technologies has improved understanding of brain reward circuitry functions that have inspired the development of new innovative approaches to their early diagnosis and treatment of some PTSD symptomatology and addiction. This review presents psychosocial and genetic evidence that vulnerability or resilience to PTSD can theoretically be impacted by dopamine regulation. From a neuroscience perspective, dopamine is widely accepted as a major neurotransmitter. Questions about how to modulate dopamine clinically in order to treat and prevent PTSD and other types of reward deficiency disorders remain. Identification of genetic variations associated with the relevant genotype-phenotype relationships can be characterized using the Genetic Addiction Risk Score (GARS®) and psychosocial tools. Development of an advanced genetic panel is under study and will be based on a new array of genes linked to PTSD. However, for now, the recommendation is that enlistees for military duty be given the opportunity to voluntarily pre-test for risk of PTSD with GARS, before exposure to environmental triggers or upon return from deployment as part of PTSD management. Dopamine homeostasis may be achieved via customization of neuronutrient supplementation "Precision Behavioral Management" (PBM™) based on GARS test values and other pro-dopamine regulation interventions like exercise, mindfulness, biosensor tracking, and meditation.

Polymorphism A118G of opioid receptor mu 1 (OPRM1) is associated with emergence of suicidal ideation at antidepressant onset in a large naturalistic cohort of depressed outpatients

Antidepressants have been the object of an international controversy for about thirty years. Some patients are inclined to develop suicidal ideation (SI) at antidepressant onset; this phenomenon is known as Treatment Emergent Suicidal Ideation (TESI), and it has conducted regulatory bodies to prompt warnings on antidepressants. Since, few studies have explored the pharmacogenomics of TESI. Given the growing body of evidence connecting the opioidergic system with suicidal behavior (particularly mu opioid receptor (MOR)), we decided to examine the relationship between two genetic polymorphisms (SNPs) in the opioidergic system and TESI in a sample of 3566 adult depressed outpatients. General practitioners and psychiatrists throughout France followed participants for 6 weeks after an initial prescription of tianeptine, an antidepressant treatment with mu agonism. Suicidal ideation was assessed with the item 10 of the Montgomery-Asberg Depression Rating Scale (item dedicated to SI) at baseline, and after 2 weeks, 4 weeks and 6 weeks. We analysed rs1799971 from the OPRM1 gene and rs105660 from the OPRK1 gene. Within the sample, 112 patients reported TESI while 384 did not. We found a significant association between AA genotype of rs1799971 and TESI even after adjustment for potential cofounders (OR = 1.93, 95% CI = [1.07; 3.49]; p-value = 0.03). On the other hand there were no significant association between rs1799971 and rs105560 with worsening of suicidal ideation or lifetime suicide attempts. Nevertheless, our results suggest a possible involvement of opioidergic system in TESI.

Parental overcontrol x OPRM1 genotype interaction predicts school-aged children's sympathetic nervous system activation in response to performance challenge

Parental overcontrol (OC), the excessive regulation of a child's behavior, cognition, and emotion, is associated with the development of child anxiety. While studies have shown that genetic factors may increase sensitivity to stress, genetic vulnerability to parental OC has not been examined in anxiety etiology. A functional polymorphism in the mu opioid receptor OPRM1 (A118G, rs1799971) has been shown to impact stress reactivity. Using a community sample of children (N = 85, 9-12 years old), we examined the main and interactive effects of maternal OC and child OPRM1 genotype in predicting children's sympathetic nervous system reactivity during a performance stressor. Neither OC nor genotype predicted children's electrodermal activity (EDA); however, the interaction between OC and child genotype significantly predicted stress reactivity, as indexed by EDA, during the challenging task. Among children with the minor G-allele, higher maternal OC was associated with higher reactivity. In A homozygotes, maternal OC was not associated with EDA, suggesting a diathesis-stress pattern of gene x environment interaction. We discuss implications for anxiety etiology and intervention.

Interaction between the Opioid Receptor OPRM1 Gene and Mother-Child Language Style Matching Prospectively Predicts Children's Separation Anxiety Disorder Symptoms

Recent research suggests that lower mother-child language style matching (LSM) is associated with greater physiological reactivity and insecure attachment in school-aged children, but to date no studies have explored this measure of parent-child behavioral matching for its association with children's anxiety symptoms, a well-known correlate of attachment insecurity and heightened physiological reactivity. There is also considerable evidence of genetic risk for anxiety, including possession of the OPRM1 minor allele, 118G. In the current study (N = 44), we expand upon what is known about children's genetic and environmental risk for anxiety by examining the unique and interactive effects of mother-child LSM and the OPRM1 polymorphism A118G on school-aged children's separation anxiety disorder (SAD) symptoms. SAD symptoms were measured both concurrently with LSM and OPRM1 genotype and two years later through self-report. No significant associations emerged between LSM or OPRM1 and concurrent Time 1 SAD symptoms. However, lower LSM and 118G minor allele possession were both associated with greater SAD symptoms at Time 2; further, the interaction between LSM and OPRM1 genotype significantly predicted SAD symptoms beyond the main effects of the two variables. Possession of the minor allele was only associated with greater SAD symptoms among children in low LSM dyads, whereas children with the minor allele in high LSM dyads showed non-significantly lower SAD symptoms. These findings and a proportion affected analysis provide support for a differential susceptibility model of gene by environment interactions for the OPRM1 gene. We discuss the implications for predicting children's separation anxiety across development.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

μ opioid receptor, social behaviour and autism spectrum disorder: reward matters

The endogenous opioid system is well known to relieve pain and underpin the rewarding properties of most drugs of abuse. Among opioid receptors, the μ receptor mediates most of the analgesic and rewarding properties of opioids. Based on striking similarities between social distress, physical pain and opiate withdrawal, μ receptors have been proposed to play a critical role in modulating social behaviour in humans and animals. This review summarizes experimental data demonstrating such role and proposes a novel model, the μ opioid receptor balance model, to account for the contribution of μ receptors to the subtle regulation of social behaviour. Interestingly, μ receptor null mice show behavioural deficits similar to those observed in patients with autism spectrum disorder (ASD), including severe impairment in social interactions. Therefore, after a brief summary of recent evidence for blunted (social) reward processes in subjects with ASD, we review here arguments for altered μ receptor function in this pathology. This article is part of a themed section on Emerging Areas of Opioid Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.14/issuetoc.