Individual Differences in Childhood Behavior Disorders Associated With Epigenetic Modulation of the Cortisol Receptor Gene

Maternal sensitivity and child internalizing and externalizing behavior: a mediating role for glucocorticoid receptor gene (NR3C1) methylation?

The early caregiving environment can have lasting effects on child mental health. Animal models suggest that glucocorticoid receptor gene (NR3C1) DNA methylation plays a mediating role in linking more responsive caregiving to improved behavioral outcomes by its impact on the stress regulatory system. In this longitudinal study, we examined whether children's NR3C1 methylation levels mediate an effect of maternal sensitivity in infancy on levels of child internalizing and externalizing behavior in a community sample. Maternal sensitivity of 145 mothers was rated at infant age 5 weeks, 12 months, and 30 months by observing mother-infant interactions. Buccal DNA methylation was assessed in the same children at age 6 years and maternal-reported internalizing and externalizing behavior was assessed at age 6 and 10 years. Higher sensitivity at age 5 weeks significantly predicted lower DNA methylation levels at two NR3C1 CpG loci, although methylation levels at these loci did not mediate an effect of maternal sensitivity on levels of child internalizing and externalizing behavior. Overall, the study provides evidence that maternal sensitivity in early infancy is associated with DNA methylation levels at loci involved in stress regulation, but the significance of this finding for child mental health remains unclear.

DNA methylation variation after a parenting program for child conduct problems: Findings from a randomized controlled trial

This study investigated associations of the Incredible Years (IY) parenting program with children's DNA methylation. Participants were 289 Dutch children aged 3-9 years (75% European ancestry, 48% female) with above-average conduct problems. Saliva was collected 2.5 years after families were randomized to IY or care as usual (CAU). Using an intention-to-treat approach, confirmatory multiple-regression analyses revealed no significant differences between the IY and CAU groups in children's methylation levels at the NR3C1 and FKBP5 genes. However, exploratory epigenome-wide analyses revealed nine differentially methylated regions between groups, coinciding with SLAMF1, MITF, FAM200B, PSD3, SNX31, and CELSR1. The study provides preliminary evidence for associations of IY with children's salivary methylation levels and highlights the need for further research into biological outcomes of parenting programs.

Epigenome-wide meta-analysis of prenatal maternal stressful life events and newborn DNA methylation

Prenatal maternal stressful life events are associated with adverse neurodevelopmental outcomes in offspring. Biological mechanisms underlying these associations are largely unknown, but DNA methylation likely plays a role. This meta-analysis included twelve non-overlapping cohorts from ten independent longitudinal studies (N = 5,496) within the international Pregnancy and Childhood Epigenetics consortium to examine maternal stressful life events during pregnancy and DNA methylation in cord blood. Children whose mothers reported higher levels of cumulative maternal stressful life events during pregnancy exhibited differential methylation of cg26579032 in ALKBH3. Stressor-specific domains of conflict with family/friends, abuse (physical, sexual, and emotional), and death of a close friend/relative were also associated with differential methylation of CpGs in APTX, MyD88, and both UHRF1 and SDCCAG8, respectively; these genes are implicated in neurodegeneration, immune and cellular functions, regulation of global methylation levels, metabolism, and schizophrenia risk. Thus, differences in DNA methylation at these loci may provide novel insights into potential mechanisms of neurodevelopment in offspring.

The Emotionally Sensitive Child-Adverse Parenting Experiences-Allostatic (Over)Load (ESCAPE-AL) Model for the Development of Secondary Psychopathic Traits

Understanding and treatment of antisocial behavior have improved through efforts to subtype individuals based on similar risk factors and outcomes. In particular, the presence of psychopathic traits is associated with distinct etiological factors and antisocial behavior that begins early in life, is aggressive, persistent, and less likely to normalize with traditional treatments, relative to individuals low on psychopathy or its childhood precursor, callous-unemotional (CU) traits. However, important distinctions can be made within individuals with CU/psychopathic traits according to the presence of elevated anxiety symptoms and/or adverse childhood experiences, known as secondary psychopathy/CU traits. This paper provides a broad and brief overview of theory and empirical literature supporting the existence of secondary psychopathy/CU variants as a distinct subtype of childhood antisocial behavior. It outlines the Emotionally Sensitive Child-Adverse Parenting Experiences-Allostatic (Over)Load (ESCAPE-AL) model for the developmental psychopathology of secondary psychopathic/CU traits and discusses research and theory supporting this perspective. Future research directions for testing this conceptual model and its implications for assessing and treating high-risk individuals with secondary CU/psychopathic traits are discussed.

Perceived Parental Support and Psychological Control, DNA Methylation, and Loneliness: Longitudinal Associations Across Early Adolescence

A broad range of factors have been associated with the development of adolescent loneliness. In the family context, a lack of parental support and high levels of parental psychological control have systematically been linked to loneliness. On the biological level, DNA methylation (which is an epigenetic process that suppresses gene expression) is believed to play a role in the development of loneliness. Specifically, high levels of DNA methylation in genes that play an important role in the functioning of the human stress response system are believed to elevate the risk of loneliness. Moreover, DNA methylation levels in these stress-related genes can be influenced by stressful environmental factors, suggesting a potential mediating role of DNA methylation in the association between parenting behaviors and loneliness. The current 3-year longitudinal study is the first study to examine the potential bidirectional longitudinal associations between loneliness, DNA methylation in stress-related genes, and both perceived parental support and psychological control. Furthermore, we explored the potential mediating role of DNA methylation in stress-related genes in the associations between perceived parenting and loneliness. The sample comprised 622 early adolescents (55% girls, M_{age T1} = 10.77 years, SD_{age T1} = 0.48) who were followed from Grade 5 to 7. Parental support, psychological control, and loneliness were assessed annually by adolescent self-report questionnaires and DNA methylation was determined from saliva samples. Cross-Lagged Panel Models (CLPM) revealed that higher levels of loneliness predicted lower perceived parental support and higher perceived psychological control over time, as well as higher DNA methylation in some stress-related genes, that is, the glucocorticoid receptor gene (NR3C1) and the brain-derived neurotrophic factor (BDNF). In addition, higher NR3C1 methylation was predictive of lower perceived parental support and higher psychological control over time. No evidence was found for a mediating role of DNA methylation. Overall, our longitudinal findings challenge the current focus on DNA methylation and parenting behaviors as risk factors for adolescent loneliness. Instead, they suggest that the less considered direction of effects, which implies that loneliness predicts DNA methylation and aspects of parenting such as support and psychological control, should receive greater attention in future research.

Association between academic pressure, NR3C1 gene methylation, and anxiety symptoms among Chinese adolescents: a nested case-control study

BACKGROUND

Academic pressure is a prevalent stressor among Chinese adolescents and is often linked to anxiety symptoms, although the underlying mechanism remains unclear. This study aimed to investigate the association between NR3C1 gene methylation, academic pressure, and anxiety symptoms among Chinese adolescents.

METHODS

This nested-case control study included 150 adolescents (boys: 38.7%; baseline age: 12-17 years) from a school-based longitudinal study of Chinese adolescents. Cases (n = 50) were defined as those with anxiety symptoms at both baseline and follow-up, while controls (n = 100) were randomly selected from those without anxiety symptoms at both timepoints. The cases and controls were 1:2 matched by age. Academic pressure, anxiety symptoms, and potential covariates were measured using a self-report questionnaire. Peripheral whole blood samples were collected from each participant for the detection of cortisol level (i.e., morning serum cortisol level) and DNA methylation. The methylation analysis included a total of 27 CpG units at the NR3C1 promoter region.

RESULTS

The final adjusted models showed that students with heavy academic pressure at baseline were at a higher risk of anxiety symptoms at follow-up compared to those with mild academic pressure (β estimate: 6.24 [95% CI: 3.48 ~ 9.01]). After adjusting for covariates, the methylation level of one CpG unit (NR3C1-16 CpG10) in NR3C1 differed significantly between cases and controls (F = 6.188, P = 0.014), and the difference remained significant after correction for multiple testing (P < 0.025). The adjusted regression models showed that moderate (β estimate = 0.010 [95% CI: 0.000 ~ 0.020], P = 0.046) and heavy (β estimate = 0.011 [95% CI: 0.001 ~ 0.020], P = 0.030) academic pressure were significantly associated with the methylation level of NR3C1-16 CpG 10. Further mediation analysis demonstrated that the association of academic pressure and anxiety symptoms was significantly mediated by the methylation of NR3C1-16 CpG 10 (β estimate for indirect effect = 0.11 [95% CI: 0.005 ~ 0.32]; indirect/total effect = 8.3%).

CONCLUSION

The present study suggests that NR3C1-16 CpG 10 DNA methylation might be a potential mechanism that partially explains the lasting effects of academic pressure on subsequent anxiety symptoms among adolescents. Further studies with larger sample sizes are recommended to replicate this finding.

Epigenome-wide DNA methylation in externalizing behaviours: A review and combined analysis

DNA methylation (DNAm) is one of the most frequently studied epigenetic mechanisms facilitating the interplay of genomic and environmental factors, which can contribute to externalizing behaviours and related psychiatric disorders. Previous epigenome-wide association studies (EWAS) for externalizing behaviours have been limited in sample size, and, therefore, candidate genes and biomarkers with robust evidence are still lacking. We 1) performed a systematic literature review of EWAS of attention-deficit/hyperactivity disorder (ADHD)- and aggression-related behaviours conducted in peripheral tissue and cord blood and 2) combined the most strongly associated DNAm sites observed in individual studies (p < 10^-3) to identify candidate genes and biological systems for ADHD and aggressive behaviours. We observed enrichment for neuronal processes and neuronal cell marker genes for ADHD. Astrocyte and granulocytes cell markers among genes annotated to DNAm sites were relevant for both ADHD and aggression-related behaviours. Only 1 % of the most significant epigenetic findings for ADHD/ADHD symptoms were likely to be directly explained by genetic factors involved in ADHD. Finally, we discuss how the field would greatly benefit from larger sample sizes and harmonization of assessment instruments.

DNA methylation as a mediator in the association between prenatal maternal stress and child mental health outcomes: Current state of knowledge

BACKGROUND

Prenatal maternal stress is increasingly recognized as a risk factor for offspring mental health challenges. DNA methylation may be a mechanism, but few studies directly tested mediation. These few integrative studies are reviewed along with studies from three research areas: prenatal maternal stress and child mental health, prenatal maternal stress and child DNA methylation, and child mental health and DNA methylation.

METHODS

We conducted a narrative review of articles in each research area and the few published integrative studies to evaluate the state of knowledge.

RESULTS

Prenatal maternal stress was related to greater offspring internalizing and externalizing symptoms and to greater offspring peripheral DNA methylation of the NR3C1 gene. Youth mental health problems were also related to NR3C1 hypermethylation while epigenome-wide studies identified genes involved in nervous system development. Integrative studies focused on infant outcomes and did not detect significant mediation by DNA methylation though methodological considerations may partially explain these null results.

LIMITATIONS

Operationalization of prenatal maternal stress and child mental health varied greatly. The few published integrative studies did not report conclusive evidence of mediation by DNA methylation.

CONCLUSIONS

DNA methylation likely mediates the association between prenatal maternal stress and child mental health. This conclusion still needs to be tested in a larger number of integrative studies. Key empirical and statistical considerations for future research are discussed. Understanding the consequences of prenatal maternal stress and its pathways of influence will help prevention and intervention efforts and ultimately promote well-being for both mothers and children.

Placental CRH as a Signal of Pregnancy Adversity and Impact on Fetal Neurodevelopment

Early life is a period of considerable plasticity and vulnerability and insults during that period can disrupt the homeostatic equilibrium of the developing organism, resulting in adverse developmental programming and enhanced susceptibility to disease. Fetal exposure to prenatal stress can impede optimum brain development and deranged mother's hypothalamic-pituitary-adrenal axis (HPA axis) stress responses can alter the neurodevelopmental trajectories of the offspring. Corticotropin-releasing hormone (CRH) and glucocorticoids, regulate fetal neurogenesis and while CRH exerts neuroprotective actions, increased levels of stress hormones have been associated with fetal brain structural alterations such as reduced cortical volume, impoverishment of neuronal density in the limbic brain areas and alterations in neuronal circuitry, synaptic plasticity, neurotransmission and G-protein coupled receptor (GPCR) signalling. Emerging evidence highlight the role of epigenetic changes in fetal brain programming, as stress-induced methylation of genes encoding molecules that are implicated in HPA axis and major neurodevelopmental processes. These serve as molecular memories and have been associated with long term modifications of the offspring's stress regulatory system and increased susceptibility to psychosomatic disorders later in life. This review summarises our current understanding on the roles of CRH and other mediators of stress responses on fetal neurodevelopment.

Harsh Parenting Predicts Novel HPA Receptor Gene Methylation and NR3C1 Methylation Predicts Cortisol Daily Slope in Middle Childhood

Adverse experiences in childhood are associated with altered hypothalamic-pituitary-adrenal (HPA) axis function and negative health outcomes throughout life. It is now commonly accepted that abuse and neglect can alter epigenetic regulation of HPA genes. Accumulated evidence suggests harsh parenting practices such as spanking are also strong predictors of negative health outcomes. We predicted harsh parenting at 2.5 years old would predict HPA gene DNA methylation similarly to abuse and neglect, and cortisol output at 8.5 years old. Saliva samples were collected three times a day across 3 days to estimate cortisol diurnal slopes. Methylation was quantified using the Illumina Infinium MethylationEPIC array BeadChip (850 K) with DNA collected from buccal cells. We used principal components analysis to compute a summary statistic for CpG sites across candidate genes. The first and second components were used as outcome variables in mixed linear regression analyses with harsh parenting as a predictor variable. We found harsh parenting significantly predicted methylation of several HPA axis genes, including novel gene associations with AVPRB1, CRHR1, CRHR2, and MC2R (FDR corrected p < 0.05). Further, we found NR3C1 methylation predicted a steeper diurnal cortisol slope. Our results extend the current literature by demonstrating harsh parenting may influence DNA methylation similarly to more extreme early life experiences such as abuse and neglect. Further, we show NR3C1 methylation is associated with diurnal HPA function. Elucidating the molecular consequences of harsh parenting on health can inform best parenting practices and provide potential treatment targets for common complex disorders.

A systematic review of childhood maltreatment and DNA methylation: candidate gene and epigenome-wide approaches

Childhood maltreatment is a major risk factor for chronic and severe mental and physical health problems across the lifespan. Increasing evidence supports the hypothesis that maltreatment is associated with epigenetic changes that may subsequently serve as mechanisms of disease. The current review uses a systematic approach to identify and summarize the literature related to childhood maltreatment and alterations in DNA methylation in humans. A total of 100 empirical articles were identified in our systematic review of research published prior to or during March 2020, including studies that focused on candidate genes and studies that leveraged epigenome-wide data in both children and adults. Themes arising from the literature, including consistent and inconsistent patterns of results, are presented. Several directions for future research, including important methodological considerations for future study design, are discussed. Taken together, the literature on childhood maltreatment and DNA methylation underscores the complexity of transactions between the environment and biology across development.

Prenatal risk factors for internalizing and externalizing problems in childhood

BACKGROUND

A growing body of research has documented the effects of prenatal risk factors on a wide spectrum of adverse offspring health outcomes. Childhood behavior problems, such as externalizing and internalizing problems, are no exception. This comprehensive literature review aims to summarize and synthesize current research about commonly experienced prenatal risk factors associated with internalizing and externalizing problems, with a focus on their impact during childhood and adolescence. Potential mechanisms as well as implications are also outlined.

DATA SOURCES

The EBSCO, Web of Science, PubMed, Google Scholar, and Scopus databases were searched for studies examining the association between prenatal risk factors and offspring internalizing/externalizing problems, using keywords "prenatal" or "perinatal" or "birth complications" in combination with "internalizing" or "externalizing". Relevant articles, including experimental research, systematic reviews, meta-analyses, cross-sectional and longitudinal cohort studies, and theoretical literature, were reviewed and synthesized to form the basis of this integrative review.

RESULTS

Prenatal risk factors that have been widely investigated with regards to offspring internalizing and externalizing problems encompass health-related risk factors, including maternal overweight/obesity, substance use/abuse, environmental toxicant exposure, maternal infection/inflammation, as well as psychosocial risk factors, including intimate partner violence, and anxiety/depression. Collectively, both epidemiological and experimental studies support the adverse associations between these prenatal factors and increased risk of emotional/behavioral problem development during childhood and beyond. Potential mechanisms of action underlying these associations include hormonal and immune system alterations. Implications include prenatal education, screening, and intervention strategies.

CONCLUSIONS

Prenatal risk factors are associated with a constellation of offspring internalizing and externalizing problems. Identifying these risk factors and understanding potential mechanisms will help to develop effective, evidence-based prevention, and intervention strategies.

Epigenetic differences in inflammation genes of monozygotic twins are related to parent-child emotional availability and health

The inflammatory response is an immune defense engaged immediately after injury or infection. Chronic inflammation can be deleterious for various health outcomes and is characterized by high levels of pro-inflammatory markers such as C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α). A large body of research demonstrates these inflammatory markers are responsive to stress and quality of social relationships throughout the lifespan. For example, the quality of the early parental bond predicts various health outcomes and may be driven by changes in immune function. Epigenetic processes, such as DNA methylation, may be one mechanism by which early social experiences shape immune functioning. The present study used a monozygotic twin difference design to assess if mother-reported emotional availability at 1 year and 2.5 years predicted immune gene methylation at 8 years of age. Further, we assessed if inflammation gene methylation was related to general health problems (e.g. infections, allergies, etc.). We found that mother-reported emotional availability at 1 year, but not 2.5 years, was related to methylation of various immune genes in monozygotic twins. Furthermore, twin pairs discordant in health problems have more difference in immune gene methylation compared to twin pairs concordant for health problems, suggesting that methylation of immune genes may have functional consequences for general health. These results suggest that the emotional component of attachment quality during infancy contributes to immune epigenetic profiles in childhood, which may influence general health.

Sex differences in antisocial and aggressive disorders that onset in childhood and persist into adulthood

As many as 10.7% of males and 7.5% of females display early-onset, stable, antisocial and aggressive behavior (ESAAB). Most research has focused on males. These individuals are diagnosed with conduct disorder in childhood and antisocial personality disorder in adulthood, and a very few, almost all males, present the syndrome of psychopathy. ESAAB includes three subgroups: (1) conduct problems and callousness; (2) conduct problems, callousness, and anxiety; and (3) conduct problems. Heritability of the first two subtypes is high. This high heritability derives, at least in part, from genes involved in regulating serotonergic functioning early in life and to genotypes that confer sensitivity to trauma. The first subtype is rare and characterized by difficulty in face emotion recognition, especially fear and sadness, and hypoarousal as indexed by both autonomic and neural measures, and by structural brain abnormalities. By contrast, those with conduct problems, callousness, and anxiety are more common. They include a greater proportion of females and show hypersensitivity to threat that triggers reactive aggression and that is reflected in both autonomic and neural functioning. In sum, fewer females than males present ESAAB, but many characteristics, autonomic and neural correlates, and etiology are similar. Importantly, however, females with ESAAB play a critical role in the intergenerational transfer of antisocial behavior. Despite higher prevalence of EASSB in males than females, few sex differences in neural abnormalities have been identified.

Meta-Analysis of the RDoC Social Processing Domain across Units of Analysis in Children and Adolescents

OBJECTIVE

This meta-analysis advances a framework to understand correspondence among units of analysis of the social processing construct within Research Domain Criteria (RDoC).

METHOD

As requested for this special issue, eligible studies cited an RDoC-initiative paper or mentioned RDoC in the abstract, title, or keywords were empirical and peer reviewed, and described a correlation or regression analysis (r, β, or odds ratio) between two different units of analysis in the social processing domain in youth. We examined the frequency (descriptive statistics) and magnitude of correspondence between unit-pairs (random effects models), and predefined moderators (meta-regression).

RESULTS

Eight of the twenty-eight possible unit-by-unit pairs were identified, with subjective-by-behavior units being the most common. Of those, only subjective-by-circuit had significant correspondence between units. Moderator analysis revealed that the age and diagnosis of generalized anxiety disorder moderated correspondence between subjective-by-circuit units of analysis, and that a diagnosis of autism spectrum disorder moderated correspondence between subjective-by-gene units of analysis. Younger ages and inclusion of either diagnostic group reduced correspondence.

CONCLUSIONS

These findings indicate that the RDoC initiative has generated limited research within the social processing domain across units of analysis in youth to date. Moreover, National Institute of Mental Health (NIMH)-funded studies do not appear to be biased toward supporting the RDoC framework. However, the limited number of included studies precludes the generalizability of these findings and underscores the need for further research. Despite this, results suggest that the NIMH model for providing standard batteries of measurement tools may effectively reduce spurious correlations between subjective-by-behavior units of analysis.

Toward a transdiagnostic model of common and unique processes leading to the major disorders of childhood: The REAL model of attention, responsiveness and learning

There is a growing recognition of the importance of identifying both trans-diagnostic risk factors across the major disorders that onset early in childhood, as well as precise vulnerabilities that differentiate among specific disorders. In this paper, we propose a model to explain individual differences in the development of the major forms of mental health problems that can be identified early in life through excesses and deficits in emotional attention, responsiveness and learning (i.e., the REAL model). The model leads to a number of specific hypotheses relating to trans-diagnostic (common to all disorders) and specific risk to the major mental disorders of childhood. Like earlier models of temperament, the REAL constructs are defined in terms of how the child responds to environmental conditions. Our proposal is that the development of psychopathology is in part based on how adverse environmental conditions trigger, inhibit, and interact with these specific biological vulnerabilities at sensitive periods in the developing human. To illustrate this interplay of biology and experience, we summarize key findings from the growing field of epigenetics and child mental health, arguing that epigenetic processes might mediate the relationship between environmental adversity and the major neurodevelopmental systems of REAL. Finally, we argued that the REAL model highlights important avenues for early intervention based on common and unique factors across childhood disorders.

Reprint of "Epigenetics, maternal prenatal psychosocial stress, and infant mental health"

This paper provides a summary of literature on epigenetic effects and infant health outcomes of maternal psychosocial stress during pregnancy. A search of literature yielded a large body of publications between 2008 and 2018. Relevant articles were selected, and additional sources were located from ancestry searches of reference lists. Results implicate maternal prenatal stress as a source of epigenetic mechanisms that affect fetal brain development and program risk for emotional dysregulation and mental disorders over a lifetime and across generations. Implications for nursing practice are explored at multiple levels of policy advocacy, public education, primary prevention, screening and intervention.

Prenatal Maternal Distress: A Risk Factor for Child Anxiety?

The deleterious association between various types of prenatal maternal psychological distress (PNMS, anxiety, depression, psychological distress, stress) and childhood anxiety symptomatology (internalizing behaviors, anxiety symptoms) has been established using both retrospective and prospective longitudinal studies across varied demographic cohorts and throughout development. Yet, the existing literature cannot claim maternal distress during pregnancy to be a specific risk factor for anxiety symptomatology, as studies utilizing such observational designs are unable to adequately account for confounding of potential genetic factors and the postnatal environment. In this review, we examine studies that attempt to minimize such confounding and thus disentangle the unique intrauterine exposure effect of varying types of PNMS on childhood anxiety symptomatology. Such methodologies include paternal versus maternal comparison studies, sibling comparisons, prenatal cross-fostering designs and timing of exposure studies (including disaster studies). Of the identified studies, findings indicate that prenatal maternal distress is likely to constitute a risk factor for anxiety symptomatology, although more studies are needed to replicate current findings in order to determine whether there are clear differences in effects across specific types of PNMS and for specific subpopulations. We review the methodological limitations and strengths of the literature prior to exploring avenues of future research and implications for theory and clinical practice.

Methylation of the glucocorticoid receptor gene associated with depression in patients with acute coronary syndrome

OBJECTIVE

The present study investigated the longitudinal effects of NR3C1 1 F exon methylation on the risk of depression following ACS and treatment outcomes.

METHODS

In total, 969 patients admitted for recent ACS were recruited within 2 weeks of ACS; 711 of these patients were followed up at 1 year. Depressive disorder was diagnosed according to DSM-IV criteria and included prevalent depressive disorder at baseline and incident or persistent depressive disorder at follow-up based on depression status at the two examinations. Of the 378 baseline participants who were diagnosed with depression, 255 participated in a randomized double-blind placebo-controlled trial of escitalopram, while the remaining 123 were managed with the usual medical treatment for ACS.NR3C1 1 F exon methylation was measured using peripheral blood samples, and various demographic and clinical characteristics were assessed as covariates.

RESULTS

Higher NR3C1 1 F exon methylation levels were independently associated with prevalent depressive disorder at baseline but not with incident or persistent depressive disorder at follow-up based on logistic regression analyses adjusted for covariates. The effects of escitalopram on the remission of depressive symptoms was not influenced by NR3C1 1 F exon methylation status in ACS patients, but a placebo effect on the remission of depressive symptoms was observed, particularly in patients with lower methylation levels.

CONCLUSIONS

ACS patients with higher NR3C1 1 F exon methylation levels were at higher risk of developing depressive disorder within 2 weeks of ACS. Additionally, adequate antidepressant treatment may be effective for the remission of depressive symptoms regardless of NR3C1 1 F exon methylation status.

Epigenetics, maternal prenatal psychosocial stress, and infant mental health

This paper provides a summary of literature on epigenetic effects and infant health outcomes of maternal psychosocial stress during pregnancy. A search of literature yielded a large body of publications between 2008 and 2018. Relevant articles were selected, and additional sources were located from ancestry searches of reference lists. Results implicate maternal prenatal stress as a source of epigenetic mechanisms that affect fetal brain development and program risk for emotional dysregulation and mental disorders over a lifetime and across generations. Implications for nursing practice are explored at multiple levels of policy advocacy, public education, primary prevention, screening and intervention.

Effects of Interaction Between DRD4 Methylation and Prenatal Maternal Stress on Methylphenidate-Induced Changes in Continuous Performance Test Performance in Youth with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

Environmental factors may interact with genetic factors via the epigenetic process, and this interaction can contribute to inter-individual variability in the treatment response. The purpose of this study was to investigate the interaction effects between dopamine receptor D4 (DRD4) methylation and prenatal maternal stress on the methylphenidate (MPH) response of youth with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This study was an 8-week open-label trial of MPH that included 74 ADHD youth. We investigated the associations between MPH treatment response, which was defined as a score ≤2 on the Clinical Global Impressions-Improvement (CGI-I) scale, and the methylation of 28 cytosine-guanine dinucleotide (CpG) sites of DRD4. Additionally, the interaction effects between DRD4 methylation and prenatal maternal stress on changes in Continuous Performance Test (CPT) scores after MPH treatment were investigated.

RESULTS

Although there were no significant sites that showed significant association with treatment response, there was a significant interaction effect of the methylation of CpG7 and prenatal maternal stress on changes in omission errors of the CPT following treatment (p = 0.0001).

CONCLUSIONS

The present findings indicate that the interaction between methylation of CpG7 of DRD4 and prenatal maternal stress may be predictive of the treatment response to MPH in youth with ADHD.

A Methylome-Wide Association Study of Trajectories of Oppositional Defiant Behaviors and Biological Overlap With Attention Deficit Hyperactivity Disorder

In 671 mother-child (49% male) pairs from an epidemiological birth cohort, we investigated (a) prospective associations between DNA methylation (at birth) and trajectories (ages 7-13) of oppositional defiant disorder (ODD), and the ODD subdimensions of irritable and headstrong; (b) common biological pathways, indexed by DNA methylation, between ODD trajectories and attention deficit hyperactivity disorder (ADHD); (c) genetic influence on DNA methylation; and (d) prenatal risk exposure associations. Methylome-wide significant associations were identified for the ODD and headstrong, but not for irritable. Overlap analysis indicated biological correlates between ODD, headstrong, and ADHD. DNA methylation in ODD and headstrong was (to a degree) genetically influenced. DNA methylation associated with prenatal risk exposures of maternal anxiety (headstrong) and cigarette smoking (ODD and headstrong).

Glucocorticoid receptor gene (NR3C1) DNA methylation in association with trauma, psychopathology, transcript expression, or genotypic variation: A systematic review

The glucocorticoid receptor gene (NR3C1) is a critical component of the stress response system. Cytosine methylation of NR3C1 has been repeatedly associated with trauma and mental disorders, including major depression, post-traumatic stress disorder, anxiety, and personality disorders, suggesting that NR3C1 methylation may play a role in stress-related psychopathology. We systematically reviewed 55 studies examining NR3C1 DNA methylation in association with trauma exposure, psychopathology, gene expression, and/or common genetic variants. Overall, a number of NR3C1 CpG sites were significantly associated with trauma or psychopathology, but significant findings were often inconsistent across studies. This lack of consistency is likely influenced by significant methodological variability - experimentally and analytically - across studies. Selected common genetic variants show no significant effect on NR3C1 CpG methylation. In contrast, there was ample evidence linking increased methylation of NR3C1 to reduced expression of this gene. The inverse association between methylation and gene expression shown across eight out of ten studies supports the notion that methylation in the promoter region of NR3C1 is associated with transcriptional silencing.

NR3C1 hypermethylation in depressed and bullied adolescents

The disruption of key epigenetic processes during critical periods of brain development can increase an individual's vulnerability to psychopathology later in life. For instance, DNA methylation in the glucocorticoid receptor gene (NR3C1) in adulthood is known to be associated with early-life adversities and has been suggested to mediate the development of stress-related disorders. However, the association between NR3C1 methylation and the emergence of internalizing symptoms in childhood and adolescence has not been studied extensively. In the present report, we used saliva DNA from a cohort of Swedish adolescents (13-14 years old; N = 1149) to measure NR3C1 methylation in the exon 1F region. Internalizing psychopathological symptoms were assessed using the Center for Epidemiologic Studies Depression Scale for Children (CES-DC). We found that NR3C1 hypermethylation was cross-sectionally associated with high score for internalizing symptoms in the whole group as well as among the female participants. In addition, an analysis of social environmental stressors revealed that reports of bullied or lacking friends were significantly associated with NR3C1 hypermethylation. This cross-sectional association of NR3C1 exon 1F hypermethylation with internalizing psychopathology in adolescents, as well as with bullying and lack of friends are novel results in this field. Longitudinal studies are needed to address whether NR3C1 methylation mediates the link between social stressors and psychopathology in adolescence.

Longitudinal associations between glucocorticoid receptor methylation and late-life depression

It has been suggested that hypothalamus-pituitary-adrenal (HPA) axis dysregulation plays a role in the etiology of depression. HPA axis function is mediated by glucocorticoid receptors (GRs), which are influenced by epigenetic mechanisms (DNA methylation). The association between the DNA methylation of the GR gene (nuclear receptor subfamily 3, group C, member 1; NR3C1) and late-life depression as well as the role of NR3C1 methylation in the prediction of the incidence of depression have not yet been investigated. Therefore, we examined the independent and longitudinal effects of the methylation of three CpG sites in exon 1_F of NR3C1 on late-life depression using peripheral blood. In total, 732 Korean community residents aged ≥65 years were assessed; 521 individuals in this group without depression at baseline were followed 2 years later. The Geriatric Mental State Schedule was used to identify depression, and demographic and clinical covariates were evaluated. The effects of NR3C1 methylation (the individual methylation status of three CpG sites and their average values) on current and follow-up depression were calculated using a multivariate logistic regression model. Higher NR3C1 methylation levels at CpG 2 and 3 and the average methylation value were independently associated with the prevalence of depression at baseline. Additionally, a higher NR3C1 methylation level at CpG 2 was associated with depression incidence 2 years later in this population. These findings suggest an association between the methylation of NR3C1 exon 1_F, especially at CpG 2, and depression later in life.

Annual Research Review: DNA methylation as a mediator in the association between risk exposure and child and adolescent psychopathology

BACKGROUND

DNA methylation (DNAm) is a potential mechanism for propagating the effects of environmental exposures on child and adolescent mental health. In recent years, this field has experienced steady growth.

METHODS

We provide a strategic review of the current child and adolescent literature to evaluate evidence for a mediating role of DNAm in the link between environmental risks and psychopathological outcomes, with a focus on internalising and externalising difficulties.

RESULTS

Based on the studies presented, we conclude that there is preliminary evidence to support that (a) environmental factors, such as diet, neurotoxic exposures and stress, influence offspring DNAm, and that (b) variability in DNAm, in turn, is associated with child and adolescent psychopathology. Overall, very few studies have examined DNAm in relation to both exposures and outcomes, and almost all analyses have been correlational in nature.

CONCLUSIONS

DNAm holds potential as a biomarker indexing both environmental risk exposure and vulnerability for child psychopathology. However, the extent to which it may represent a causal mediator is not clear. In future, collection of prospective risk exposure, DNAm and outcomes - as well as functional characterisation of epigenetic findings - will assist in determining the role of DNAm in the link between risk exposure and psychopathology.

Glucocorticoid receptor gene methylation moderates the association of childhood trauma and cortisol stress reactivity

Exposure to childhood trauma (CT) has been linked to sustained dysregulations of major stress response systems, including findings of both exaggerated and attenuated hypothalamus-pituitary-adrenal (HPA) axis activity. Likewise, CT constitutes a common risk factor for a broad range of psychiatric conditions that involve distinct neuroendocrine profiles. In this study, we investigated the role of epigenetic variability in a stress-related gene as a potential mediator or moderator of such differential trajectories in CT survivors. For this, we screened adult volunteers for CT and recruited a healthy sample of 98 exposed (67 with mild-moderate, 31 with moderate-severe exposure) and 102 control individuals, with an equal number of males and females in each group. DNA methylation (DNA_M) levels of the glucocorticoid receptor exon 1F promoter (NR3C1-1F) at functionally relevant sites were analyzed via bisulfite pyrosequencing from whole blood samples. Participants were exposed to a laboratory stressor (Trier Social Stress Test) to assess salivary cortisol stress responses. The major finding of this study indicates that DNA_M in a biologically relevant region of NR3C1-1F moderates the specific direction of HPA-axis dysregulation (hypo- vs. hyperreactivity) in adults exposed to moderate-severe CT. Those trauma survivors with increased NR3C1-1F DNA_M displayed, on average, 10.4 nmol/l (62.3%) higher peak cortisol levels in response to the TSST compared to those with low DNA_M. In contrast, unexposed and mildly-moderately exposed individuals displayed moderately sized cortisol stress responses irrespective of NR3C1-1F DNA_M. Contrary to some prior work, however, our data provides no evidence for a direct association of CT and NR3C1-1F DNA_M status. According to this study, epigenetic changes of NR3C1-1F may provide a more in-depth understanding of the highly variable neuroendocrine and pathological sequelae of CT.

Healthy Foundations Study: a randomised controlled trial to evaluate biological embedding of early-life experiences

INTRODUCTION

Adverse early experiences are associated with long-lasting disruptions in physiology, development and health. These experiences may be 'biologically embedded' into molecular and genomic systems that determine later expressions of vulnerability. Most studies to date have not examined whether preventive interventions can potentially reverse biological embedding. The Nurse-Family Partnership (NFP) is an evidence-based intervention with demonstrated efficacy in improving prenatal health, parenting and child functioning. The Healthy Foundations Study is an innovative birth cohort which will evaluate the impact of the NFP on biological outcomes of mothers and their infants.

METHODS AND ANALYSIS

Starting in 2013, up to 400 pregnant mothers and their newborns were recruited from the British Columbia Healthy Connections Project-a randomised controlled trial of the NFP, and will be followed to child aged 2 years. Women were recruited prior to 28 weeks' gestation and then individually randomised to receive existing services (comparison group) or NFP plus existing services (intervention group). Hair samples are collected from mothers at baseline and 2 months post partum to measure physiological stress. Saliva samples are collected from infants during all visits for analyses of stress and immune function. Buccal swabs are collected from infants at 2 and 24 months to assess DNA methylation. Biological samples will be related to child outcome measures at age 2 years.

ETHICS AND DISSEMINATION

The study received ethical approval from seven research ethics boards. Findings from this study will be shared broadly with the research community through peer-reviewed publications, and conference presentations, as well as seminars with our policy partners and relevant healthcare providers. The outcomes of this study will provide all stakeholders with important information regarding how early adversity may lead to health and behavioural disparities and how these may be altered through early interventions.

TRIAL REGISTRATION NUMBER

NCT01672060; Pre-results.

Epigenetics in Personality Disorders: Today's Insights

Objective: Epigenetic mechanisms have been described in several mental disorders, such as mood disorders, anxiety disorders and schizophrenia. However, less is known about the influence of epigenetic mechanisms with regard to personality disorders (PD). Therefore, we conducted a literature review on existing original data with regards to epigenetic peculiarities in connection with personality disorders. Methods: Systematic literature review using PRISMA guidelines. Search was performed via NCBI PubMed by keywords and their combinations. Used search terms included "epigenetic," "methylation," "acetylation" plus designations of specified personality traits and disorders according to DSM-IV. Results: Search yielded in total 345 publications, 257 thereof with psychiatric topic, 72 on personality disorder or traits, 43 of which were in humans and epigenetic, 23 thereof were original studies. Lastly, 23 original publications fulfilled the intended search criteria and were included. Those are 13 studies on gene methylation pattern with aggressive, antisocial and impulsive traits, 9 with borderline personality disorder (BPD), and 2 with antisocial personality disorder (ASPD). The results of these studies showed significant associations of PD with methylation aberrances in system-wide genes and suggest evidence for epigenetic processes in the development of personality traits and personality disorders. Environmental factors, of which childhood trauma showed a high impact, interfered with many neurofunctional genes. Methylation alterations in ASPD and BPD repeatedly affected HTR2A, HTR3A, NR3C1, and MAOA genes. Summary: Epigenetic studies in PD seem to be a useful approach to elucidate the interaction of co-working risk factors in the pathogenesis of personality traits and disorders. However, the complexity of pathogenesis leads to divergent results and impedes an explicit interpretation. Differing methylation patterns within the selected PD could indicate subgroups which would benefit from patient-oriented therapeutic adjustments. They might play a major role in the future design and observation of early therapeutic intervention and thus could help to prevent severe dysfunctional conduct or full-blown personality disorder in risk subjects.

Dynamic stress-related epigenetic regulation of the glucocorticoid receptor gene promoter during early development: The role of child maltreatment

Epigenetics processes may play a vital role in the biological embedding of early environmental adversity and the development of psychopathology. Accumulating evidence suggests that maltreatment is linked to methylation of the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), which is a key regulator of the hypothalamus-pituitary-adrenal axis. However, prior work has been exclusively cross-sectional, greatly constraining our understanding of stress-related epigenetic processes over time. In the current study, we examined the effect of maltreatment and other adversity on change in NR3C1 methylation among at-risk preschoolers to begin to characterize within-child epigenetic changes during this sensitive developmental period. Participants were 260 preschoolers (3-5 years old, 53.8% female), including 51.5% with moderate to severe maltreatment in the past 6 months. Child protection records, semistructured interviews, and parent reports were used to assess child stress exposure. Methylation of exons 1D and 1F of NR3C1 via saliva DNA were measured at two time points approximately 6 months apart. Results indicate that maltreated children evidence higher baseline levels of NR3C1 methylation, significant decreases in methylation over time, and then at follow-up, lower levels of methylation, relative to nonmaltreated preschoolers. Findings from the current study highlight the complex nature of stress-related epigenetic processes during early development.

Methylation of the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), in maltreated and nonmaltreated children: Associations with behavioral undercontrol, emotional lability/negativity, and externalizing and internalizing symptoms

The present study examined the effect of various dimensions of child maltreatment (i.e., developmental timing of maltreatment, number of maltreatment subtypes, and chronicity of maltreatment) on methylation of the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), and investigated the associations between NR3C1 methylation and child outcomes. Participants included 534 children who attended a research summer camp program for school-aged maltreated (53.4%) and nonmaltreated (46.6%) children from low socioeconomic backgrounds. Results show that children with early onset maltreatment evidence significant hypermethylation compared to nonmaltreated children. Moreover, more maltreatment subtypes experienced and more chronic maltreatment are both related to greater NR3C1 hypermethylation. Findings also indicate that hypermethylation of NR3C1 is linked with a number of negative child outcomes including greater emotional lability-negativity, higher levels of ego undercontrol, more externalizing behavior, and greater depressive symptoms. Together, results highlight the role of methylation of NR3C1 in the effects of child maltreatment on the development of emotion dysregulation and psychopathology.

Neuroscience of Childhood Poverty: Evidence of Impacts and Mechanisms as Vehicles of Dialog With Ethics

Several studies have identified associations between poverty and development of self-regulation during childhood, which is broadly defined as those skills involved in cognitive, emotional, and stress self-regulation. These skills are influenced by different individual and contextual factors at multiple levels of analysis (i.e., individual, family, social, and cultural). Available evidence suggests that the influences of those biological, psychosocial, and sociocultural factors on emotional and cognitive development can vary according to the type, number, accumulation of risks, and co-occurrence of adverse circumstances that are related to poverty, the time in which these factors exert their influences, and the individual susceptibility to them. Complementary, during the past three decades, several experimental interventions that were aimed at optimizing development of self-regulation of children who live in poverty have been designed, implemented, and evaluated. Their results suggest that it is possible to optimize different aspects of cognitive performance and that it would be possible to transfer some aspects of these gains to other cognitive domains and academic achievement. We suggest that it is an important task for ethics, notably but not exclusively neuroethics, to engage in this interdisciplinary research domain to contribute analyses of key concepts, arguments, and interpretations. The specific evidence that neuroscience brings to the analyses of poverty and its implications needs to be spelled out in detail and clarified conceptually, notably in terms of causes of and attitudes toward poverty, implications of poverty for brain development, and for the possibilities to reduce and reverse these effects.

Anxiety and Epigenetics

Anxiety disorders are highly prevalent psychiatric disorders often comorbid with depression and substance abuse. Twin studies have shown that anxiety disorders are moderately heritable. Yet, genome-wide association studies (GWASs) have failed to identify gene(s) significantly associated with diagnosis suggesting a strong role for environmental factors and the epigenome. A number of anxiety disorder subtypes are considered "stress related." A large focus of research has been on the epigenetic and anxiety-like behavioral consequences of stress. Animal models of anxiety-related disorders have provided strong evidence for the role of stress on the epigenetic control of the hypothalamic-pituitary-adrenal (HPA) axis and of stress-responsive brain regions. Neuroepigenetics may continue to explain individual variation in susceptibility to environmental perturbations and consequently anxious behavior. Behavioral and pharmacological interventions aimed at targeting epigenetic marks associated with anxiety may prove fruitful in developing treatments.

Childhood adversity and epigenetic regulation of glucocorticoid signaling genes: Associations in children and adults

Early childhood experiences have lasting effects on development, including the risk for psychiatric disorders. Research examining the biologic underpinnings of these associations has revealed the impact of childhood maltreatment on the physiologic stress response and activity of the hypothalamus-pituitary-adrenal axis. A growing body of literature supports the hypothesis that environmental exposures mediate their biological effects via epigenetic mechanisms. Methylation, which is thought to be the most stable form of epigenetic change, is a likely mechanism by which early life exposures have lasting effects. We present recent evidence related to epigenetic regulation of genes involved in hypothalamus-pituitary-adrenal axis regulation, namely, the glucocorticoid receptor gene (nuclear receptor subfamily 3, group C, member 1 [NR3C1]) and FK506 binding protein 51 gene (FKBP5), after childhood adversity and associations with risk for psychiatric disorders. Implications for the development of interventions and future research are discussed.

Methylation of the leukocyte glucocorticoid receptor gene promoter in adults: associations with early adversity and depressive, anxiety and substance-use disorders

Early adversity increases risk for developing psychopathology. Epigenetic modification of stress reactivity genes is a likely mechanism contributing to this risk. The glucocorticoid receptor (GR) gene is of particular interest because of the regulatory role of the GR in hypothalamic-pituitary-adrenal (HPA) axis function. Mounting evidence suggests that early adversity is associated with GR promoter methylation and gene expression. Few studies have examined links between GR promoter methylation and psychopathology, and findings to date have been mixed. Healthy adult participants (N=340) who were free of psychotropic medications reported on their childhood experiences of maltreatment and parental death and desertion. Lifetime depressive and anxiety disorders and past substance-use disorders were assessed using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Methylation of exon 1F of the GR gene (NR3C1) was examined in leukocyte DNA via pyrosequencing. On a separate day, a subset of the participants (n=231) completed the dexamethasone/corticotropin-releasing hormone (Dex/CRH) test. Childhood adversity and a history of past substance-use disorder and current or past depressive or anxiety disorders were associated with lower levels of NR3C1 promoter methylation across the region as a whole and at individual CpG sites (P<0.05). The number of adversities was negatively associated with NR3C1 methylation in participants with no lifetime disorder (P=0.018), but not in those with a lifetime disorder. GR promoter methylation was linked to altered cortisol responses to the Dex/CRH test (P<0.05). This study presents evidence of reduced methylation of NR3C1 in association with childhood maltreatment and depressive, anxiety and substance-use disorders in adults. This finding stands in contrast to our prior work, but is consistent with emerging findings, suggesting complexity in the regulation of this gene.