Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities

Polygene by environment interactions predicting depressive outcomes

Depression is a major public health problem with a continued need to uncover its etiology. Current models of depression contend that gene-by-environment (G × E) interactions influence depression risk, and further, that depression is polygenic. Thus, recent models have emphasized two polygenic approaches: a hypothesis-driven multilocus genetic profile score (MGPS; "MGPS × E") and a polygenic risk score (PRS; "PRS × E") derived from genome-wide association studies (GWAS). This review for the first time synthesizes current knowledge on polygene by environment "P × E" interaction research predicting primarily depression-related outcomes, and in brief, neurobiological outcomes. The "environment" of focus in this project is stressful life events. It further discusses findings in the context of differential susceptibility and diathesis-stress theories-two major theories guiding G × E work. This synthesis indicates that, within the MGPS literature, polygenic scores based on the serotonin system, the HPA axis, or across multiple systems, interact with environmental stress exposure to predict outcomes at multiple levels of analyses and most consistently align with differential susceptibility theory. Depressive outcomes are the most studied, but neuroendocrine, and neuroimaging findings are observed as well. By contrast, vast methodological differences between GWAS-based PRS studies contribute to mixed findings that yield inconclusive results.

Nucleus accumbens myocyte enhancer factor 2C mediates the maintenance of peripheral nerve injury-induced physiological and behavioral maladaptations

ABSTRACT

Preclinical and clinical work has demonstrated altered plasticity and activity in the nucleus accumbens (NAc) under chronic pain states, highlighting critical therapeutic avenues for the management of chronic pain conditions. In this study, we demonstrate that myocyte enhancer factor 2C (MEF2C), a master regulator of neuronal activity and plasticity, is repressed in NAc neurons after prolonged spared nerve injury (SNI). Viral-mediated overexpression of Mef2c in NAc neurons partially ameliorated sensory hypersensitivity and emotional behaviors in mice with SNI, while also altering transcriptional pathways associated with synaptic signaling. Mef2c overexpression also reversed SNI-induced potentiation of phasic dopamine release and neuronal hyperexcitability in the NAc. Transcriptional changes induced by Mef2c overexpression were different than those observed after desipramine treatment, suggesting a mechanism of action different from antidepressants. Overall, we show that interventions in MEF2C-regulated mechanisms in the NAc are sufficient to disrupt the maintenance of chronic pain states, providing potential new treatment avenues for neuropathic pain.

Association between serum catecholamine levels and VNTR polymorphism in the promoter region of the monoamine oxidase A gene in forensic autopsy cases

Monoamine oxidase A (MAOA) catalyzes oxidative deamination of catecholamines. A functional variable number tandem repeat (VNTR) polymorphism in the promoter region of the MAOA gene has been previously reported. In the present study, we measured serum adrenaline (Adr), noradrenaline (Nad), and dopamine (DA) levels in 90 male and 34 female Japanese autopsy cases in which amphetamines or psychotropic drugs were not detected.We examined the frequencies of MAOA-uVNTR alleles in these cases and investigated the effects of the MAOA-uVNTR polymorphism on serum Adr, Nad, and DA levels. Evaluation indicated no significant association between MAOA-uVNTR polymorphism and serum Adr, Nad, or DA levels in males, although a significant association between MAOA-uVNTR polymorphism and serum Adr and DA levels were observed in females. Females with the 3/3 genotype had higher serum Adr and DA levels than those with a 4-repeat allele (3/4 and 4/4 genotypes) (p = 0.048 and 0.020, respectively). There was no significant association between MAOA-uVNTR polymorphism and serum Nad levels in females. The present study indicates that MAOA-uVNTR polymorphism influences serum Adr and DA levels only in females.

Going Beyond Childhood and Gender-Based Violence: Epigenetic Modifications and Inheritance

Being exposed to childhood or gender-based violence is associated with subsequent adverse events in individual lives. Not only can it cause psychological distress but violence survivors suffer from a range of long-term adverse health outcomes, including higher morbidity, higher mortality, and higher risk of chronic diseases. Epigenetics may be involved in the determinisms of these long-term detrimental effects. A large body of evidence supports this biological mechanism to explain violence-related health impairment in the long term. However, studies specifically focusing on violence are scant and nonunivocal. Epigenetic modifications of genes involved in stress response and in the hypothalamus-pituitary-adrenal axis regulation are the most commonly and consistently reported. Promising evidence also emerged for the use of epigenetic clocks. Finally, although very limited, there is evidence supporting the notion that long-term health impairment may be transmitted from one generation to the other. Overall, despite promising, available evidence is yet incomplete. The overlap with pure psychological mechanisms of health impairment exposes the findings to confounders and hampers strong conclusions. Based on a literature search on PubMed/Embase, our narrative review aims to illustrate the evidence concerning the potential bond between epigenetics and violence, including also possible impacts on later generations. The goal is to encourage further research to help the development of a more holistic approach for such a vulnerable and often neglected population. Further research is warranted to precisely disentangle the role of epigenetics in mediating the long-term health impairment associated with childhood or gender-based violence. Advances in this area may open new avenues of treatment. Epigenetic modifications may indeed be reversible and could be an attractive therapeutic target to minimize the long-term consequences of childhood or gender-based violence.

Does biological age mediate the relationship between childhood adversity and depression? Insights from the Detroit Neighborhood Health Study

The link between childhood adversity and adulthood depression is well-established; however, the underlying mechanisms are still being explored. Recent research suggests biological age may mediate the relationship between childhood adversity and depression in later life. This study examines if biological age mediates the relationship between childhood adversity and depression symptoms using an expanded set of biological age measures in an urban population-based cohort. Data from waves 1-3 of the Detroit Neighborhood Health Study (DNHS) were used in this analysis. Questions about abuse during childhood were coded to form a childhood adversity score similar to the Adverse Childhood Experience measure. Multiple dimensions of biological age, defined as latent variables, were considered, including systemic biological age (GrimAge, PhenoAge), epigenetic age (Horvath, SkinBlood), and immune age (cytomegalovirus, herpes simplex virus type 1, C-reactive protein, interleukin-6). Depression symptoms, modeled as a latent variable, were captured through the Patient Health Questionnaire-9 (PHQ-9). Models were adjusted for age, gender, race, parent education, and past depressive symptoms. Total and direct effects of childhood adversity on depression symptoms and indirect effects mediated by biological age were estimated. For total and direct effects, we observed a dose-dependent relationship between cumulative childhood adversity and depression symptoms, with emotional abuse being particularly influential. However, contrary to prior studies, in this sample, we found few direct effects of childhood adversity on biological age or biological age on depression symptoms and no evidence of mediation through the measures of biological age considered in this study. Further research is needed to understand how childhood maltreatment experiences are embodied to influence health and wellness.

MAOA methylation is associated with impulsive and antisocial behaviour: dependence on allelic variation, family environment and diet

Congenital absence of monoamine oxidase A (MAO-A) activity predisposes to antisocial impulsive behaviour, and the MAOA uVNTR low-expressing genotype (MAOA-L) together with childhood maltreatment is associated with similar phenotypes in males. A possible explanation of how family environment may lead to such behaviour involves DNA methylation. We have assessed MAOA methylation and impulsive/antisocial behaviour in 121 males from the Estonian Children Personality Behaviour and Health Study. Of the 12 CpG sites measured, methylation levels at the locus designated CpG3 were significantly lower in subjects with antisocial behaviour involving police contact. CpG3 methylation was lower in subjects with alcohol use disorder by age 25, but only in MAOA-H genotype. No correlation between MAOA CpG3 methylation levels and adaptive impulsivity was found at age 15, but in MAOA-L genotype a positive correlation appeared by age 18. By age 25, this positive correlation was no longer observed in subjects with better family relationships but had increased further with experience of adversity within the family. MAOA CpG3 methylation had different developmental dynamics in relation to maladaptive impulsivity. At age 18, a positive correlation was observed in MAOA-L genotype with inferior family relationships and a negative correlation was found in MAOA-H with superior home environment; both of these associations had disappeared by age 25. CpG3 methylation was associated with dietary intake of several micronutrients, most notable was a negative correlation with the intake of zinc, but also with calcium, potassium and vitamin E; a positive correlation was found with intake of phosphorus. In conclusion, MAOA CpG3 methylation is related to both maladaptive and adaptive impulsivity in adolescence in MAOA-L males from adverse home environment. By young adulthood, this relationship with maladaptive impulsivity had disappeared but with adaptive impulsivity strengthened. Thus, MAOA CpG3 methylation may serve as a marker for adaptive developmental neuroplasticity in MAOA-L genotype. The mechanisms involved may include dietary factors.

Epigenetic regulation in major depression and other stress-related disorders: molecular mechanisms, clinical relevance and therapeutic potential

Major depressive disorder (MDD) is a chronic, generally episodic and debilitating disease that affects an estimated 300 million people worldwide, but its pathogenesis is poorly understood. The heritability estimate of MDD is 30-40%, suggesting that genetics alone do not account for most of the risk of major depression. Another factor known to associate with MDD involves environmental stressors such as childhood adversity and recent life stress. Recent studies have emerged to show that the biological impact of environmental factors in MDD and other stress-related disorders is mediated by a variety of epigenetic modifications. These epigenetic modification alterations contribute to abnormal neuroendocrine responses, neuroplasticity impairment, neurotransmission and neuroglia dysfunction, which are involved in the pathophysiology of MDD. Furthermore, epigenetic marks have been associated with the diagnosis and treatment of MDD. The evaluation of epigenetic modifications holds promise for further understanding of the heterogeneous etiology and complex phenotypes of MDD, and may identify new therapeutic targets. Here, we review preclinical and clinical epigenetic findings, including DNA methylation, histone modification, noncoding RNA, RNA modification, and chromatin remodeling factor in MDD. In addition, we elaborate on the contribution of these epigenetic mechanisms to the pathological trait variability in depression and discuss how such mechanisms can be exploited for therapeutic purposes.

Maternal-infant interaction quality is associated with child NR3C1 CpG site methylation at 7 years of age

OBJECTIVE

Infancy is both a critical window for hypothalamic-pituitary-adrenal (HPA) axis development, and a sensitive period for social-emotional influences. We hypothesized that the social-emotional quality of maternal-infant interactions are associated with methylation of HPA-axis gene NR3C1 later in childhood.

METHODS

Using a subsample of 114 mother-infant pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC), linear regression models were created to predict variance in methylation of seven selected CpG sites from NR3C1 in whole blood at age 7 years, including the main predictor variable of the first principal component score of observed maternal-infant interaction quality (derived from the Thorpe Interaction Measure at 12 months of age) and covariates of cell-type proportion, maternal financial difficulties and marital status at 8 months postnatal, child birthweight, and sex.

RESULTS

CpG site cg27122725 methylation was negatively associated with warmer, more positive maternal interaction with her infant (β = 0.19, p = .02, q = 0.13). In sensitivity analyses, the second highest quartile of maternal behavior (neutral, hesitant behavior) was positively associated with cg12466613 methylation. The other five CpG sites were not significantly associated with maternal-infant interaction quality.

CONCLUSIONS

Narrow individual variation of maternal interaction with her infant is associated with childhood methylation of two CpG sites on NR3C1 that may be particularly sensitive to environmental influences. Infancy may be a sensitive period for even small influences from the social-emotional environment on the epigenetic determinants of HPA-axis function.

The associations between DNA methylation and depression: A systematic review and meta-analysis

BACKGROUND

Growing evidence suggests that epigenetic modification is vital in biological processes of depression. Findings from studies exploring the associations between DNA methylation and depression have been inconsistent.

METHODS

A systematical search of EMBASE, PubMed, Web of Science, and PsycINFO databases was conducted to include studies focusing on the associations between DNA methylation and depression (up to November 1st 2021) according to PRISMA guidelines with registration in PROSPERO (CRD42021288664).

RESULTS

A total of 47 studies met inclusion criteria and 31 studies were included in the meta-analysis. This meta-analysis found that genes hypermethylation, including BDNF (OR: 1.15, 95%CI: 1.01-1.32, I² = 90 %), and NR3C1 (OR: 1.43, 95%CI: 1.09-1.87, I² = 88 %) was associated with increased risk of depression. Significant association of SLC6A4 hypermethylation with depression was only found in the subgroup of using original data (OR: 1.09, 95%CI: 1.01-1.19, I² = 52 %). BDNF hypermethylation could increase the risk of depression only in the Asian population (OR: 1.18, 95%CI: 1.01-1.40, I² = 91 %), and significant associations of NR3C1 hypermethylation with depression were found in the group for depressive symptoms (OR: 1.34, 95%CI: 1.08-1.67, I² = 85 %), but not for depressive disorder (OR: 1.89, 95%CI: 0.54-6.55, I² = 94 %).

LIMITATIONS

More studies are needed to explore the factors that might influence the estimates owing to the contextual heterogeneity of the pooling of included studies.

CONCLUSIONS

It is noted that DNA hypermethylation, namely BDNF and NR3C1, is associated with increased risk of depression. The findings in this study could provide some material evidence for preventing and diagnosing of depression.

The Biology of Stress Intolerance in Patients with Chronic Pain—State of the Art and Future Directions

Stress has been consistently linked to negative impacts on physical and mental health. More specifically, patients with chronic pain experience stress intolerance, which is an exacerbation or occurrence of symptoms in response to any type of stress. The pathophysiological mechanisms underlying this phenomenon remain unsolved. In this state-of-the-art paper, we summarised the role of the autonomic nervous system (ANS) and hypothalamus-pituitary-adrenal (HPA) axis, the two major stress response systems in stress intolerance. We provided insights into such mechanisms based on evidence from clinical studies in both patients with chronic pain, showing dysregulated stress systems, and healthy controls supported by preclinical studies, highlighting the link between these systems and symptoms of stress intolerance. Furthermore, we explored the possible regulating role for (epi)genetic mechanisms influencing the ANS and HPA axis. The link between stress and chronic pain has become an important area of research as it has the potential to inform the development of interventions to improve the quality of life for individuals living with chronic pain. As stress has become a prevalent concern in modern society, understanding the connection between stress, HPA axis, ANS, and chronic health conditions such as chronic pain is crucial to improve public health and well-being.

Early life adversity across different cell- types in the brain

Early life adversity (ELA)- which includes physical, psychological, emotional, and sexual abuse is one of the most common predictors to diverse psychopathologies later in adulthood. As ELA has a lasting impact on the brain at a developmental stage, recent findings from the field highlighted the specific contributions of different cell types to ELA and their association with long lasting consequences. In this review we will gather recent findings describing morphological, transcriptional and epigenetic alterations within neurons, glia and perineuronal nets and their associated cellular subpopulation. The findings reviewed and summarized here highlight important mechanisms underlying ELA and point to therapeutic approaches for ELA and related psychopathologies later in life.

Effect of MAOA DNA Methylation on Human in Vivo Protein Expression Measured by [11C]harmine Positron Emission Tomography

BACKGROUND

Epigenetic modifications like DNA methylation are understood as an intermediary between environmental factors and neurobiology. Cerebral monoamine oxidase A (MAO-A) levels are altered in depression, as are DNA methylation levels within the MAOA gene, particularly in the promoter/exon I/intron I region. An effect of MAOA methylation on peripheral protein expression was shown, but the extent to which methylation affects brain MAO-A levels is not fully understood.

METHODS

Here, the influence of MAOA promoter/exon I/intron I region DNA methylation on global MAO-A distribution volume (VT), an index of MAO-A density, was assessed via [11C]harmine positron emission tomography in 22 patients (14 females) suffering from seasonal affective disorder and 30 healthy controls (17 females).

RESULTS

No significant influence of MAOA DNA methylation on global MAO-A VT was found, despite correction for health status, sex, season, and MAOA variable number of tandem repeat genotype. However, season affected average methylation in women, with higher levels in spring and summer (Puncorr = .03). We thus did not find evidence for an effect of MAOA DNA methylation on brain MAO-A VT.

CONCLUSIONS

In contrast to a previous study demonstrating an effect of methylation of a MAOA promoter region located further 5' on brain MAO-A, MAOA methylation of the region assessed here appears to affect brain protein levels to a limited extent at most. The observed effect of season on methylation levels is in accordance with extensive evidence for seasonal effects within the serotonergic system.

CLINICALTRIALS.GOV IDENTIFIER

NCT02582398 (https://clinicaltrials.gov/ct2/show/NCT02582398).

Methylation and expression of glucocorticoid receptor exon-1 variants and FKBP5 in teenage suicide-completers

A dysregulated hypothalamic-pituitary-adrenal (HPA) axis has repeatedly been demonstrated to play a fundamental role in psychiatric disorders and suicide, yet the mechanisms underlying this dysregulation are not clear. Decreased expression of the glucocorticoid receptor (GR) gene, which is also susceptible to epigenetic modulation, is a strong indicator of impaired HPA axis control. In the context of teenage suicide-completers, we have systematically analyzed the 5'UTR of the GR gene to determine the expression levels of all GR exon-1 transcript variants and their epigenetic state. We also measured the expression and the epigenetic state of the FK506-binding protein 51 (FKBP5/FKBP51), an important modulator of GR activity. Furthermore, steady-state DNA methylation levels depend upon the interplay between enzymes that promote DNA methylation and demethylation activities, thus we analyzed DNA methyltransferases (DNMTs), ten-eleven translocation enzymes (TETs), and growth arrest- and DNA-damage-inducible proteins (GADD45). Focusing on both the prefrontal cortex (PFC) and hippocampus, our results show decreased expression in specific GR exon-1 variants and a strong correlation of DNA methylation changes with gene expression in the PFC. FKBP5 expression is also increased in both areas suggesting a decreased GR sensitivity to cortisol binding. We also identified aberrant expression of DNA methylating and demethylating enzymes in both brain regions. These findings enhance our understanding of the complex transcriptional regulation of GR, providing evidence of epigenetically mediated reprogramming of the GR gene, which could lead to possible epigenetic influences that result in lasting modifications underlying an individual's overall HPA axis response and resilience to stress.

Association between child maltreatment and depressive symptoms in emerging adulthood: The mediating and moderating roles of DNA methylation

Prospective studies suggest that child maltreatment substantially increases the risk for depression in adulthood. However, the mechanisms underlying this association require further elucidation. In recent years, DNA methylation has emerged as a potential mechanism by which maltreatment experiences (a) could partly explain the emergence or aggravation of depressive symptoms (i.e., mediation) and/or (b) could increase (or decrease) the risk for depressive symptoms (i.e., moderation). The present study tested whether the methylation levels of nine candidate genes mediated and/or moderated the association between maltreatment experiences in childhood and depressive symptoms in emerging adulthood. The sample comprised 156 men aged between 18 and 35 years. Maltreatment experiences and depressive symptoms were assessed retrospectively using self-reported questionnaires. Methylation levels of nine candidate genes (COMT, FKBP5, IL6, IL10, MAOA, NR3C1, OXTR, SLC6A3 and SLC6A4), previously reported to be sensitive to early-life stress, were quantified from saliva samples. Maltreatment experiences in childhood were significantly associated with depressive symptoms in emerging adulthood. Both maltreatment experiences and depressive symptoms were associated with the methylation levels of two genomic sites, which cumulatively, but not individually, explained 16% of the association between maltreatment experiences in childhood and depressive symptoms in emerging adulthood. Moreover, maltreatment experiences in childhood interacted with the methylation levels of fourteen genomic sites, which cumulatively, but not individually, modulated the level of depressive symptoms in young male adults who were maltreated as children. However, none of these effects survived multiple testing correction. These findings bring attention to the cumulative effects of DNA methylation measured in several candidate genes on the risk of reporting depressive symptoms following maltreatment experiences in childhood. Nonetheless, future studies need to clarify the robustness of these putative cumulative effects in larger samples and longitudinal cohorts.

Neuroendocrine pathogenesis of perimenopausal depression

With the development of social economics and the increase of working pressure, more and more women are suffering from long-term serious stress and showing symptoms of perimenopausal depression (PMD). The incidence rate of PMD is increasing, and the physical and mental health are seriously affected. However, due to the lack of accurate knowledge of pathophysiology, its diagnosis and treatment cannot be accurately executed. By consulting the relevant literature in recent years, this paper elaborates the neuroendocrine mechanism of perimenopausal depression from the aspects of epigenetic changes, monoamine neurotransmitter and receptor hypothesis, glial cell-induced neuroinflammation, estrogen receptor, interaction between HPA axis and HPG axis, and micro-organism-brain gut axis. The purpose is to probe into new ways of treatment of PMD by providing new knowledge about the neuroendocrine mechanism and treatment of PMD.

Are the epigenetic changes predictive of therapeutic efficacy for psychiatric disorders? A translational approach towards novel drug targets

The etiopathogenesis of mental disorders is not fully understood and accumulating evidence support that clinical symptomatology cannot be assigned to a single gene mutation, but it involves several genetic factors. More specifically, a tight association between genes and environmental risk factors, which could be mediated by epigenetic mechanisms, may play a role in the development of mental disorders. Several data suggest that epigenetic modifications such as DNA methylation, post-translational histone modification and interference of microRNA (miRNA) or long non-coding RNA (lncRNA) may modify the severity of the disease and the outcome of the therapy. Indeed, the study of these mechanisms may help to identify patients particularly vulnerable to mental disorders and may have potential utility as biomarkers to facilitate diagnosis and treatment of psychiatric disorders. This article summarizes the most relevant preclinical and human data showing how epigenetic modifications can be central to the therapeutic efficacy of antidepressant and/or antipsychotic agents, as possible predictor of drugs response.

Epigenetics in depression and gut-brain axis: A molecular crosstalk

Gut-brain axis is a dynamic, complex, and bidirectional communication network between the gut and brain. Changes in the microbiota-gut-brain axis are responsible for developing various metabolic, neurodegenerative, and neuropsychiatric disorders. According to clinical and preclinical findings, the gut microbiota is a significant regulator of the gut-brain axis. In addition to interacting with intestinal cells and the enteric nervous system, it has been discovered that microbes in the gut can modify the central nervous system through metabolic and neuroendocrine pathways. The metabolites of the gut microbiome can modulate a number of diseases by inducing epigenetic alteration through DNA methylation, histone modification, and non-coding RNA-associated gene silencing. Short-chain fatty acids, especially butyrate, are well-known histone deacetylases inhibitors. Similarly, other microbial metabolites such as folate, choline, and trimethylamine-N-oxide also regulate epigenetics mechanisms. Furthermore, various studies have revealed the potential role of microbiome dysbiosis and epigenetics in the pathophysiology of depression. Hence, in this review, we have highlighted the role of gut dysbiosis in epigenetic regulation, causal interaction between host epigenetic modification and the gut microbiome in depression and suggest microbiome and epigenome as a possible target for diagnosis, prevention, and treatment of depression.

Estrogen receptors mediate the antidepressant effects of aerobic exercise: A possible new mechanism

Purpose

This study aimed to examine whether aerobic exercise exerts mood-modulating effects through an estrogen signaling mechanism.

Method

The experiment was divided into two parts. The first part is to compare the three modeling methods to obtain the most obvious method of depression-like phenotype for further study in the second part. The first part of ovariectomized rats (age, 13 weeks) was tested when rats were 14 or 22 weeks old or in the sixth week after 3 weeks of chronic restraint stress. The second part was to treat the animals with the most obvious depression-like phenotype in different ways, placebo treatment or estradiol (E2) replacement therapy was administered, aerobic training, or estrogen receptor antagonist treatment. The cognitive (Barnes maze and 3-chamber social tests), anxiety-like (open-field and elevated plus maze tests) and depression-like (sucrose preference and forced swim tests) behaviors of rats in both parts were analyzed to study the effects of estrogen depletion and aerobic exercise.

Results

Rats did not develop depressive symptoms immediately after ovariectomy, however, the symptoms became more pronounced with a gradual decrease in ovarian hormone levels. Compared with the placebo or control groups, the exercise and E2 groups showed improved performance in all behavioral test tasks, and the antidepressant effects of aerobic exercise were comparable to those of estrogen. Moreover, the estrogen receptor antagonist has markedly inhibited the antidepressant effects of aerobic exercise.

Conclusion

Estrogen receptors may mediate the antidepressant effects of aerobic exercise. In addition, an increasingly fragile ovarian hormonal environment may underlies chronic restraint stress-induced depression.

DNA Methylation in Depression and Depressive-Like Phenotype: Biomarker or Target of Pharmacological Intervention?

Major depressive disorder (MDD) is a debilitating psychiatric disorder, the third leading global cause of disability. Regarding aetiopathogenetic mechanisms involved in the onset of depressive disorders, the interaction between genetic vulnerability traits and environmental factors is believed to play a major role. Although much is still to be elucidated about the mechanisms through which the environment can interact with genetic background shaping the disease risk, there is a general agreement about a key role of epigenetic marking. In this narrative review, we focused on the association between changes in DNA methylation patterns and MDD or depressive-like phenotype in animal models, as well as mechanisms of response to antidepressant drugs. We discussed studies presenting DNA methylation changes at specific genes of interest and profiling analyses in both patients and animal models of depression. Overall, we collected evidence showing that DNA methylation could not only be considered as a promising epigenetic biomarker of pathology but could also help in predicting antidepressant treatment efficacy. Finally, we discussed the hypothesis that specific changes in DNA methylation signature could play a role in aetiopathogenetic processes as well as in the induction of antidepressant effect.

Depressive disorder and antidepressants from an epigenetic point of view

Depressive disorder is a complex, heterogeneous disease that affects approximately 280 million people worldwide. Environmental, genetic, and neurobiological factors contribute to the depressive state. Since the nervous system is susceptible to shifts in activity of epigenetic modifiers, these allow for significant plasticity and response to rapid changes in the environment. Among the most studied epigenetic modifications in depressive disorder is DNA methylation, with findings centered on the brain-derived neurotrophic factor gene, the glucocorticoid receptor gene, and the serotonin transporter gene. In order to identify biomarkers that would be useful in clinical settings, for diagnosis and for treatment response, further research on antidepressants and alterations they cause in the epigenetic landscape throughout the genome is needed. Studies on cornerstone antidepressants, such as selective serotonin reuptake inhibitors, selective serotonin and norepinephrine reuptake inhibitors, norepinephrine, and dopamine reuptake inhibitors and their effects on depressive disorder are available, but systematic conclusions on their effects are still hard to draw due to the highly heterogeneous nature of the studies. In addition, two novel drugs, ketamine and esketamine, are being investigated particularly in association with treatment of resistant depression, which is one of the hot topics of contemporary research and the field of precision psychiatry.

Can epigenetics shine a light on the biological pathways underlying major mental disorders?

A significant proportion of the global burden of disease can be attributed to mental illness. Despite important advances in identifying risk factors for mental health conditions, the biological processing underlying causal pathways to disease onset remain poorly understood. This represents a limitation to implement effective prevention and the development of novel pharmacological treatments. Epigenetic mechanisms have emerged as mediators of environmental and genetic risk factors which might play a role in disease onset, including childhood adversity (CA) and cannabis use (CU). Particularly, human research exploring DNA methylation has provided new and promising insights into the role of biological pathways implicated in the aetio-pathogenesis of psychiatric conditions, including: monoaminergic (Serotonin and Dopamine), GABAergic, glutamatergic, neurogenesis, inflammatory and immune response and oxidative stress. While these epigenetic changes have been often studied as disease-specific, similarly to the investigation of environmental risk factors, they are often transdiagnostic. Therefore, we aim to review the existing literature on DNA methylation from human studies of psychiatric diseases (i) to identify epigenetic modifications mapping onto biological pathways either transdiagnostically or specifically related to psychiatric diseases such as Eating Disorders, Post-traumatic Stress Disorder, Bipolar and Psychotic Disorder, Depression, Autism Spectrum Disorder and Anxiety Disorder, and (ii) to investigate a convergence between some of these epigenetic modifications and the exposure to known risk factors for psychiatric disorders such as CA and CU, as well as to other epigenetic confounders in psychiatry research.

Sex Differences in Depression Caused by Early Life Stress and Related Mechanisms

Depression is a common psychiatric disease caused by various factors, manifesting with continuous low spirits, with its precise mechanism being unclear. Early life stress (ELS) is receiving more attention as a possible cause of depression. Many studies focused on the mechanisms underlying how ELS leads to changes in sex hormones, neurotransmitters, hypothalamic pituitary adrenocortical (HPA) axis function, and epigenetics. The adverse effects of ELS on adulthood are mainly dependent on the time window when stress occurs, sex and the developmental stage when evaluating the impacts. Therefore, with regard to the exact sex differences of adult depression, we found that ELS could lead to sex-differentiated depression through multiple mechanisms, including 5-HT, sex hormone, HPA axis, and epigenetics.

Hypomethylation of monoamine oxidase A promoter/exon 1 region is associated with temper outbursts in Prader-Willi syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a rare neurodevelopmental disorder caused by the absence of paternally expressed and maternally imprinted genes on chromosome 15q 11.2-13. It is associated with a certain behavioural phenotype, especially temper outbursts with verbal and physical aggression towards others. Recent studies show a promising therapeutic effect of serotonin reuptake inhibitors like sertraline on frequency and intensity of outbursts. Monoamine oxidase A (MAOA) (X p11.23) plays a crucial role in the metabolism of monoamines. Dysregulation in methylation of the CpG island spanning the promoter region and exon 1 of MAOA is implicated in impulsive and aggressive behaviour.

METHODS

In the present study, methylation rates of CpG dinucleotides in the MAOA promoter and exon 1 region were determined from DNA derived from whole blood samples of PWS patients (n = 32) and controls (n = 14) matched for age, sex and BMI via bisulfite sequencing. PWS patients were grouped into those showing temper outbursts, and those who do not.

RESULTS

Overall, PWS patients show a significant lower methylation rate at the promoter/exon 1 region than healthy controls in both sexes. Furthermore, PWS patients, male as well female with temper outbursts show a significant lower methylation rate than those without temper outbursts (p < 0.001 and p = 0.006).

CONCLUSION

The MAOA promoter/exon 1 region methylation seems to be dysregulated in PWS patients in sense of a hypomethylation, especially in those suffering from temper outbursts. This dysregulation probably plays a crucial role in the pathophysiology of temper outbursts in PWS.

Epigenetic Determinants of Racial Disparity in Breast Cancer: Looking beyond Genetic Alterations

Simple Summary

A substantial disparity in breast cancer incidence and mortality exists between African American (AA) and European American (EA) women. However, the basis for these disparities is poorly understood. In this article, we describe that gene–environment interactions mediated through epigenetic modifications may play a significant role in racial disparities in BC incidence and outcomes. Our in silico analyses and an in-depth literature survey suggest that there exists a significant difference in epigenetic patterns between AA and EA women with breast cancer. Herein, we describe the environmental factors that contribute to these epigenetic changes, which may underlie the disparate racial burden in patients with breast cancer. We suggest that AA women with higher basal epigenetic changes, may have higher pre-disposition to cancer onset, and an aggressive disease course. Pre-existing racial differences in epigenetic profiles of breast tissues raises the possibility of examining these profiles for early diagnosis.

Abstract

Breast cancer (BC) is the most commonly diagnosed cancer in women. Despite advancements in BC screening, prevention, and treatment, BC incidence and mortality remain high among African American (AA) women. Compared with European American (EA) women, AA women tend to be diagnosed with more advanced and aggressive tumors and exhibit worse survival outcomes. Most studies investigating the determinants of racial disparities in BC have focused on genetic factors associated with African ancestry. However, various environmental and social stressors over an individual’s life course can also shape racial stratification in BC. These social and environmental exposures result in long-term changes in gene expression mediated by epigenetic mechanisms. Epigenetics is often portrayed as an intersection of socially patterned stress and genetic expression. The enduring nature of epigenetic changes makes them suitable for studying the effects of different environmental exposures over an individual’s life course on gene expression. The role of differential social and environmental exposures in racial disparities in BC suggests varied epigenetic profiles or signatures associated with specific BC subtypes in AA and EA women. These epigenetic profiles in EA and AA women could be used as biomarkers for early BC diagnosis and disease prognosis and may prove valuable for the development of targeted therapies for BC. This review article discusses the current state of knowledge regarding epigenetic differences between AA and EA women with BC. We also discuss the role of socio-environmental factors, including psychosocial stress, environmental toxicants, and dietary factors, in delineating the different epigenetic profiles in AA and EA patients with BC.

Evaluating the challenges and reproducibility of studies investigating DNA methylation signatures of psychological stress

Psychological stress can increase the risk of a wide range of negative health outcomes. Studies have been completed to determine if DNA methylation changes occur in the human brain because of stress and are associated with long-term effects and disease, but results have been inconsistent. Human candidate gene studies (150) and epigenome-wide association studies (67) were systematically evaluated to assess how DNA methylation is impacted by stress during the prenatal period, early childhood and adulthood. The association between DNA methylation of NR3C1 exon 1F and child maltreatment and early life adversity was well demonstrated, but other genes did not exhibit a clear association. The reproducibility of individual CpG sites in epigenome-wide association studies was also poor. However, biological pathways, including stress response, brain development and immunity, have been consistently identified across different stressors throughout the life span. Future studies would benefit from the increased sample size, longitudinal design, standardized methodology, optimal quality control, and improved statistical procedures.

An Epigenetic Perspective on Lifestyle Medicine for Depression: Implications for Primary Care Practice

Depression is the most common presenting mental health disorder in primary care. It is also a major contributor to somatic complaints, worsening of chronic medical conditions, poor quality of life, and suicide. Current pharmacologic and psychotherapeutic approaches avert less than half of depression's cumulative burden on society. However, there is a growing body of research describing both how maladaptive lifestyle choices contribute to the development and worsening of depression and how lifestyle-oriented medical interventions can reduce the incidence and severity of depression. This research, largely derived from an emerging field called epigenetics, elucidates the interactions between our lifestyle choices and those epigenetic factors which mediate our tendencies toward either health, or the onset, if not worsening of disease. The present review highlights how lifestyle choices involving diet, physical activity, sleep, social relationships, and stress influence epigenetic processes positively or negatively, and thereby play a significant role in determining whether one does or does not suffer from depression. The authors propose that medical training programs consider and adopt lifestyle medicine oriented instructional initiatives that will enable tomorrow's primary care providers to more effectively identify and therapeutically intervene in the maladaptive choices contributing to their patients' depression.

DNA methylation of the glucocorticoid receptor gene predicts substance use in adolescence: longitudinal data from over 1000 young individuals

Early life stress has been linked to increased methylation of the Nuclear Receptor Subfamily 3 Group C Member 1 (NR3C1) gene, which codes for the glucocorticoid receptor. Moreover, early life stress has been associated with substance use initiation at a younger age, a risk factor for developing substance use disorders. However, no studies to date have investigated whether NR3C1 methylation can predict substance use in young individuals. This study included adolescents 13-14 years of age that reported no history of substance use at baseline, (N = 1041; males = 46%). Participants contributed saliva DNA samples and were followed in middle adolescence as part of KUPOL, a prospective cohort study of 7th-grade students in Sweden. Outcome variables were self-reports of (i) recent use, (ii) lifetime use, and (iii) use duration of (a) alcohol, (b) tobacco products, (c) cannabis, or (d) any substance. Outcomes were measured annually for three consecutive years. The predictor variable was DNA methylation at the exon 1 F locus of NR3C1. Risk and rate ratios were calculated as measures of association, with or without adjustment for internalizing symptoms and parental psychiatric disorders. For a subset of individuals (N = 320), there were also morning and afternoon salivary cortisol measurements available that were analyzed in relation to NR3C1 methylation levels. Baseline NR3C1 hypermethylation associated with future self-reports of recent use and use duration of any substance, before and after adjustment for potential confounders. The overall estimates were attenuated when considering lifetime use. Sex-stratified analyses revealed the strongest association for cigarette use in males. Cortisol analyses revealed associations between NR3C1 methylation and morning cortisol levels. Findings from this study suggest that saliva NR3C1 hypermethylation can predict substance use in middle adolescence. Additional longitudinal studies are warranted to confirm these findings.

DNA methylation signature as a biomarker of major neuropsychiatric disorders

DNA methylation is a broadly-investigated epigenetic modification that has been considered as a heritable and reversible change. Previous findings have indicated that DNA methylation regulates gene expression in the central nervous system (CNS). Also, disturbance of DNA methylation patterns has been associated with destructive consequences that lead to human brain diseases such as neuropsychiatric disorders (NPDs). In this review, we comprehensively discuss the mechanism and function of DNA methylation and its most recent associations with the pathology of NPDs-including major depressive disorder (MDD), schizophrenia (SZ), autism spectrum disorder (ASD), bipolar disorder (BD), and attention/deficit hyperactivity disorder (ADHD). We also discuss how heterogeneous findings demand further investigations. Finally, based on the recent studies we conclude that DNA methylation status may have implications in clinical diagnostics and therapeutics as a potential epigenetic biomarker of NPDs.

Gut Hormones as Potential Therapeutic Targets or Biomarkers of Response in Depression: The Case of Motilin

Recent research has identified the gut–brain axis as a key mechanistic pathway and potential therapeutic target in depression. In this paper, the potential role of gut hormones as potential treatments or predictors of response in depression is examined, with specific reference to the peptide hormone motilin. This possibility is explored through two methods: (1) a conceptual review of the possible links between motilin and depression, including evidence from animal and human research as well as clinical trials, based on a literature search of three scientific databases, and (2) an analysis of the relationship between a functional polymorphism (rs2281820) of the motilin (MLN) gene and cross-national variations in the prevalence of depression based on allele frequency data after correction for potential confounders. It was observed that (1) there are several plausible mechanisms, including interactions with diet, monoamine, and neuroendocrine pathways, to suggest that motilin may be relevant to the pathophysiology and treatment of depression, and (2) there was a significant correlation between rs2281820 allele frequencies and the prevalence of depression after correcting for multiple confounding factors. These results suggest that further evaluation of the utility of motilin and related gut peptides as markers of antidepressant response is required and that these molecular pathways represent potential future mechanisms for antidepressant drug development.

Associations of age, sex, sexual abuse, and genotype with monoamine oxidase a gene methylation

Epigenome-wide studies report higher methylation among women than men with decreasing levels with age. Little is known about associations of sex and age with methylation of monoamine oxidase A (MAOA). Methylation of the first exonic and partial first intronic region of MAOA has been shown to strengthen associations of interactions of MAOA-uVNTR genotypes and adversity with aggression and substance misuse. Our study examined associations of sex and age with MAOA first exon and intron methylation levels in 252 women and 157 men aged 14–73 years. Participants included adolescents recruited at a substance misuse clinic, their siblings and parents, and healthy women. Women showed ~ 50% higher levels of exonic, and ~ 15% higher intronic, methylation than men. Methylation levels were similar between younger (M = 22.7 years) and older (M = 46.1 years) participants, and stable across age. Age modified few associations of methylation levels with sex. MAOA genotypes modified few associations of methylation with sex and age. Higher methylation levels among women were not explained by genotype, nor interaction of genotype and sexual abuse. Findings were similar after adjusting for lifetime diagnoses of substance dependence (women = 24.3%; men = 34.2%). Methylation levels were higher among women who experienced sexual abuse than women who did not. Results extend on prior studies by showing that women display higher levels of methylation than men within first intronic/exonic regions of MAOA, which did not decrease with age in either sex. Findings were not conditioned by genotype nor interactions of genotype and trauma, and indicate X-chromosome inactivation.

Childhood trauma, the stress response and metabolic syndrome: A focus on DNA methylation

Childhood trauma (CT) is well established as a potent risk factor for the development of mental disorders. However, the potential of adverse early experiences to exert chronic and profound effects on physical health, including aberrant metabolic phenotypes, has only been more recently explored. Among these consequences is metabolic syndrome (MetS), which is characterised by at least three of five related cardiometabolic traits: hypertension, insulin resistance/hyperglycaemia, raised triglycerides, low high-density lipoprotein and central obesity. The deleterious effects of CT on health outcomes may be partially attributable to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which coordinates the response to stress, and the consequent fostering of a pro-inflammatory environment. Epigenetic tags, such as DNA methylation, which are sensitive to environmental influences provide a means whereby the effects of CT can be biologically embedded and persist into adulthood to affect health and well-being. The methylome regulates the transcription of genes involved in the stress response, metabolism and inflammation. This narrative review examines the evidence for DNA methylation in CT and MetS in order to identify shared neuroendocrine and immune correlates that may mediate the increased risk of MetS following CT exposure. Our review specifically highlights differential methylation of FKBP5, the gene that encodes FK506-binding protein 51 and has pleiotropic effects on stress responding, inflammation and energy metabolism, as a central candidate to understand the molecular aetiology underlying CT-associated MetS risk.

Social epigenomics: are we at an impasse?

Aim: Social scientists have placed particularly high expectations on the study of epigenomics to explain how exposure to adverse social factors like poverty, child maltreatment and racism - particularly early in childhood - might contribute to complex diseases. However, progress has stalled, reflecting many of the same challenges faced in genomics, including overhype, lack of diversity in samples, limited replication and difficulty interpreting significance of findings. Materials & methods: This review focuses on the future of social epigenomics by discussing progress made, ongoing methodological and analytical challenges and suggestions for improvement. Results & conclusion: Recommendations include more diverse sample types, cross-cultural, longitudinal and multi-generational studies. True integration of social and epigenomic data will require increased access to both data types in publicly available databases, enhanced data integration frameworks, and more collaborative efforts between social scientists and geneticists.

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.

Genetic and Epigenetic Consequence of Early-Life Social Stress on Depression: Role of Serotonin-Associated Genes

Early-life adversity caused by poor social bonding and deprived maternal care is known to affect mental wellbeing and physical health. It is a form of chronic social stress that persists because of a negative environment, and the consequences are long-lasting on mental health. The presence of social stress during early life can have an epigenetic effect on the body, possibly resulting in many complex mental disorders, including depression in later life. Here, we review the evidence for early-life social stress-induced epigenetic changes that modulate juvenile and adult social behavior (depression and anxiety). This review has a particular emphasis on the interaction between early-life social stress and genetic variation of serotonin associate genes including the serotonin transporter gene (5-HTT; also known as SLC6A4), which are key molecules involved in depression.

mRNA Levels of MAOA and 5-HT 2 A Receptor in Patients With Pathological Internet Use: Correlations With Comorbid Symptoms

Objective: Uncontrolled internet use may lead to the emergence of pathological internet use (PIU). PIU has become a global public health concern that can cause a range of psychotic symptoms, including anxiety, depression, and impulse control disorder. To date, we know very little about the principal biological factors related to PIU. Monoamine oxidase type A (MAOA) and serotonin (5-HT) 5-HT_2A receptor (5-HT_2AR) play critical roles in the development of behavioural and drug addictions. Thus, the aim of this study was to measure the relative expression of mRNA of MAOA and 5-HT_2AR in peripheral blood mononuclear cells (PBMCs) of patients with PIU and to determine the correlations between these biological indicators and the comorbid symptoms of patients with PIU. Methods: In this study, the mRNA of MAOA and 5-HT_2AR was detected using real-time PCR in PBMCs of the patients with PIU (n = 24) and healthy controls (HCs, n = 25). The relationship between the mRNA levels of MAOA and 5-HT_2AR and clinical symptoms in patients with PIU was further investigated. Results: MAOA mRNA in PBMCs was significantly upregulated in patients with PIU compared with that in HCs. mRNA levels of 5-HT_2AR were not found to differ significantly between HCs and patients with PIU. Correlation analyses further revealed a significant positive correlation between the relative expression of MAOA mRNA in PBMCs of patients with PIU and the Young's Internet Addiction Test and Self-Rating Depression Scale scores. Conclusion: The present study revealed upregulated expression of MAOA mRNA in patients with PIU and an association between the expression of MAOA mRNA and clinical symptoms of PIU, suggesting that the neurobiological changes may be similar between PIU and substance addiction. Additionally, this study demonstrated a potential association between comorbid symptoms and mRNA levels of MAOA.

Childhood adversity increases methylation in the GRIN2B gene

Childhood adversity is an early life stressor associated with increased risk of several psychiatric disorders such as depression. Epigenetic changes, primarily DNA methylation, can be affected by early life stress, which in turn might contribute to altered disease susceptibility later in life. One plausible biomarker of early life stress is methylation of the ionotropic glutamate receptor NMDA type subunit 2B (GRIN2B) gene, which has been previously shown to be epigenetically affected by prenatal environmental stressors. Here, we set out to investigate if stress-inducing adversity during childhood is associated with changes in methylation of GRIN2B in adulthood. We studied 186 individuals from a Swedish naturalistic population-based cohort who had provided saliva samples (DNA) as well as information regarding both childhood adversity (CA) and depressive symptoms (dep) (n_CA,dep = 41, n_CA,no-dep = 56, n_no-CA,dep = 40, N_no-CA,no-dep = 49). Methylation at four CpG sites in a regulatory region of GRIN2B was analysed using bisulfite pyrosequencing. Associations for methylation status to childhood adversity and to depression status were investigated using linear regression models. Our study shows that childhood adversity is associated with increased methylation levels of GRIN2B in adulthood, for three of the measured CpGs (p = 0.007, 0.006 and 5 × 10^-14). This indicates that GRIN2B methylation is susceptible to early life stress, and that methylation at this gene is persistent over time. No association was found between GRIN2B methylation and depression status. Yet, this does not rule out a role for alterations in GRIN2B methylation for other neuropsychological outcomes not studied here.

Monoamino Oxidase A Gene Single-Nucleotide Polymorphisms and Methylation Status and the Risk of Violent Suicide Attempts in Affective Disorder Patients

Background: When investigating the neurobiology of suicidal behavior, Monoamino Oxidase A (MAOA) is one of the prime suspects to consider. Interestingly, MAOA dysregulation has also been associated with violent behavior in previous publications. In the present study, we aimed to establish an association between polymorphisms of the MAOA gene and methylation status of the MAOA gene Exon I, and suicide attempts with violent methods in a sample of affective disorder patients. Methods: Eight hundred fourteen Caucasian affective disorder patients were assessed at the Department of Psychiatry and Psychotherapy of the Medical University Vienna, the Karl Landsteiner University for Health and Science and Zentren für seelische Gesundheit, BBRZ-Med Leopoldau. An assemblage of psychiatric interviews was performed (e.g., SCAN, HAMD, SBQ-R, CTQ) and DNA samples of peripheral blood cells were collected for Sequenom MassARRAY® iPLEX Gold genotyping and Multiplexed and Sensitive DNA Methylation Testing. Results: Female affective disorder patients with a history of violent suicide attempt were found to have a significantly increased frequency of the AA genotype in the rs5906957 single nucleotide polymorphism (p = 0.003). Furthermore, the MAOA gene exon I promoter region showed significantly decreased methylation in female violent suicide attempter(s) as opposed to female affective disorder patients who had no history of suicide attempt or no history of suicide attempt with violent method. Limitations: The small sample size hampers to reveal small genetic effects as to be expected in psychiatric disorders. Conclusions: This study offers promising findings about associations between the MAOA gene and violent suicide especially in women.

Glucocorticoid receptor signaling in leukocytes after early life adversity

Early life adversity (ELA) has been associated with inflammation and immunosenescence, as well as hyporeactivity of the HPA axis. Because the immune system and the HPA axis are tightly intertwined around the glucocorticoid receptor (GR), we examined peripheral GR functionality in the EpiPath cohort among participants who either had been exposed to ELA (separation from parents and/or institutionalization followed by adoption; n = 40) or had been reared by their biological parents (n = 72).Expression of the strict GR target genes FKBP5 and GILZ as well as total and 1F and 1H GR transcripts were similar between groups. Furthermore, there were no differences in GR sensitivity, examined by the effects of dexamethasone on IL6 production in LPS-stimulated whole blood. Although we did not find differences in methylation at the GR 1F exon or promoter region, we identified a region of the GR 1H promoter (CpG 1-9) that showed lower methylation levels in ELA.Our results suggest that peripheral GR signaling was unperturbed in our cohort and the observed immune phenotype does not appear to be secondary to an altered GR response to the perturbed HPA axis and glucocorticoid (GC) profile, although we are limited in our measures of GR activity and time points.

Lifetime stress and war exposure timing may predict methylation changes at NR3C1 based on a pilot study in a warrior cohort in a small-scale society in Kenya

OBJECTIVES

Candidate gene methylation studies of NR3C1 have identified associations with psychosocial adversity, including war trauma. This pilot study (sample sizes from 22 to 45 for primary analyses) examined NR3C1 methylation in a group of Kenyan pastoralist young men in relation to culturally relevant traumatic experiences, including participation in coalitional lethal gun violence.

METHODS

Adolescent and young adult Samburu men ("warriors") were recruited for participation. DNA was obtained from whole saliva and methylation analyses performed using mass spectrometry. We performed a data reduction of variables from a standardized instrument of lifetime stress using a factor analysis and we assessed the association between the extracted factors with culturally relevant and cross-culturally comparative experiences.

RESULTS

Cumulative lifetime trauma exposure and forms of violence to which warriors are particularly susceptible were associated with DNA methylation changes in the NR3C1 1_F promoter region but not in the NR3C1 1_D promoter region. However, sensitivity analyses revealed significant associations between individual CpG sites in both regions and cumulative stress exposures, war exposure timing, and war fatalities.

CONCLUSIONS

This study supports the importance of NR3C1 methylation changes in response to challenging life circumstances, including in a global south cultural context that contrasts in notable ways from global north contexts and from the starkly tragic examples of the Rwandan genocide and war-associated rape explored in recent studies. Timing of traumatic exposure and culturally salient means to measure enduring symptoms of trauma remain important considerations for DNA methylation studies.

Effect of Early Life Stress on the Epigenetic Profiles in Depression

Depression is one of the most common mental disorders and has caused an overwhelming burden on world health. Abundant studies have suggested that early life stress may grant depressive-like phenotypes in adults. Childhood adversities that occurred in the developmental period amplified stress events in adulthood. Epigenetic-environment interaction helps to explain the role of early life stress on adulthood depression. Early life stress shaped the epigenetic profiles of the HPA axis, monoamine, and neuropeptides. In the context of early adversities increasing the risk of depression, early life stress decreased the activity of the glucocorticoid receptors, halted the circulation and production of serotonin, and reduced the molecules involved in modulating the neurogenesis and neuroplasticity. Generally, DNA methylation, histone modifications, and the regulation of non-coding RNAs programmed the epigenetic profiles to react to early life stress. However, genetic precondition, subtypes of early life stress, the timing of epigenetic status evaluated, demographic characteristics in humans, and strain traits in animals favored epigenetic outcomes. More research is needed to investigate the direct evidence for how early life stress-induced epigenetic changes contribute to the vulnerability of depression.

Epigenetic landscape of stress surfeit disorders: Key role for DNA methylation dynamics

Chronic exposure to stress throughout lifespan alters brain structure and function, inducing a maladaptive response to environmental stimuli, that can contribute to the development of a pathological phenotype. Studies have shown that hypothalamic-pituitary-adrenal (HPA) axis dysfunction is associated with various neuropsychiatric disorders, including major depressive, alcohol use and post-traumatic stress disorders. Downstream actors of the HPA axis, glucocorticoids are critical mediators of the stress response and exert their function through specific receptors, i.e., the glucocorticoid receptor (GR), highly expressed in stress/reward-integrative pathways. GRs are ligand-activated transcription factors that recruit epigenetic actors to regulate gene expression via DNA methylation, altering chromatin structure and thus shaping the response to stress. The dynamic interplay between stress response and epigenetic modifiers suggest DNA methylation plays a key role in the development of stress surfeit disorders.

The link between parental psychological control, depressive symptoms and epigenetic changes in the glucocorticoid receptor gene (NR3C1)

AIMS

This paper examines the relationship between parental Psychological Control (PC) and depressive symptoms in adolescents and assesses whether this relationship was mediated by DNA methylation, focusing on the glucocorticoid receptor gene (NR3C1), which plays a crucial role in HPA-axis functioning and is linked to environmental stress and depression. This is among the very few studies that looked at the relation between DNA methylation, environmental stress and depression in family trios.

METHODS

The study cohort consisted of 250 families: father, mother and a biologically related adolescent (adolescents (48.9% boys), mean age: 15.14, SD= 1.9; mean age mothers: 45.83, SD= 4.2; mean age fathers: 47.77, SD= 4.7). Depressive symptoms and PC were measured in adolescents and in both parents. DNA methylation levels in NR3C1 were examined in all participants.

RESULTS

Depressive symptoms in adolescents were predicted by PC of both mothers and fathers. Moreover, maternal depressive symptoms were associated with maternal PC, and fathers' depressive symptoms and PC. In fathers, only the level of their self-reported PC was associated with their depressive symptoms. There was no relation between adolescents' DNA methylation and depressive symptoms or the level of parental PC. Yet, there was a significant association between maternal depressive symptoms and maternal epigenetic patterns in NR3C1.

CONCLUSIONS

These findings highlight the need for more research in order to better understand the biological and contextual mechanisms through which parenting and parental emotional well-being is related to the development of psychopathology.

Early Life Stress Induced DNA Methylation of Monoamine Oxidases Leads to Depressive-Like Behavior

Major depressive disorder (MDD) is coming to be the regarded as one of the leading causes for human disabilities. Due to its complicated pathological process, the etiology is still unclear and the treatment is still targeting at the monoamine neurotransmitters. Early life stress has been known as a major cause for MDD, but how early life stress affects adult monoaminergic activity is not clear either. Recently, DNA methylation is considered to be the key mechanism of epigenetics and might play a role in early life stress induced mental illness. DNA methylation is an enzymatic covalent modification of DNA, has been one of the main epigenetic mechanisms investigated. The metabolic enzyme for the monoamine neurotransmitters, monoamine oxidases A/B (MAO A/MAO B) are the prime candidates for the investigation into the role of DNA methylation in mental disorders. In this review, we will review recent advances about the structure and physiological function of monoamine oxidases (MAO), brief narrative other factors include stress induced changes, early life stress, perinatal depression (PD) relationship with other epigenetic changes, such as DNA methylation, microRNA (miRNA). This review will shed light on the epigenetic changes involved in MDD, which may provide potential targets for future therapeutics in depression pathogenesis.

Epigenetic alterations associated with childhood trauma and adult mental health outcomes: A systematic review

Objectives: Multiple, chronic and repeated trauma exposure in childhood is associated with adverse mental health outcomes in adulthood. In this paper we synthesise the literature on epigenetic modifications in childhood trauma (CT) and the mediating effects of differential epigenetic mechanisms on the association between CT and the later onset of psychiatric disorders.Methods: We reviewed the literature up to March 2018 in four databases: PubMed, Web of Science, EBSCOhost and SCOPUS. Non-human studies were excluded. All studies investigating CT exposure both in healthy adults (18 years and older) and adults with psychiatric disorders were included.Results: Thirty-six publications were included. For mood disorders, methylation of the glucocorticoid receptor NR3C1 gene, specifically at the NGFI-A binding site in exon 1F, and correlation with CT was a robust finding. Several studies documented differential methylation of SLC6A4, BDNF, OXTR and FKBP5 in association with CT. Common pathways identified include neuronal functioning and maintenance, immune and inflammatory processes, chromatin and histone modification, and transcription factor binding.Conclusions: A variety of epigenetic mediators that lie on a common pathway between CT and psychiatric disorders have been identified, although longitudinal studies and consistency in methodological approach are needed to disentangle cause and effect associations.

Psychological Stress, Intestinal Barrier Dysfunctions, and Autoimmune Disorders: An Overview

Autoimmune disorders (ADs) are multifactorial diseases involving, genetic, epigenetic, and environmental factors characterized by an inappropriate immune response toward self-antigens. In the past decades, there has been a continuous rise in the incidence of ADs, which cannot be explained by genetic factors alone. Influence of psychological stress on the development or the course of autoimmune disorders has been discussed for a long time. Indeed, based on epidemiological studies, stress has been suggested to precede AD occurrence and to exacerbate symptoms. Furthermore, compiling data showed that most of ADs are associated with gastrointestinal symptoms, that is, microbiota dysbiosis, intestinal hyperpermeability, and intestinal inflammation. Interestingly, social stress (acute or chronic, in adult or in neonate) is a well-described intestinal disrupting factor. Taken together, those observations question a potential role of stress-induced defect of the intestinal barrier in the onset and/or the course of ADs. In this review, we aim to present evidences supporting the hypothesis for a role of stress-induced intestinal barrier disruption in the onset and/or the course of ADs. We will mainly focus on autoimmune type 1 diabetes, multiple sclerosis and systemic lupus erythematosus, ADs for which we could find sufficient circumstantial data to support this hypothesis. We excluded gastrointestinal (GI) ADs like coeliac disease to privilege ADs not focused on intestinal disorders to avoid confounding factors. Indeed, GIADs are characterized by antibodies directed against intestinal barrier actors.

Scars of childhood socioeconomic stress: A systematic review

Childhood socioeconomic position (SEP) is associated with the development of adult psychological outcomes, with DNA methylation (DNAm) as a mechanism to potentially explain these changes. We present the first systematic review synthesising the literature investigating childhood SEP and DNAm. Thirty-two publications were included. Seventeen studies focused on candidate genes, typically focusing on genes implicated with the stress response and/or development of psychiatric conditions. These studies typically investigated different regions of the genes, which revealed inconsistent results. Six studies calculated epigenetic age, with a small number revealing an elevated significant association with childhood SEP. Epigenome-wide studies revealed altered patterns of DNAm which varied between the nine studies. This research area is emerging and demonstrated great variance in findings with no clear patterns identified across studies. Multiple methodological shortcomings are identified, including at the phenotypic level where construct validity of childhood SEP is highly inconsistent, with studies using a wide range of measures. Larger cohorts will be required with international collaborations to strengthen this research area.

Epigenetic mechanisms activated by childhood adversity

Adverse childhood experiences (ACE) impair health and life expectancy and may result in an epigenetic signature that drives increased morbidity primed during early stages of life. This literature review focuses on the current evidence for epigenetic-mediated programming of brain and immune function resulting from ACE. To address this aim, a total of 88 articles indexed in PubMed before August 2019 concerning ACE and epigenetics were surveyed. Current evidence partially supports epigenetic programming of the hypothalamic-pituitary-adrenal axis, but convincingly shows that ACE impairs immune function. Additionally, the needs and challenges that face this area are discussed in order to provide a framework that may help to clarify the role of epigenetics in the long-lasting effects of ACE.

DNA hypomethylation of the Krüppel-like factor 11 (KLF11) gene promoter: a putative biomarker of depression comorbidity in panic disorder and of non-anxious depression?

Panic disorder (PD) is one of the most common anxiety disorders and often occurs comorbidly with major depressive disorder (MDD). Altered methylation of the monoamine oxidase A (MAOA) gene has been implicated in the etiology of both PD and MDD. The Krüppel-like factor 11 (KLF11; alias TIEG2), an activating transcription factor of the MAOA gene, has been found to be increased in MDD, but has not yet been investigated in PD. In an effort to further delineate the effects of the KLF11–MAOA pathway in anxiety and affective disorders, KLF11 promoter methylation was analyzed via pyrosequencing of sodium bisulfite-treated DNA isolated from human peripheral blood in two independent samples of PD patients with or without comorbid MDD in a case–control design (sample 1: N = 120) as well as MDD patients with and without anxious depression (sample 2: N = 170). Additionally, in sample 1, KLF11 methylation was correlated with Beck Depression Inventory (BDI-II) scores. No overall association of KLF11 promoter methylation with PD was detected. However, PD patients with comorbid MDD showed significant hypomethylation relative to both healthy controls (p = 0.010) and PD patients without comorbid MDD (p = 0.008). Furthermore, KLF11 methylation was negatively correlated with BDI-II scores in PD patients (p = 0.013). MDD patients without anxious features showed nominally decreased KLF11 methylation in comparison to MDD patients with anxious depression (p = 0.052). The present results suggest KLF11 promoter hypomethylation as a potential epigenetic marker of MDD comorbidity in PD or of non-anxious depression, respectively, possibly constituting a differential pathomechanism in anxiety and mood disorders.