Maternal psychosocial stress during pregnancy alters the epigenetic signature of the glucocorticoid receptor gene promoter in their offspring: a meta-analysis

Does maternal mental well-being in pregnancy impact the early human epigenome?

There is considerable interest in the potential nongenetic transmission of a suite of mental health conditions across generations, with epigenetics emerging as a candidate mediator of such effects. This review summarizes findings from 22 studies measuring candidate gene DNA methylation and seven epigenome-wide association studies of offspring epigenetic profile in women with adverse mental wellbeing measures (stress, depression or anxiety) in pregnancy. Despite some compelling evidence to suggest an association, there is a lack of reproducible findings, potentially linked to a number of limitations to this research and the field more broadly. Large cohorts with well characterized exposures across pregnancy are now needed. There is exciting potential that epigenetics may help explain some of the link between maternal wellbeing and child health outcomes, thereby informing novel interventions, but future studies must address current limitations to advance translational knowledge in this area.

Maternal Depressive Symptoms During and After Pregnancy and Psychiatric Problems in Children

OBJECTIVE

Maternal depressive symptoms during pregnancy are associated with increased risk of psychiatric problems in children. A more precise understanding of the timing of the symptoms during pregnancy and their independence of other prenatal and postnatal factors in predicting child psychopathology risk is needed. We examined whether maternal depressive symptoms during pregnancy predict child psychiatric problems, whether these associations are trimester- or gestational-week-specific and/or independent of pregnancy disorders, and whether maternal depressive symptoms after pregnancy mediate or add to the prenatal effects.

METHOD

The study sample comprised 2,296 women and their children born in Finland between 2006-2010, participating in the prospective pregnancy cohort study Prediction and Prevention of Preeclampsia and Intrauterine Growth Restriction (PREDO) and followed up from 1.9 to 5.9 years of age. The women completed the Center for Epidemiologic Studies Depression Scale biweekly between gestational weeks+days 12+0/13+6 and 38+0/39+6 or delivery. In the follow-up, they completed the Beck Depression Inventory-II and Child Behavior Checklist 1½-5.

RESULTS

Maternal depressive symptoms during pregnancy predicted significantly higher internalizing (0.28 SD unit per SD unit increase [95% CI = 0.24-0.32]), externalizing (0.26 [0.23-0.30]), and total problems (0.31 [0.27-0.35]) in children. These associations were nonspecific to gestational week and hence pregnancy trimester, independent of pregnancy disorders, and independent of, although partially mediated by, maternal depressive symptoms after pregnancy. Psychiatric problems were greatest in children whose mothers reported clinically significant depressive symptoms across pregnancy trimesters and during and after pregnancy.

CONCLUSION

Maternal depressive symptoms during pregnancy predict increased psychiatric problems in young children. Preventive interventions from early pregnancy onward may benefit offspring mental health.

Long-Term Effects of the Periconception Period on Embryo Epigenetic Profile and Phenotype: The Role of Stress and How This Effect Is Mediated

Stress represents an unavoidable aspect of human life, and pathologies associated with dysregulation of stress mechanisms - particularly psychiatric disorders - represent a significant global health problem. While it has long been observed that levels of stress experienced in the periconception period may greatly affect the offspring's risk of psychiatric disorders, the mechanisms underlying these associations are not yet comprehensively understood. In order to address this question, this chapter will take a 'top-down' approach, by first defining stress and associated concepts, before exploring the mechanistic basis of the stress response in the form of the hypothalamic-pituitary-adrenal (HPA) axis, and how dysregulation of the HPA axis can impede our mental and physical health, primarily via imbalances in glucocorticoids (GCs) and their corresponding receptors (GRs) in the brain. The current extent of knowledge pertaining to the impact of stress on developmental programming and epigenetic inheritance is then extensively discussed, including the role of chromatin remodelling associated with specific HPA axis-related genes and the possible role of regulatory RNAs as messengers of environmental stress both in the intrauterine environment and across the germ line. Furthering our understanding of the role of stress on embryonic development is crucial if we are to increase our predictive power of disease risk and devise-effective treatments and intervention strategies.

DNA Methylation in Major Depressive Disorder

Epigenetic mechanisms regulate gene expression, influencing protein levels and ultimately shaping phenotypes during life. However, both stochastic epigenetic variations and environmental reprogramming of the epigenome might influence neurodevelopment and ageing, and this may contribute to the origins of mental ill-health. Studying the role of epigenetic mechanisms is challenging, as genotype-, tissue- and cell type-dependent epigenetic changes have to be taken into account, while the nature of mental disorders also poses significant challenges for linking them with biological profiles. In this chapter, we summarise the current evidence suggesting the role of DNA methylation as a key epigenetic mechanism in major depressive disorder.

Prenatal anxiety, maternal stroking in infancy, and symptoms of emotional and behavioral disorders at 3.5 years

Animal findings of long-term effects of maternal behaviors mediated via altered GR gene expression will, if translated into humans, have far reaching implications for our understanding of child and adolescent psychopathology. We have previously shown that mothers' self-reported stroking of their infants modifies associations between prenatal depression and anxiety and child outcomes at 29 weeks and 2.5 years. Here, we examine whether the effect of early maternal stroking is evident at 3.5 years, and in a much larger sample than in previous publications. A general population sample of 1233 first-time mothers completed anxiety measures at 20 weeks gestation, 865 reported on infant stroking at 9 weeks, and 813 on child symptoms at 3.5 years. Maternal stroking moderated the association between pregnancy-specific anxiety and internalizing (p = 0.010) and externalizing (p = 0.004) scores, such that an effect of PSA to increase symptoms was markedly reduced for mothers who reported high levels of stroking. There was no effect of maternal stroking on general anxiety. The findings confirm the previously reported effect of maternal stroking, and in a much larger sample. They indicate that there are long-term effects of early maternal stroking, modifying associations between prenatal anxiety and child emotional and behavioral symptoms.

History of violence and subjective health of mother and child

OBJECTIVE

To study the self-reported prevalence of experienced violence among a cohort of women about two years after giving birth, their health during pregnancy, pregnancy outcomes and their experience of their child's health.

SETTING AND SUBJECTS

In 2011, a total of 657 women participated in phase III of the Childbirth and Health Cohort Study in Icelandic Primary Health Care, 18 to 24 months after delivery. The women had previously participated in phase I around pregnancy week 16 and phase II 5-6 months after delivery. Data were collected by postal questionnaires.

MAIN OUTCOME MEASURES

Women's reported history of experienced violence, sociodemographic and obstetric background, self-perceived health, the use of medications and their child's perceived health.

RESULTS

In phase III, 16% of women reported experiencing violence. These women felt less support from their current partner (p < 0.001), compared to those who did not report violence. Their pregnancies were more frequently unplanned (p < 0.001), deliveries more often by caesarean section (p < 0.05), and their self-perceived health was worse (p < 0.001). They reported more mental and somatic health complaints, and their use of antidepressant drugs was higher (p < 0.001). Furthermore, women with a history of violence considered their child's general health as worse (p = 0.008).

CONCLUSIONS

Our study confirms that a history of violence is common among women. A history of violence is associated with various maternal health problems during and after pregnancy, a higher rate of caesarean sections and maternal reports of health problems in their child 18-24 months after birth. KEY POINTS   Violence is a major concern worldwide. Understanding the impact of violence on human health and developing effective preventive measures are important elements of any public health agenda.   • The reported prevalence of experiencing violence was 16% among women attending antenatal care in the primary health care setting in Iceland.   • Women with a history of violence reported worse health in general during pregnancy and delivered more often by caesarean section, compared to women with no such history.   • Mothers with a history of violence also evaluated the general health of their child as worse than women with no such history.   • The findings of this study support the importance of recognizing and addressing experienced violence among women in primary care.

Glucocorticoid receptor DNA methylation, childhood maltreatment and major depression

INTRODUCTION

Altered DNA methylation (DNAm) levels of hypothalamic-pituitary-adrenal (HPA) axis genes has been associated with exposure to childhood maltreatment (CM) and depression; however, it is unknown whether CM and depression have joint and potentially interacting effects on the glucocorticoid receptor (NR3C1) DNAm. We investigated the impact of CM and lifetime major depressive disorder (MDD) on NR3C1 DNAm and gene expression (GE) in 147 adult participants from the Detroit Neighborhood Health Study.

METHODS

NR3C1 promoter region DNAm was assessed via pyrosequencing using whole blood-derived DNA. Quantitative RT-PCR assays measured GE from leukocyte-derived RNA. Linear regression models were used to examine the relationship among CM, MDD, and DNAm.

RESULTS

Both CM and MDD were significant predictors of NR3C1 DNAm: CM was associated with an increase in DNAm in an EGR1 transcription factor binding site (TFBS), whereas MDD was associated with a decrease in DNAm downstream of the TFBS. No significant CM-MDD interactions were observed. CM alone was associated with significantly lower NR3C1 GE.

LIMITATIONS

Our report of CM is a retrospective self-report of abuse, which may introduce recall bias. DNAm was measured in whole blood and may not reflect brain-derived DNAm levels.

CONCLUSIONS

CM and MDD are both associated with altered DNAm levels in the NR3C1 promoter region, however the location and direction of effects differ between the two exposures, and the functional effects, as measured by GE, appear to be limited to CM exposure alone. CM exposure may be biologically embedded in this key HPA axis gene.

Biological underpinnings of trauma and post-traumatic stress disorder: focusing on genetics and epigenetics

Certain individuals are more susceptible to stress and trauma, as well as the physical and mental health consequences following such exposure, including risk for post-traumatic stress disorder (PTSD). This differing vulnerability is likely to be influenced by genetic predisposition and specific characteristics of the stress itself (nature, intensity and duration), as well as epigenetic mechanisms. In this review we provide an overview of research findings in this field. We highlight some of the key genetic risk factors identified for PTSD, and the evidence that epigenetic processes might play a role in the biological response to trauma, as well as being potential biomarkers of PTSD risk. We also discuss important considerations for future research in this area.

Epigenetic alterations induced by environmental stress associated with metabolic and neurodevelopmental disorders

Epigenetics is a gene regulation mechanism that does not depend on genomic DNA sequences but depends on chemical modification of genomic DNA and histone proteins around which DNA is wrapped. The failure of epigenetic mechanisms is known to cause various congenital disorders. It is also known that the failures of epigenetic mechanisms causes various acquired disorders since epigenetic modifications of the genome (i.e., "epigenome") are more vulnerable to environmental stress, such as malnutrition, environmental chemicals, and mental stress, than the "genome," especially during the early period of life. However, the epigenome has a reversible property since it is based on removable residues on genomic DNA. Thus, environmentally induced epigenomic alterations can be potentially restored. In fact, some medicines, especially for psychiatric diseases, are known to restore an altered epigenome, resulting in the correction of gene expression. Several lines of evidence suggest that environmentally induced epigenomic alterations are not erased completely during gametogenesis, but are transmitted to subsequent generations with disease phenotypes. In accordance with these understandings, I would like to propose the development of epigenomic-based preemptive medicine that consists of the early detection of the developmental origins of diseases using epigenomic signatures and the early intervention that take advantages of the use of epigenomic reversibility.

Adverse maternal exposures, methylation of glucocorticoid-related genes and perinatal outcomes: a systematic review

Aim: Maternal environmental exposures affect perinatal outcomes through epigenetic placental changes. We examine the literature addressing associations between adverse maternal exposures, perinatal outcomes and methylation of key genes regulating placental cortisol metabolism. Methods: We searched three databases for studies that examined NR3C1 and HSD11β1/HSD11 β 2 methylation with maternal exposures or perinatal outcomes. Nineteen studies remained after screening. We followed Cochrane's PRISMA reporting guidelines (2009). Results: NR3C1 and HSD11 β methylation were associated with adverse infant neurobehavior, stress response, blood pressure and physical development. In utero exposure to maternal stress, nutrition, preeclampsia, smoking and diabetes were associated with altered NR3C1 and HSD11 β methylation. Conclusion: NR3C1 and HSD11 β methylation are useful biomarkers of specific environmental stressors associated with important perinatal outcomes that determine pediatric and adult disease risk.

Epigenetic Effect of Environmental Factors on Autism Spectrum Disorders

Both environmental factors and genetic factors are involved in the pathogenesis of autism spectrum disorders (ASDs). Epigenetics, an essential mechanism for gene regulation based on chemical modifications of DNA and histone proteins, is also involved in congenital ASDs. It was recently demonstrated that environmental factors, such as endocrine disrupting chemicals and mental stress in early life, can change epigenetic status and gene expression, and can cause ASDs. Moreover, environmentally induced epigenetic changes are not erased during gametogenesis and are transmitted to subsequent generations, leading to changes in behavior phenotypes. However, epigenetics has a reversible nature since it is based on the addition or removal of chemical residues, and thus the original epigenetic status may be restored. Indeed, several antidepressants and anticonvulsants used for mental disorders including ASDs restore the epigenetic state and gene expression. Therefore, further epigenetic understanding of ASDs is important for the development of new drugs that take advantages of epigenetic reversibility.

The effects of maternal anxiety during pregnancy on IGF2/H19 methylation in cord blood

Compelling evidence suggests that maternal mental health in pregnancy can influence fetal development. The imprinted genes, insulin-like growth factor 2 (IGF2) and H19, are involved in fetal growth and each is regulated by DNA methylation. This study aimed to determine the association between maternal mental well-being during pregnancy and differentially methylated regions (DMRs) of IGF2 (DMR0) and the IGF2/H19 imprinting control region (ICR) in newborn offspring. Maternal depression, anxiety and perceived stress were assessed at 28 weeks of pregnancy in the Barwon Infant Study (n=576). DNA methylation was measured in purified cord blood mononuclear cells using the Sequenom MassArray Platform. Maternal anxiety was associated with a decrease in average ICR methylation (Δ=-2.23%; 95% CI=-3.68 to -0.77%), and across all six of the individual CpG units in anxious compared with non-anxious groups. Birth weight and sex modified the association between prenatal anxiety and infant methylation. When stratified into lower (⩽3530 g) and higher (>3530 g) birth weight groups using the median birth weight, there was a stronger association between anxiety and ICR methylation in the lower birth weight group (Δ=-3.89%; 95% CI=-6.06 to -1.72%), with no association in the higher birth weight group. When stratified by infant sex, there was a stronger association in female infants (Δ=-3.70%; 95% CI=-5.90 to -1.51%) and no association in males. All the linear regression models were adjusted for maternal age, smoking and folate intake. These findings show that maternal anxiety in pregnancy is associated with decreased IGF2/H19 ICR DNA methylation in progeny at birth, particularly in female, low birth weight neonates. ICR methylation may help link poor maternal mental health and adverse birth outcomes, but further investigation is needed.

Maternal Prenatal Positive Affect, Depressive and Anxiety Symptoms and Birth Outcomes: The PREDO Study

Background

We investigated whether maternal prenatal emotions are associated with gestational length and birth weight in the large PREDO Study with multiple measurement points of emotions during gestation.

Methods

Altogether 3376 pregnant women self-assessed their positive affect (PA, Positive and Negative Affect Schedule) and depressive (Center for Epidemiologic Studies Depression Scale, CES-D) and anxiety (Spielberger State Anxiety Scale, STAI) symptoms up to 14 times during gestation. Birth characteristics were derived from the National Birth Register and from medical records.

Results

One standard deviation (SD) unit higher PA during the third pregnancy trimester was associated with a 0.05 SD unit longer gestational length, whereas one SD unit higher CES-D and STAI scores during the third trimester were associated with 0.04–0.05 SD unit shorter gestational lengths (P-values ≤ 0.02), corresponding to only 0.1–0.2% of the variation in gestational length. Higher PA during the third trimester was associated with a significantly decreased risk for preterm (< 37 weeks) delivery (for each SD unit higher positive affect, odds ratio was 0.8-fold (P = 0.02). Mothers with preterm delivery showed a decline in PA and an increase in CES-D and STAI during eight weeks prior to delivery. Post-term birth (≥ 42 weeks), birth weight and fetal growth were not associated with maternal prenatal emotions.

Conclusions

This study with 14 measurements of maternal emotions during pregnancy show modest effects of prenatal emotions during the third pregnancy trimester, particularly in the weeks close to delivery, on gestational length. From the clinical perspective, the effects were negligible. No associations were detected between prenatal emotions and birth weight.