Childhood adversity and DNA methylation in two population-based cohorts

Associations of parental labour migration and childhood maltreatment with psychosocial health among adolescents and young adults in China

Background: Few studies have simultaneously considered the impacts of parental labour migration and childhood maltreatment on psychosocial health.Objective: To estimate the complex associations of parental labour migration and childhood maltreatment with psychosocial health among adolescents and young adults in China.Method: This cross-sectional study was conducted among undergraduates aged 17 to 24 years from sixty colleges and universities across 10 provinces of China. Childhood maltreatment was assessed using the Childhood Trauma Questionnaire-Short Form, and psychosocial health was measured using the Strengths and Difficulties Questionnaire (SDQ). Weighted linear mixed regression models, multiplicative interactions, and joint and mediation analyses were performed.Results: Of the 28,810 participants included (mean [SD] age, 19.87 [1.62] years), 12035 (41.8%) were male. In the fully adjusted model, participants who experienced parental migration were more likely to report higher levels of SDQ total difficulties (e.g. β = 0.16 [95% CI, 0.05 to 0.28]) compared with those with non-migrant parents. A positive association was found between the cumulative number of childhood maltreatment and SDQ total difficulties (β = 0.54 [95% CI, 0.49 to 0.60]), with a dose-response relationship observed for the levels of childhood maltreatment and SDQ total difficulties. Compared with individuals without exposure to both parental migration and childhood maltreatment, those exposed to both parental migration and at least 2 numbers of childhood maltreatment had the highest magnitude of psychosocial health difficulties (β = 1.12 [95% CI, 0.91 to 1.33]). Moreover, childhood maltreatment may partially mediate the association between parental migration and psychosocial health, with the mediation proportion being 58.8%.Conclusion: Exposure to parental labour migration or childhood maltreatment was positively associated with psychosocial health among adolescents and young adults. Parental migration and childhood maltreatment may jointly aggravate psychosocial health problems. These findings indicate the necessity of comprehensive interventions targeting adversity stressors to improve psychosocial health, especially for left-behind children experiencing maltreatment.

Epigenetics in persons living with HIV: trauma, coping, and FKBP5 and SLC6A4 methylation

AIM

People living with HIV (PLWH) have an increased risk for lifetime trauma and mental health difficulties. However, no studies have evaluated stress-related genes in relation to early-life adversity, lifetime trauma, or post-traumatic stress disorder (PTSD) in PLWH.

METHODS

Using bisulfite pyrosequencing, we evaluated DNA methylation (DNAm) in intron 7 of FKBP5, a glucocorticoid feedback regulator, and in the promoter of SLC6A4, the serotonin transporter gene, in whole blood of a random sample of 70 PLWH recruited from an HIV program, and 51 individuals 2 years later (n = 48 at both time points). Exploratory regression analyses were conducted with DNAm in relation to trauma exposure, mental health symptoms, and coping strategies.

RESULTS

Higher DNAm at one site of SLC6A4 was associated with lower levels of anxiety (B = -0.62 (SE = 0.23), p = 0.0109), depression (B = -0.06 (SE = 0.03), p = 0.0435), and PTSD symptoms at baseline (B = -0.03 (SE = 0.01), p = 0.0374). DNAm at FKBP5 was negatively associated with measures of anxiety (B = -0.30 (SE = 0.07), p = 0.0001) and depression symptoms (B = -0.2 (SE = 0.10), p = 0.0103). Various coping strategies were also associated with sites in both genes across time points, e.g. self-blame and substance use.

CONCLUSION

Our findings generate intriguing hypotheses linking mental health symptoms and DNA methylation, to be replicated with larger samples.

Molecular insights into trauma: A framework of epigenetic pathways to resilience through intervention

Experiences of complex trauma and adversity, especially for children, are ongoing global crises necessitating adaptation. Bioadaptability to adversity and its health consequences emphasizes the dynamism of adaptation to trauma and the potential for research to inform intervention strategies. Epigenetic variability, particularly DNA methylation, associates with chronic adversity while allowing for resilience and adaptability. Epigenetics, including age- and site-specific changes in DNA methylation, gene-environment interactions, pharmacological responses, and biomarker characterization and evaluation, may aid in understanding trauma responses and promoting well-being by facilitating psychological and biological adaptation. Understanding these molecular processes provides a foundation for a biologically adaptive framework to shift public health strategies from restorative to long-term adaptation and resilience. Psychological, cultural, and biological trauma must be addressed in innovative interventions for vulnerable populations, particularly children and adolescents. Understanding molecular changes may provide a biopsychosocial perspective for culturally sensitive, evidence-based interventions that promote resilience and thriving in new settings.

Adverse childhood experiences, mental distress, and autoimmune disease in adult women: findings from two large cohort studies

BACKGROUND

Adverse childhood experiences (ACEs) have been associated with increased risks of autoimmune diseases. However, data are scarce on the role of specific ACEs as well as the potential mediating role of adverse mental health symptoms in this association.

METHODS

A cohort study using the nationwide Icelandic Stress-And-Gene-Analysis (SAGA, 22,423 women) cohort and the UK Biobank (UKB, 86,492 women) was conducted. Participants self-reported on five ACEs. Twelve autoimmune diseases were self-reported in SAGA and identified via hospital records in UKB. Poisson regression was used to assess the cross-sectional association between ACEs and autoimmune diseases in both cohorts. Using longitudinal data on self-reported mental health symptoms in the UKB, we used causal mediation analyses to study potential mediation by depressive, anxiety, and PTSD symptoms in the association between ACEs and autoimmune diseases.

RESULTS

The prevalence of ACEs was 50% in SAGA and 35% in UKB, while the prevalence of autoimmune diseases was 29% (self-reported) and 14% (clinically confirmed), respectively. In both cohorts, ACEs were associated with an increased prevalence ratio (PR) of any studied autoimmune disease in a dose-response manner (PR = 1.10 (95%CI = 1.08-1.12) per ACE), particularly for Sjögrens (PR = 1.34), polymyalgia rheumatica (PR = 1.20), rheumatoid arthritis (PR = 1.14), systemic lupus erythematosus (PR = 1.13), and thyroid disease (PR = 1.11). Sexual abuse and physical and emotional neglect were consistently associated with an elevated prevalence of autoimmune diseases when including all ACEs in the model. Approximately one fourth of the association was mediated through depression, anxiety, and PTSD.

CONCLUSIONS

These findings based on two large cohorts indicate a role of ACEs and corresponding mental health distress in autoimmune diseases among adult women.

War Exposure and DNA Methylation in Syrian Refugee Children and Adolescents

Importance

Exposure to war is associated with poor mental health outcomes. Adverse and traumatic experiences can lead to long-lasting DNA methylation changes, potentially mediating the link between adversity and mental health. To date, limited studies have investigated the impact of war on DNA methylation in children or adolescents, hampering our understanding of the biological impact of war exposure.

Objective

To identify salivary DNA methylation differences associated with war exposure in refugee children and adolescents.

Design, Setting, and Participants

This cohort study included Syrian refugee children and adolescents, and their primary caregiver were recruited from tented settlements in Lebanon. Data collection was carried out in 2 waves, 1 year apart, from October 2017 to January 2018 and October 2018 to January 2019. Children and their caregiver were interviewed, and children provided saliva samples for DNA extraction. Data analysis was conducted in 2022, 2023, and 2024.

Exposure

War exposure assessed by interviewing children and their caregiver using the War Events Questionnaire.

Main Outcomes and Measures

Salivary DNA methylation levels were assayed with the Infinium MethylationEPIC BeadChip (Illumina). Epigenetic aging acceleration was estimated using a set of preexisting epigenetic aging clocks. A literature search was conducted to identify previously reported DNA methylation correlates of childhood trauma.

Results

The study population included 1507 children and adolescents (mean [SD] age, 11.3 [2.4] years; age range, 6-19 years; 793 female [52.6%]). A total of 1449 children provided saliva samples for DNA extraction in year 1, and 872 children provided samples in year 2. Children who reported war events had a number of differentially methylated sites and regions. Enrichment analyses indicated an enrichment of gene sets associated with transmembrane transport, neurotransmission, and intracellular movement in genes that exhibited differential methylation. Sex-stratified analyses found a number of sex-specific DNA methylation differences associated with war exposure. Only 2 of 258 (0.8%) previously reported trauma-associated DNA methylation sites were associated with war exposure (B = -0.004; 95% CI, -0.005 to -0.003; Bonferroni P = .04 and B = -0.005; 95% CI, -0.006 to -0.004; Bonferroni P = .03). Any war exposure or bombardment was nominally associated with decreased epigenetic age using the Horvath multitissue clock (B = -0.39; 95% CI, -0.63 to -0.14; P = .007 and B = -0.42; 95% CI, -0.73 to -0.11; P = .002).

Conclusions and Relevance

In this cohort of Syrian refugee children and adolescents, war exposure was associated with a small number of distinct differences in salivary DNA methylation.

Epigenome-wide mediation analysis of the relationship between psychosocial stress and cardiometabolic risk factors in the Health and Retirement Study (HRS)

BACKGROUND

Exposure to psychosocial stress is linked to a variety of negative health outcomes, including cardiovascular disease and its cardiometabolic risk factors. DNA methylation has been associated with both psychosocial stress and cardiometabolic disease; however, little is known about the mediating role of DNA methylation on the association between stress and cardiometabolic risk. Thus, using the high-dimensional mediation testing method, we conducted an epigenome-wide mediation analysis of the relationship between psychosocial stress and ten cardiometabolic risk factors in a multi-racial/ethnic population of older adults (n = 2668) from the Health and Retirement Study (mean age = 70.4 years).

RESULTS

A total of 50, 46, 7, and 12 CpG sites across the epigenome mediated the total effects of stress on body mass index, waist circumference, high-density lipoprotein cholesterol, and C-reactive protein, respectively. When reducing the dimensionality of the CpG mediators to their top 10 uncorrelated principal components (PC), the cumulative effect of the PCs explained between 35.8 and 46.3% of these associations.

CONCLUSIONS

A subset of the mediating CpG sites were associated with the expression of genes enriched in pathways related to cytokine binding and receptor activity, as well as neuron development. Findings from this study help to elucidate the underlying mechanisms through which DNA methylation partially mediates the relationship between psychosocial stress and cardiometabolic risk factors.

Epigenome-wide association study of long-term psychosocial stress in older adults

Long-term psychosocial stress is strongly associated with negative physical and mental health outcomes, as well as adverse health behaviours; however, little is known about the role that stress plays on the epigenome. One proposed mechanism by which stress affects DNA methylation is through health behaviours. We conducted an epigenome-wide association study (EWAS) of cumulative psychosocial stress (n = 2,689) from the Health and Retirement Study (mean age = 70.4 years), assessing DNA methylation (Illumina Infinium HumanMethylationEPIC Beadchip) at 789,656 CpG sites. For identified CpG sites, we conducted a formal mediation analysis to examine whether smoking, alcohol use, physical activity, and body mass index (BMI) mediate the relationship between stress and DNA methylation. Nine CpG sites were associated with psychosocial stress (all p < 9E-07; FDR q < 0.10). Additionally, health behaviours and/or BMI mediated 9.4% to 21.8% of the relationship between stress and methylation at eight of the nine CpGs. Several of the identified CpGs were in or near genes associated with cardiometabolic traits, psychosocial disorders, inflammation, and smoking. These findings support our hypothesis that psychosocial stress is associated with DNA methylation across the epigenome. Furthermore, specific health behaviours mediate only a modest percentage of this relationship, providing evidence that other mechanisms may link stress and DNA methylation.

Mediation of DNA methylation (cg04622888 and cg05037505) in the association between childhood maltreatment and non-suicidal self-injury in early adolescents

It is unclear whether DNA methylation underlies the association between childhood maltreatment (CM) and non-suicidal self-injury (NSSI) in early adolescents. We aim to explore the mediation of specific DNA methylation sites in the associations of CM and its subtypes with NSSI, following investigation on the association between specific DNA methylation sites and NSSI. A case-control study was conducted to examine 155 adolescents aged 12-14 years who were identified to have engaged in NSSI and 201 controls. CM and its subtypes were evaluated by using the Childhood Trauma Questionnaire. The EPIC 850 k Bead Chip was used to discover differential methylation sites (DMSs) in the peripheral blood between 10 NSSI cases and 10 controls. Targeted pyrosequencing was employed to detect the levels of specific DMSs among the total study population, which were selected based on bioinformatics analyses and literature review. We discovered 456 DMSs between NSSI cases and controls, 219 were hypermethylated and 237 were hypomethylated. After controlling for potential confounders, CM or its subtypes, and the methylation of cg04622888 and cg05037505 were all significantly associated with NSSI (all P < 0.05). The total association of CM and its subtypes with NSSI were all significantly (all P < 0.05), with the standardized coefficient (β) ranged from 0.12 for physical neglect to 0.24 for emotional neglect and CM. Significant indirect association of physical neglect with NSSI through methylation of cg04622888 was observed and the mediating proportion was 0.14 (95%CI 0.06-0.23). Significant indirect associations of emotional abuse, emotional neglect, and physical neglect with NSSI through methylation of cg05037505 were also observed, and the mediating proportions were 0.09 (95%CI 0.04-0.14), 0.08 (95%CI, 0.03-0.14) and 0.19 (95%CI 0.07-0.32), respectively. Data of this study suggested that methylation of cg04622888 and cg05037505 were independently associated with NSSI among early adolescents, and they partially mediated the associations of emotional abuse, emotional neglect, and physical abuse with NSSI.

Towards a Novel Frontier in the Use of Epigenetic Clocks in Epidemiology

Health problems associated with aging are a major public health concern for the future. Aging is a complex process with wide intervariability among individuals. Therefore, there is a need for innovative public health strategies that target factors associated with aging and the development of tools to assess the effectiveness of these strategies accurately. Novel approaches to measure biological age, such as epigenetic clocks, have become relevant. These clocks use non-sequential variable information from the genome and employ mathematical algorithms to estimate biological age based on DNA methylation levels. Therefore, in the present study, we comprehensively review the current status of the epigenetic clocks and their associations across the human phenome. We emphasize the potential utility of these tools in an epidemiological context, particularly in evaluating the impact of public health interventions focused on promoting healthy aging. Our review describes associations between epigenetic clocks and multiple traits across the life and health span. Additionally, we highlighted the evolution of studies beyond mere associations to establish causal mechanisms between epigenetic age and disease. We explored the application of epigenetic clocks to measure the efficacy of interventions focusing on rejuvenation.

DNA methylation signatures of early-life adversity are exposure-dependent in wild baboons

The early-life environment can profoundly shape the trajectory of an animal's life, even years or decades later. One mechanism proposed to contribute to these early-life effects is DNA methylation. However, the frequency and functional importance of DNA methylation in shaping early-life effects on adult outcomes is poorly understood, especially in natural populations. Here, we integrate prospectively collected data on fitness-associated variation in the early environment with DNA methylation estimates at 477,270 CpG sites in 256 wild baboons. We find highly heterogeneous relationships between the early-life environment and DNA methylation in adulthood: aspects of the environment linked to resource limitation (e.g., low-quality habitat, early-life drought) are associated with many more CpG sites than other types of environmental stressors (e.g., low maternal social status). Sites associated with early resource limitation are enriched in gene bodies and putative enhancers, suggesting they are functionally relevant. Indeed, by deploying a baboon-specific, massively parallel reporter assay, we show that a subset of windows containing these sites are capable of regulatory activity, and that, for 88% of early drought-associated sites in these regulatory windows, enhancer activity is DNA methylation-dependent. Together, our results support the idea that DNA methylation patterns contain a persistent signature of the early-life environment. However, they also indicate that not all environmental exposures leave an equivalent mark and suggest that socioenvironmental variation at the time of sampling is more likely to be functionally important. Thus, multiple mechanisms must converge to explain early-life effects on fitness-related traits.

Effect of parental adverse childhood experiences on intergenerational DNA methylation signatures from peripheral blood mononuclear cells and buccal mucosa

In this study, the effect of cumulative ACEs experienced on human maternal DNA methylation (DNAm) was estimated while accounting for interaction with domains of ACEs in prenatal peripheral blood mononuclear cell samples from the Maternal and Developmental Risks from Environmental Stressors (MADRES) pregnancy cohort. The intergenerational transmission of ACE-associated DNAm was also explored used paired maternal (N = 120) and neonatal cord blood (N = 69) samples. Replication in buccal samples was explored in the Children's Health Study (CHS) among adult parental (N = 31) and pediatric (N = 114) samples. We used a four-level categorical indicator variable for ACEs exposure: none (0 ACEs), low (1-3 ACEs), moderate (4-6 ACEs), and high (>6 ACEs). Effects of ACEs on maternal DNAm (N = 240) were estimated using linear models. To evaluate evidence for intergenerational transmission, mediation analysis (N = 60 mother-child pairs) was used. Analysis of maternal samples displayed some shared but mostly distinct effects of ACEs on DNAm across low, moderate, and high ACEs categories. CLCN7 and PTPRN2 was associated with maternal DNAm in the low ACE group and this association replicated in the CHS. CLCN7 was also nominally significant in the gene expression correlation analysis among maternal profiles (N = 35), along with 11 other genes. ACE-associated methylation was observed in maternal and neonatal profiles in the COMT promoter region, with some evidence of mediation by maternal COMT methylation. Specific genomic loci exhibited mutually exclusive maternal ACE effects on DNAm in either maternal or neonatal population. There is some evidence for an intergenerational effect of ACEs, supported by shared DNAm signatures in the COMT gene across maternal-neonatal paired samples.

Adverse childhood experiences and psychological functioning among women with schizophrenia or bipolar disorder: population-based study

BACKGROUND

Adverse childhood experiences (ACEs) are well-known risk factors for schizophrenia and bipolar disorder.

AIMS

The aim was to study the associations between specific ACEs and psychological functioning in women with schizophrenia or bipolar disorder.

METHOD

Among 29 367 women (mean age 44 years) from the Icelandic Stress-And-Gene-Analysis (SAGA) study, 534 (1.8%, mean age 40) reported having been diagnosed with schizophrenia or bipolar disorder, which were combined to 'severe mental disorders'. Participants reported on 13 types of ACEs, childhood deprivation and psychological functioning (defined as coping ability and current symptoms of depression, anxiety and sleep disturbances). Adjusted Poisson regression calculated prevalence ratios (PRs) between ACEs and severe mental disorders. Linear regression assessed the association between ACEs and psychological functioning among women with a severe mental disorder.

RESULTS

Women with a severe mental disorder reported more ACEs (mean 4.57, s.d. = 2.82) than women without (mean 2.51, s.d. = 2.34) in a dose-dependent manner (fully-adjusted PR = 1.23 per ACE, 95% CI 1.20-1.27). After mutual adjustment for other ACEs, emotional abuse, sexual abuse, mental illness of a household member, emotional neglect, bullying and collective violence were associated with severe mental disorders. Among women with severe mental disorders, a higher number of ACEs was associated with increased symptom burden of depression (β = 2.79, 95% CI = 1.19-4.38) and anxiety (β = 2.04, 95% CI = 0.99-3.09) including poorer sleep quality (β = 0.83, 95% CI = 0.07-1.59). Findings were similar for schizophrenia and bipolar disorder separately.

CONCLUSION

Women with schizophrenia or bipolar disorder show a strong history of ACEs, which may interfere with their psychological functioning and, therefore, need to be addressed as part of their treatment, for example, with trauma-focused psychotherapy.

Maternal adverse childhood experiences (ACEs) and DNA methylation of newborns in cord blood

BACKGROUND

Adverse childhood experiences (ACEs) increase the risk of poor health outcomes later in life. Psychosocial stressors may also have intergenerational health effects by which parental ACEs are associated with mental and physical health of children. Epigenetic programming may be one mechanism linking parental ACEs to child health. This study aimed to investigate epigenome-wide associations of maternal preconception ACEs with DNA methylation patterns of children. In the Center for the Health Assessment of Mothers and Children of Salinas study, cord blood DNA methylation was measured using the Illumina HumanMethylation450 BeadChip. Preconception ACEs, which occurred during the mothers' childhoods, were collected using a standard ACE questionnaire including 10 ACE indicators. Maternal ACE exposures were defined in this study as (1) the total number of ACEs; (2) the total number of ACEs categorized as 0, 1-3, and > 4; and (3) individual ACEs. Associations of ACE exposures with differential methylated positions, regions, and CpG modules determined using weighted gene co-expression network analysis were evaluated adjusting for covariates.

RESULTS

Data on maternal ACEs and cord blood DNA methylation were available for 196 mother/newborn pairs. One differential methylated position was associated with maternal experience of emotional abuse (cg05486260/FAM135B gene; q value < 0.05). Five differential methylated regions were significantly associated with the total number of ACEs, and 36 unique differential methylated regions were associated with individual ACEs (Šidák p value < 0.05). Fifteen CpG modules were significantly correlated with the total number of ACEs or individual ACEs, of which 8 remained significant in fully adjusted models (p value < 0.05). Significant modules were enriched for pathways related to neurological and immune development and function.

CONCLUSIONS

Maternal ACEs prior to conception were associated with cord blood DNA methylation of offspring at birth. Although there was limited overlap between differential methylated regions and CpGs in modules associated with ACE exposures, statistically significant regions and networks were related to genes involved in neurological and immune function. Findings may provide insights to pathways linking psychosocial stressors to health. Further research is needed to understand the relationship between changes in DNA methylation and child health.

Stage 2 Registered Report: Epigenetic Intergenerational Transmission: Mothers' Adverse Childhood Experiences and DNA Methylation

OBJECTIVE

Individual differences in risk for mental disorders over the lifespan are shaped by forces acting before the individual is born-in utero, but likely even earlier, during the mother's own childhood. The environmental epigenetics hypothesis proposes that sustained effects of environmental conditions on gene expression are mediated by epigenetic mechanisms. Recent human studies have shown that adversities in childhood are correlated with DNA methylation (DNAm) in adulthood. In the current study, we tested the following pre-registered hypotheses: Mothers' adverse childhood experiences (ACEs) are correlated with DNAm in peripheral blood during pregnancy (hypothesis 1) and in cord blood samples from newborn infants (hypothesis 2), and women's depression and anxiety symptoms during pregnancy mediate the association between mothers' ACE exposure and prenatal/neonatal DNA methylation (hypothesis 3).

METHOD

Data were from the Avon Longitudinal Study of Parents and Children Accessible Resource for Integrated Epigenomic Studies substudy. Women provided retrospective self-reports during pregnancy of ACE exposure. We conducted an epigenome-wide association study testing whether mothers' ACE exposure, cumulative score (0-10), was associated with DNAm in maternal antenatal blood and infant cord blood in more than 450,000 CpG (point on DNA sequence where cytosine and guanine base pairs are linked by a phosphate, where methylation usually occurs) sites on the Illumina 450K BeadChip. Analyses for cord blood were separated by infant sex, a pre-registered analysis.

RESULTS

Hypothesis 1: In 896 mother-infant pairs with available methylation and ACE exposure data, there were no significant associations between mothers' ACE score and DNAm from antenatal peripheral blood, after controlling for covariates. Hypothesis 2: In infant cord blood, there were 5 CpG sites significantly differentially methylated in relation to mothers' ACEs (false discovery rate [FDR] < .05), but only in male offspring. Effect sizes were medium, with partial eta squared values ranging from 0.060 to 0.078. CpG sites were in genes related to mitochondrial function and neuronal development in the cerebellum. Hypothesis 3: There was no mediation by maternal anxiety/depression symptoms found between mothers' ACEs score and DNAm in the significant CpG sites in male cord blood. Mediation was not tested in antenatal peripheral blood, because no direct association between mothers' ACE score and antenatal peripheral blood was found.

CONCLUSION

Our results show that mothers' ACE exposure is associated with DNAm in male offspring, supporting the notion that DNAm could be a marker of intergenerational biological embedding of mothers' childhood adversity.

STUDY REGISTRATION INFORMATION

Epigenetic Intergenerational Transmission: Mothers' Adverse Childhood Experiences and DNA Methylation; https://doi.org/10.1016/j.jaac.2020.03.008.

Association between gene methylation and experiences of historical trauma in Alaska Native peoples

BACKGROUND

Historical trauma experienced by Indigenous peoples of North America is correlated with health disparities and is hypothesized to be associated with DNA methylation. Massive group traumas such as genocide, loss of land and foodways, and forced conversion to Western lifeways may be embodied and affect individuals, families, communities, cultures, and health. This study approaches research with Alaska Native people using a community-engaged approach designed to create mutually-beneficial partnerships, including intentional relationship development, capacity building, and sample and data care.

METHODS

A total of 117 Alaska Native individuals from two regions of Alaska joined the research study. Participants completed surveys on cultural identification, historical trauma (historical loss scale and historical loss associated symptoms scale), and general wellbeing. Participants provided a blood sample which was used to assess DNA methylation with the Illumina Infinium MethylationEPIC array.

RESULTS

We report an association between historical loss associated symptoms and DNA methylation at five CpG sites, evidencing the embodiment of historical trauma. We further report an association between cultural identification and general wellbeing, complementing evidence from oral narratives and additional studies that multiple aspects of cultural connection may buffer the effects of and/or aid in the healing process from historical trauma.

CONCLUSION

A community-engaged approach emphasizes balanced partnerships between communities and researchers. Here, this approach helps better understand embodiment of historical trauma in Alaska Native peoples. This analysis reveals links between the historical trauma response and DNA methylation. Indigenous communities have been stigmatized for public health issues instead caused by systemic inequalities, social disparities, and discrimination, and we argue that the social determinants of health model in Alaska Native peoples must include the vast impact of historical trauma and ongoing colonial violence.

Social and early life determinants of survival from cradle to grave: A case study in wild baboons

Field studies of natural mammal populations present powerful opportunities to investigate the determinants of health and aging using fine-grained observations of known individuals across the life course. Here, we synthesize five decades of findings from one such study: the wild baboons of the Amboseli ecosystem in Kenya. First, we discuss the profound associations between early life adversity, adult social conditions, and key aging outcomes in this population, especially survival. Second, we review potential mediators of the relationship between early life adversity and survival in our population. Notably, our tests of two leading candidate mediators-social isolation and glucocorticoid levels-fail to identify a single, strong mediator of early life effects on adult survival. Instead, early adversity, social isolation, and glucocorticoids are independently linked to adult lifespans, suggesting considerable scope for mitigating the negative consequences of early life adversity. Third, we review our work on the evolutionary rationale for early life effects on mortality, which currently argues against clear predictive adaptive responses. Finally, we end by highlighting major themes emerging from the study of sociality, development, and aging in the Amboseli baboons, as well as important open questions for future work.

Epigenetic clocks and research implications of the lack of data on whom they have been developed: a review of reported and missing sociodemographic characteristics

Epigenetic clocks are increasingly being used as a tool to assess the impact of a wide variety of phenotypes and exposures on healthy ageing, with a recent focus on social determinants of health. However, little attention has been paid to the sociodemographic characteristics of participants on whom these clocks have been based. Participant characteristics are important because sociodemographic and socioeconomic factors are known to be associated with both DNA methylation variation and healthy ageing. It is also well known that machine learning algorithms have the potential to exacerbate health inequities through the use of unrepresentative samples - prediction models may underperform in social groups that were poorly represented in the training data used to construct the model. To address this gap in the literature, we conducted a review of the sociodemographic characteristics of the participants whose data were used to construct 13 commonly used epigenetic clocks. We found that although some of the epigenetic clocks were created utilizing data provided by individuals from different ages, sexes/genders, and racialized groups, sociodemographic characteristics are generally poorly reported. Reported information is limited by inadequate conceptualization of the social dimensions and exposure implications of gender and racialized inequality, and socioeconomic data are infrequently reported. It is important for future work to ensure clear reporting of tangible data on the sociodemographic and socioeconomic characteristics of all the participants in the study to ensure that other researchers can make informed judgements about the appropriateness of the model for their study population.

Effect of Parental Adverse Childhood Experiences on Intergenerational DNA Methylation Signatures

Adverse Childhood Experiences (ACEs) are events that occur before a child turns 18 years old that may cause trauma. In this study, the effect of cumulative ACEs experienced on human maternal DNA methylation (DNAm) was estimated while accounting for interaction with domains of ACEs in prenatal peripheral blood mononuclear cell samples from the Maternal and Developmental Risks from Environmental Stressors (MADRES) pregnancy cohort. The intergenerational transmission of ACE-associated DNAm was also explored used paired maternal and neonatal cord blood samples. Replication in buccal samples was explored in the Children's Health Study (CHS). We used a four-level categorical indicator variable for ACEs exposure: none (0 ACEs), low (1-3 ACEs), moderate (4-6 ACEs), and high (> 6 ACEs). Effects of ACEs on maternal DNAm (N = 240) were estimated using linear models. To evaluate evidence for intergenerational transmission, mediation analysis was used. Analysis of maternal samples displayed some shared but mostly distinct effects of ACEs on DNAm across low, moderate, and high ACEs categories. CLCN7 and PTPRN2 was associated with maternal DNAm in the low ACE group and this association replicated in the CHS. ACE-associated methylation was observed in maternal and neonatal profiles in the COMT promoter region, with some evidence of mediation by maternal COMT methylation. Specific genomic loci exhibited mutually exclusive maternal ACE effects on DNAm in either maternal or neonatal population. There is some evidence for an intergenerational effect of ACEs, supported by shared DNAm signatures in the COMT gene across maternal-neonatal paired samples.

Childhood maltreatment and DNA methylation: A systematic review

Child maltreatment (CM) encompasses sexual abuse, physical abuse, emotional abuse, neglect, and exposure to domestic and family violence. Epigenetic research investigating CM has focused on differential DNA methylation (DNAm) in genes associated with the stress response, but there has been limited evaluation of the specific effects of subtypes of CM. This systematic review of literature investigating DNAm associated with CM in non-clinical populations aimed to summarise the approaches currently used in research, how the type of maltreatment and age of exposure were encoded via methylation, and which genes have consistently been associated with CM. A total of fifty-four papers were eligible for review, including forty-one candidate gene studies, eight epigenome-wide association studies, and five studies with a mixed design. The ways in which the various forms of CM were conceptualised and measured varied between papers. Future studies would benefit from assessments that employ conceptually robust definitions of CM, and that capture important contextual information such as age of exposure and subtype of CM.

Investigating the effects of maltreatment and acute stress on the concordance of blood and DNA methylation methods of estimating immune cell proportions

BACKGROUND

Immune cell proportions can be used to detect pathophysiological states and are also critical covariates in genomic analyses. The complete blood count (CBC) is the most common method of immune cell proportion estimation, but immune cell proportions can also be estimated using whole-genome DNA methylation (DNAm). Although the concordance of CBC and DNAm estimations has been validated in various adult and clinical populations, less is known about the concordance of existing estimators among stress-exposed individuals. As early life adversity and acute psychosocial stress have both been associated with unique DNAm alterations, the concordance of CBC and DNAm immune cell proportion needs to be validated in various states of stress.

RESULTS

We report the correlation and concordance between CBC and DNAm estimates of immune cell proportions using the Illumina EPIC DNAm array within two unique studies: Study 1, a high-risk pediatric cohort of children oversampled for exposure to maltreatment (N = 365, age 8 to 14 years), and Study 2, a sample of young adults who have participated in an acute laboratory stressor with four pre- and post-stress measurements (N = 28, number of observations = 100). Comparing CBC and DNAm proportions across both studies, estimates of neutrophils (r = 0.948, p < 0.001), lymphocytes (r = 0.916, p < 0.001), and eosinophils (r = 0.933, p < 0.001) were highly correlated, while monocyte estimates were moderately correlated (r = 0.766, p < 0.001) and basophil estimates were weakly correlated (r = 0.189, p < 0.001). In Study 1, we observed significant deviations in raw values between the two approaches for some immune cell subtypes; however, the observed differences were not significantly predicted by exposure to child maltreatment. In Study 2, while significant changes in immune cell proportions were observed in response to acute psychosocial stress for both CBC and DNAm estimates, the observed changes were similar for both approaches.

CONCLUSIONS

Although significant differences in immune cell proportion estimates between CBC and DNAm exist, as well as stress-induced changes in immune cell proportions, neither child maltreatment nor acute psychosocial stress alters the concordance of CBC and DNAm estimation methods. These results suggest that the agreement between CBC and DNAm estimators of immune cell proportions is robust to exposure to child maltreatment and acute psychosocial stress.

Hypermethylation of the serotonin transporter gene and paternal parenting styles in untreated anorexia nervosa patients: A pilot study

Purpose

It has been reported that serotonergic systems and parenting styles are involved in the pathogenesis of anorexia nervosa (AN). The present study made attempts to examine the DNA methylation profiles in the promoter region of serotonin transporter (5-HTT) encoding gene SLC6A4, and explore the association between the methylation level and severity of symptoms, 5-HTT linked polymorphic region (5-HTTLPR) genotypes and parenting styles in untreated Chinese Han AN patients.

Methods

Ninety-one untreated female AN patients (ANs) and eighty-seven matched healthy controls (HCs) were analyzed for DNA methylation status at CpG islands in the promoter region of SLC6A4 using MassARRY EpiTYPER, and genotypes of 5-HTTLPR using PCR-RFLP. The severity of eating disorder (ED) symptoms was evaluated by body mass index (BMI) and Questionnaire Version of the Eating Disorders Examination (EDE-Q 6.0), and part of participants were assessed parenting styles using the short Chinese Egna Minnen av Barndoms Uppfostra (s-EMBU-C).

Results

ANs had greater methylation levels at CpG26.27.28, CpG 31.32, and CpG 37 than HCs (P = 0.039, 0.042, 0.018 respectively). A positive association of methylation level at CpG26.27.28 with ED symptoms detected by EDEQ-6.0 was discovered in AN group (r = 0.216, P = 0.047). Methylation level at CpG26.27.28 was showed to be or tend to be positively correlated with the parenting styles of paternal rejection (r = 0.425, P = 0.038) and paternal overprotection (r = 0.362, P = 0.062) in ANs. No significant differences were found in SLC6A4 promoter region methylation levels among 5-HTTLPR genotypes in our samples (P > 0.05) and no interaction effect between 5-HTTLPR genotypes and parenting styles on SLC6A4 promoter region methylation was observed (P > 0.05).

Conclusions

This study suggested that hypermethylation of SLC6A4 promoter region may be implicated in the pathological mechanisms of untreated Chinese Han female ANs, which is possibly associated with poor parenting styles. This finding may provide a direction for the epigenetic and family treatments for ANs and further investigation with larger samples is warranted.

Epigenetics as a Biomarker for Early-Life Environmental Exposure

PURPOSE OF REVIEW

There is interest in evaluating the developmental origins of health and disease (DOHaD) which emphasizes the role of prenatal and early-life environments on non-communicable health outcomes throughout the life course. The ability to rigorously assess and identify early-life risk factors for later health outcomes, including those with childhood onset, in large population samples is often limited due to measurement challenges such as impractical costs associated with prospective studies with a long follow-up duration, short half-lives for some environmental toxicants, and lack of biomarkers that capture inter-individual differences in biologic response to external environments.

RECENT FINDINGS

Epigenomic patterns, and DNA methylation in particular, have emerged as a potential objective biomarker to address some of these study design and exposure measurement challenges. In this article, we summarize the literature to date on epigenetic changes associated with specific prenatal and early-life exposure domains as well as exposure mixtures in human observational studies and their biomarker potential. Additionally, we highlight evidence for other types of epigenetic patterns to serve as exposure biomarkers. Evidence strongly supports epigenomic biomarkers of exposure that are detectable across the lifespan and across a range of exposure domains. Current and future areas of research in this field seek to expand these lines of evidence to other environmental exposures, to determine their specificity, and to develop predictive algorithms and methylation scores that can be used to evaluate early-life risk factors for health outcomes across the life span.

Childhood Trauma and Epigenetics: State of the Science and Future

PURPOSE OF REVIEW

There is a great deal of interest regarding the biological embedding of childhood trauma and social exposures through epigenetic mechanisms, including DNA methylation (DNAm), but a comprehensive understanding has been hindered by issues of limited reproducibility between studies. This review presents a summary of the literature on childhood trauma and DNAm, highlights issues in the field, and proposes some potential solutions.

RECENT FINDINGS

Investigations of the associations between DNAm and childhood trauma are commonly performed using candidate gene approaches, specifically involving genes related to neurological and stress pathways. Childhood trauma is defined in a wide range of ways in several societal contexts. However, although variations in DNAm are frequently found in stress-related genes, unsupervised epigenome-wide association studies (EWAS) have shown limited reproducibility both between studies and in relating these changes to exposures. The reproducibility of childhood trauma DNAm studies, and the field of social epigenetics in general, may be improved by increasing sample sizes, standardizing variables, making use of effect size thresholds, collecting longitudinal and intervention samples, appropriately accounting for known confounding factors, and applying causal analysis wherever possible, such as "two-step epigenetic Mendelian randomization."

An epigenetic association analysis of childhood trauma in psychosis reveals possible overlap with methylation changes associated with PTSD

Patients with a severe mental disorder report significantly higher levels of childhood trauma (CT) than healthy individuals. Studies have suggested that CT may affect brain plasticity through epigenetic mechanisms and contribute to developing various psychiatric disorders. We performed a blood-based epigenome-wide association study using the Childhood Trauma Questionnaire-short form in 602 patients with a current severe mental illness, investigating DNA methylation association separately for five trauma subtypes and the total trauma score. The median trauma score was set as the predefined cutoff for determining whether the trauma was present or not. Additionally, we compared our genome-wide results with methylation probes annotated to candidate genes previously associated with CT. Of the patients, 83.2% reported CT above the cutoff in one or more trauma subtypes, and emotional neglect was the trauma subtype most frequently reported. We identified one significant differently methylated position associated with the gene TANGO6 for physical neglect. Seventeen differentially methylated regions (DMRs) were associated with different trauma categories. Several of these DMRs were annotated to genes previously associated with neuropsychiatric disorders such as post-traumatic stress disorder and cognitive impairments. Our results support a biomolecular association between CT and severe mental disorders. Genes that were previously identified as differentially methylated in CT-exposed subjects with and without psychosis did not show methylation differences in our analysis. We discuss this inconsistency, the relevance of our findings, and the limitations of our study.

Epigenetics of early-life adversity in youth: cross-sectional and longitudinal associations

BACKGROUND

Altered DNA methylation (DNAm) may be one pathway through which early-life adversity (ELA) contributes to adverse mental and physical health outcomes. This study investigated whether the presence versus absence of ELA experiences reflecting the dimensions of threat and deprivation were associated with epigenome-wide DNAm cross-sectionally and longitudinally in a community-based sample of children and adolescents.

METHODS

In 113 youths aged 8-16 years with wide variability in ELA, we examined associations of abuse (physical, sexual, emotional; indicating threat-related experiences) and neglect (emotional, physical; indicating deprivation-related experiences) with DNAm assessed with the Illumina EPIC BeadChip array, with DNA derived from saliva. In cross-sectional epigenome-wide analyses, we investigated associations of lifetime abuse and neglect with DNAm at baseline. In longitudinal epigenome-wide analyses, we examined whether experiencing abuse and neglect over an approximately 2-year follow-up were each associated with change in DNAm from baseline to follow-up.

RESULTS

In cross-sectional analyses adjusting for lifetime experience of neglect, lifetime experience of abuse was associated with DNAm for four cytosine-phosphodiester-guanine (CpG) sites (cg20241299: coefficient = 0.023, SE = 0.004; cg08671764: coefficient = 0.018, SE = 0.003; cg27152686: coefficient = - 0.069, SE = 0.012; cg24241897: coefficient = - 0.003, SE = 0.001; FDR < .05). In longitudinal analyses, experiencing neglect over follow-up was associated with an increase in DNAm for one CpG site, adjusting for abuse over follow-up (cg03135983: coefficient = 0.036, SE = 0.006; FDR < .05).

CONCLUSIONS

In this study, we identified examples of epigenetic patterns associated with ELA experiences of threat and deprivation that were already observable in youth. We provide novel evidence for change in DNAm over time in relation to ongoing adversity and that experiences reflecting distinct ELA dimensions may be characterized by unique epigenetic patterns.

Understanding Health Inequalities Through the Lens of Social Epigenetics

Longstanding racial/ethnic inequalities in morbidity and mortality persist in the United States. Although the determinants of health inequalities are complex, social and structural factors produced by inequitable and racialized systems are recognized as contributing sources. Social epigenetics is an emerging area of research that aims to uncover biological pathways through which social experiences affect health outcomes. A growing body of literature links adverse social exposures to epigenetic mechanisms, namely DNA methylation, offering a plausible pathway through which health inequalities may arise. This review provides an overview of social epigenetics and highlights existing literature linking social exposures-i.e., psychosocial stressors, racism, discrimination, socioeconomic position, and neighborhood social environment-to DNA methylation in humans. We conclude with a discussion of social epigenetics as a mechanistic link to health inequalities and provide suggestions for future social epigenetics research on health inequalities.

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.

Adulthood asthma as a consequence of childhood adversity: a systematic review of epigenetically affected genes

There is an accumulating data that shows relation between childhood adversity and vulnerability to chronic diseases as well as epigenetic influences that in turn give rise to these diseases. Asthma is one of the chronic diseases that is influenced from genetic regulation of the inflammatory biomolecules and therefore the hypothesis in this research was childhood adversity might have caused epigenetic differentiation in the asthma-related genes in the population who had childhood trauma. To test this hypothesis, the literature was systematically reviewed to extract epigenetically modified gene data of the adults who had childhood adversity, and affected genes were further evaluated for their association with asthma. PRISMA guidelines were adopted and PubMed and Google Scholar were included in the searched databases, to evaluate epigenetic modifications in asthma-related genes of physically, emotionally or sexually abused children. After retrieving a total of 5245 articles, 36 of them were included in the study. Several genes and pathways that may contribute to pathogenesis of asthma development, increased inflammation, or response to asthma treatment were found epigenetically affected by childhood traumas. Childhood adversity, causing epigenetic changes in DNA, may lead to asthma development or influence the course of the disease and therefore should be taken into account for the prolonged health consequences.

Addressing the biological embedding of early life adversities (ELA) among adults through mindfulness: Proposed mechanisms and review of converging evidence

Early life adversities (ELA) are prevalent and have a profound and adverse impact across the lifespan, including on age-related health outcomes, yet interventions to remediate its adverse impact are scarce. This paper presents evidence for mindfulness training to reduce the elevated mental and physical health risks linked to ELA among adults by targeting biological mechanisms of ELA leading to these adverse health outcomes. We first provide a brief overview of ELA, its adverse health impacts, and mechanisms that might be responsible. Next, we review converging evidence that demonstrates that mindfulness training influences key biological pathways involved in ELA-linked negative health consequences, including (a) brain networks involved in self-regulation, (b) immunity and inflammation, (c) telomere biology, and (d) epigenetic modifications. Further, we review preliminary evidence from mindfulness-based trials that focused on populations impacted by ELA. We discuss limitations of this review and provide recommendations for future research. If effective, a mindfulness-based approach could be an important public health strategy for remediating the adverse mental and physical health consequences of ELA.

Infant DNA methylation: an early indicator of intergenerational trauma?

Exposure to adverse childhood experiences (ACEs) increases risk for mental and physical health problems. Intergenerationally, mothers' ACEs predict children's health problems including neurodevelopmental and behavioural problems and poorer physical health. Theories of intergenerational trauma suggest that ACEs experienced in one generation negatively affect the health and well-being of future generations, with DNA methylation (DNAm) being one of several potential biological explanations. To begin exploring this hypothesis, we tested whether infant DNA methylation associated with intergenerational trauma. Secondary analysis employed data from the Alberta Pregnancy Outcomes and Nutrition (APrON) study. Subsample data were collected from mothers during pregnancy and postpartum on measures of distress, stress and ACEs and from infants at 3 months of age on DNAm from blood (n = 92) and buccal epithelial cells (BECs; n = 124; primarily nonoverlapping individuals between tissues). Blood and BECs were examined in separate analyses. Preliminary associations identified in blood and BECs suggest that infant DNAm patterns may relate to maternal ACEs. For the majority of ACE-related DNAm sites, neither maternal perinatal distress, nor maternal cortisol awakening response (CAR; a measure of hypothalamic-pituitary-adrenocortical axis function), substantially reduced associations between maternal ACEs and infant DNAm. However, accounting for maternal perinatal distress and cortisol substantially changed the effect of ACEs in a greater proportion of blood DNAm sites than BEC DNAm sites in the top ACEs-associated correlated methylated regions (CMRs), as well as across all CMRs and all remaining CpGs (that did not fall into CMRs). Possible DNAm patterns in infants, thus, might capture a signature of maternal intergenerational trauma, and this effect appears to be more dependent on maternal perinatal distress and CAR in blood relative to BECs.

Maternal adverse childhood experiences before pregnancy are associated with epigenetic aging changes in their children

Emerging research suggests associations of physical and psychosocial stressors with epigenetic aging. Although this work has included early-life exposures, data on maternal exposures and epigenetic aging of their children remain sparse. Using longitudinally collected data from the California, Salinas Valley CHAMACOS study, we examined relationships between maternal Adverse Childhood Experiences (ACEs) reported up to 18 years of life, prior to pregnancy, with eight measures (Horvath, Hannum, SkinBloodClock, Intrinsic, Extrinsic, PhenoAge, GrimAge, and DNAm telomere length) of blood leukocyte epigenetic age acceleration (EAA) in their children at ages 7, 9, and 14 years (N = 238 participants with 483 observations). After adjusting for maternal chronological age at delivery, pregnancy smoking/alcohol use, parity, child gestational age, and estimated leukocyte proportions, higher maternal ACEs were significantly associated with at least a 0.76-year increase in child Horvath and Intrinsic EAA. Higher maternal ACEs were also associated with a 0.04 kb greater DNAm estimate of telomere length of children. Overall, our data suggests that maternal preconception ACEs are associated with biological aging in their offspring in childhood and that preconception ACEs have differential relationships with EAA measures, suggesting different physiologic utilities of EEA measures. Studies are necessary to confirm these findings and to elucidate potential pathways to explain these relationships, which may include intergenerational epigenetic inheritance and persistent physical and social exposomes.

Childhood adversity correlates with stable changes in DNA methylation trajectories in children and converges with epigenetic signatures of prenatal stress

Childhood maltreatment (CM) is an established major risk factor for a number of negative health outcomes later in life. While epigenetic mechanisms, such as DNA methylation (DNAm), have been proposed as a means of embedding this environmental risk factor, little is known about its timing and trajectory, especially in very young children. It is also not clear whether additional environmental adversities, often experienced by these children, converge on similar DNAm changes. Here, we calculated a cumulative adversity score, which additionally to CM includes socioeconomic status (SES), other life events, parental psychopathology and epigenetic biomarkers of prenatal smoking and alcohol consumption. We investigated the effects of CM alone as well as the adversity score on longitudinal DNAm trajectories in the Berlin Longitudinal Child Study. This is a cohort of 173 children aged 3-5 years at baseline of whom 86 were exposed to CM. These children were followed-up for 2 years with extensive psychometric and biological assessments as well as saliva collection at 5 time points providing genome-wide DNAm levels. Overall, only a few DNAm patterns were stable over this timeframe, but less than 10 DNAm regions showed significant changes. At baseline, neither CM nor the adversity score associated with DNAm changes. However, in 6 differentially methylated regions (DMRs), CM and the adversity score significantly moderated DNAm trajectories over time. A number of these DMRs have previously been associated with adverse prenatal exposures. In our study, children exposed to CM also presented with epigenetic signatures indicative of increased prenatal exposure to tobacco and alcohol, as compared to non-CM exposed children. These epigenetic signatures of prenatal exposure strongly correlate with DNAm regions associated with CM and the adversity score. Finally, weighted correlation network analysis revealed a module of CpGs exclusively associated with CM. While our study identifies DNAm loci specifically associated with CM, especially within long non-coding RNAs, the majority of associations were found with the adversity score with convergent association with indicators of adverse prenatal exposures. This study highlights the importance of mapping not only of the epigenome but also the exposome and extending the observational timeframe to well before birth.

Association of the Labor Migration of Parents With Nonsuicidal Self-injury and Suicidality Among Their Offspring in China

IMPORTANCE

The labor migration of parents in China often leaves children behind, which may be adversely associated with children's health. However, few studies have assessed the association of parental migration with nonsuicidal self-injury (NSSI) or with suicidality among their offspring.

OBJECTIVE

To examine the associations of parental labor migration with NSSI and with suicidality as well as potential differential associations by sex among offspring left behind.

DESIGN, SETTING, AND PARTICIPANTS

This nationwide cross-sectional study was conducted from February to October 2015 among individuals aged 11 to 20 years from 45 public middle and high schools across 5 provinces of China. Data analysis was performed from November 1, 2020, to March 1, 2021.

EXPOSURES

Parental labor migration, including parental migration status (yes vs no), migration pattern (father, mother, or both), and the child's age at the initial parent-child separation.

MAIN OUTCOMES AND MEASURES

Less frequent (1-4 episodes) NSSI, more frequent (≥5 episodes) NSSI, suicidal ideation, and suicide attempt in the past year were measured using validated questionnaires. Multinomial or binomial logistic regression analyses were used separately to estimate adjusted odds ratios (aORs) and 95% CIs of the associations between parental migration and NSSI, suicidal ideation, or suicide attempt. Potential covariates (demographic, family-level, and psychological characteristics) were adjusted for in 3 sequential models.

RESULTS

A total of 15 312 participants (7904 male [51.6%] and 7408 female [48.4%]) aged 11 to 20 years (mean [SD] age, 15.1 [1.8] years) were included. Of those participants, 5963 (23.3%) experienced parental migration. The 12-month prevalence of less frequent NSSI was 17.2% (2635 of 15 312), the 12-month prevalence of more frequent NSSI was 11.6% (1783 of 15 312), the 12-month prevalence of suicidal ideation was 15.2% (2335 of 15 312), and the 12-month prevalence of suicide attempt was 3.5% (535 of 15 312). Parental migration was associated with less frequent NSSI (adjusted odds ratio [aOR], 1.13; 95% CI, 1.03-1.24); no significant association of parental migration with more frequent NSSI (aOR, 1.01; 95% CI, 0.90-1.13), suicidal ideation (aOR, 1.00; 95% CI, 0.90-1.10), or suicide attempt (aOR, 1.09; 95% CI, 0.90-1.33) was identified. Compared with children whose parents did not migrate, the aOR for less frequent NSSI for participants whose father migrated was 1.18 (95% CI, 1.06-1.31), and the aOR for less frequent NSSI for participants having both parents migrate was 1.12 (95% CI, 1.01-1.28). Compared with children whose parents did not migrate, participants who experienced initial separation from 1 or both parents at preschool age had an aOR for less frequent NSSI of 1.16 (95% CI, 1.03-1.31). No sex disparities were found in these associations except for participants who experienced initial separation from 1 or both migrant parents at preschool age, for which the aOR for more frequent NSSI was higher among male (aOR, 1.27; 95% CI, 1.04-1.55) than female (aOR, 0.96; 95% CI, 0.77-1.19) participants.

CONCLUSIONS AND RELEVANCE

This cross-sectional study found that parental migration, mainly of the father or of both parents, or an initial separation of children at preschool age from 1 or both parents who migrated was associated with higher odds of experiencing 1 to 4 NSSI episodes in 1 year among offspring. Overall, the associations of parental migration with NSSI and suicidality were similar between male and female participants.

Paternal adverse childhood experiences: Associations with infant DNA methylation

Adverse childhood experiences (ACEs), or cumulative childhood stress exposures, such as abuse, neglect, and household dysfunction, predict later health problems in both the exposed individuals and their offspring. One potential explanation suggests exposure to early adversity predicts epigenetic modification, especially DNA methylation (DNAm), linked to later health. Stress experienced preconception by mothers may associate with DNAm in the next generation. We hypothesized that fathers' exposure to ACEs also associates with their offspring DNAm, which, to our knowledge, has not been previously explored. An epigenome-wide association study (EWAS) of blood DNAm (n = 45) from 3-month-old infants was regressed onto fathers' retrospective ACEs at multiple Cytosine-phosphate-Guanosine (CpG) sites to discover associations. This accounted for infants' sex, age, ethnicity, cell type proportion, and genetic variability. Higher ACE scores associated with methylation values at eight CpGs. Post-hoc analysis found no contribution of paternal education, income, marital status, and parental postpartum depression, but did with paternal smoking and BMI along with infant sleep latency. These same CpGs also contributed to the association between paternal ACEs and offspring attention problems at 3 years. Collectively, these findings suggested there were biological associations with paternal early life adversity and offspring DNAm in infancy, potentially affecting offspring later childhood outcomes.

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.

How are social determinants of health integrated into epigenetic research? A systematic review

OBJECTIVE

We systematically review the literature on social epigenetics, examining how empirical research to date has conceptualized and operationalized social determinants of health (SDOH).

METHODS

Using comprehensive search procedures, we identified studies that consider the impact of SDOH on DNA methylation (DNAm), the most common measure of epigenetic change in research on human adult populations. We analyzed the studies to determine: 1) which populations and environments have been investigated in the literature; 2) how SDOH are defined and operationalized; 3) which SDOH have been linked to DNAm; and 4) what lessons from the SDOH literature can be better integrated into future studies exploring the social determinants of health and epigenetic outcomes.

RESULTS

We identified 67 studies, with 39 to 8397 participants. The SDOH most commonly considered were early life socioeconomic exposures and early life trauma or mental health. Our review highlights four broad challenges: a) high dependence on convenience sampling, b) limited racial/ethnic, and geographic diversity in sampling frames, c) overreliance on individual sociodemographic characteristics as proxies for broader stratification processes, and d) a focus on downstream social determinants of health and individualized experiences with social stressors.

CONCLUSIONS

Future social epigenetics research should prioritize larger, more diverse and representative population-based samples and employ the SDOH framework to better inform the conceptualization of research questions and interpretation of findings. In particular, the simplified depiction of race/ethnicity, gender, and socioeconomic status as individual-level characteristics should be updated with an explicit acknowledgement that these characteristics are more accurately interpreted as cues used by society to differentiate subpopulations. Social epigenetics research can then more clearly elucidate the biological consequences of these social exposures for patterns of gene expression, subsequent disease etiology, and health inequities.

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.

HPA axis regulation and epigenetic programming of immune-related genes in chronically stressed and non-stressed mid-life women

Hypothalamic-pituitary-adrenal (HPA) axis dysregulation has been associated with altered immune function, but the underlying molecular mechanisms are unclear. Epigenetic processes, including DNA methylation, respond to the glucocorticoid end-products of the HPA axis (cortisol in humans) and could be involved in this neuroendocrine-immune crosstalk. Here we examined the extent to which variations in HPA axis regulation are associated with peripheral blood DNA (CpG) methylation changes in 57 chronically stressed caregivers and 67 control women. DNA methylation was determined with the Illumina 450k array for a panel of genes involved in HPA axis and immune function. HPA axis feedback was assessed with the low-dose dexamethasone suppression test (DST), measuring the extent to which cortisol secretion is suppressed by the synthetic glucocorticoid dexamethasone. After multiple testing correction in the entire cohort, higher post-DST cortisol, reflecting blunted HPA axis negative feedback, but not baseline waking cortisol, was associated with lower DNA methylation at eight TNF and two FKBP5 CpG sites. Caregiver group status was associated with lower methylation at two IL6 CpG sites. Since associations were most robust with TNF methylation (32% of the 450k-covered sites), we further examined functionality of this epigenetic signature in cultured peripheral blood mononuclear cells in 33 participants; intriguingly, lower TNF methylation resulted in higher ex vivo TNF mRNA following immune stimulation. Taken together, our findings link chronic stress and HPA axis regulation with epigenetic signatures at immune-related genes, thereby providing novel insights into how aberrant HPA axis function may contribute to heightened inflammation and disease risk.

Childhood Maltreatment in Bipolar Disorders

In this chapter, we will focus on childhood maltreatment and its role in the vulnerability to BD.We will review how childhood maltreatment and trauma not only predispose to the development of BD but also to a more unstable, pernicious, and severe clinical expression of the disorder. This environmental risk factor is suggested to be part of a multiple hit model of vulnerability, involving not only early stressors (prenatal and postnatal ones) but also interactions with the genetic background of individuals and with other stressors occurring later in life. We will also review how childhood maltreatment and trauma may modify the brain functioning and circuits and alter some biological pathways in BD, hence leading to psychopathology. Finally, we will briefly discuss the implications for clinical practice and treatment.

DNA methylation signatures of adolescent victimization: analysis of a longitudinal monozygotic twin sample

Accumulating evidence suggests that individuals exposed to victimization at key developmental stages may have different epigenetic fingerprints compared to those exposed to no/minimal stressful events, however results are inconclusive. This study aimed to strengthen causal inference regarding the impact of adolescent victimization on the epigenome by controlling for genetic variation, age, gender, and shared environmental exposures. We conducted longitudinal epigenome-wide association analyses (EWAS) on DNA methylation (DNAm) profiles of 118 monozygotic (MZ) twin pairs from the Environmental Risk study with and without severe adolescent victimization generated using buccal DNA collected at ages 5, 10 and 18, and the Illumina EPIC array. Additionally, we performed cross-sectional EWAS on age-18 blood and buccal DNA from the same individuals to elucidate tissue-specific signatures of severe adolescent victimization. Our analyses identified 20 suggestive differentially methylated positions (DMPs) (P < 5e-05), with altered DNAm trajectories between ages 10–18 associated with severe adolescent victimization (∆Beta range = −5.5%−5.3%). Age-18 cross-sectional analyses revealed 72 blood (∆Beta range = −2.2%−3.4%) and 42 buccal (∆Beta range = −3.6%−4.6%) suggestive severe adolescent victimization-associated DMPs, with some evidence of convergent signals between these two tissue types. Downstream regional analysis identified significant differentially methylated regions (DMRs) in LGR6 and ANK3 (Šidák P = 5e-09 and 4.07e-06), and one upstream of CCL27 (Šidák P = 2.80e-06) in age-18 blood and buccal EWAS, respectively. Our study represents the first longitudinal MZ twin analysis of DNAm and severe adolescent victimization, providing initial evidence for altered DNA methylomic signatures in individuals exposed to adolescent victimization.

Dynamic DNA methylation changes in early versus late adulthood suggest nondeterministic effects of childhood adversity: a meta-analysis

Adverse childhood experiences (ACEs) are associated with a high risk of developing chronic diseases and decreased life expectancy, but no ACE epigenetic biomarkers have been identified until now. The latter may result from the interaction of multiple factors such as age, sex, degree of adversity, and lack of transcriptional effects of DNA methylation changes. We hypothesize that DNA methylation changes are related to childhood adversity levels and current age, and these markers evolve as aging proceeds. Two Gene Expression Omnibus datasets, regarding ACE, were selected (GSE72680 and GSE70603), considering raw- and meta-data availability, including validated ACE index (Childhood Trauma Questionnaire (CTQ) score). For DNA methylation, analyzed probes were restricted to those laying within promoters and first exons, and samples were grouped by CTQ scores terciles, to compare highly (ACE) with non-abused (control) cases. Comparison of control and ACE methylome profile did not retrieve differentially methylated CpG sites (DMCs) after correcting by false discovery rate < 0.05, and this was also observed when samples were separated by sex. In contrast, grouping by decade age ranges (i.e., the 20s, 30s, 40s, and 50s) showed a progressive increase in the number of DMCs and the intensity of changes, mainly related with hypomethylation. Comparison with transcriptome data for ACE subjects in the 40s, and 50s showed a similar age-dependent effect. This study provides evidence that epigenetic markers of ACE are age-dependent, but not defined in the long term. These differences among early, middle, and late adulthood epigenomic profiles suggest a window for interventions aimed to prevent the detrimental effects of ACE.

Childhood exposure to hunger: associations with health outcomes in later life and epigenetic markers

Aim: To assess associations of early exposure to hunger with depressive symptoms and cardiovascular disease (CVD) and to investigate possible epigenetic pathways. Patients & methods: Data were based on a German population-based cohort of older adults (n = 9631). Regression models were performed for health outcomes in later life. An epigenome-wide association study for early-life exposure to hunger was performed in a subgroup (n = 2221) with whole blood DNA methylation data. Results: Childhood exposure to hunger was associated with CVD and depressive symptoms in later life. Prenatal or infant exposure was strongly associated with depressive symptoms. No CpG reached epigenome-wide significance after multiple testing correction. Conclusion: Childhood hunger is a risk factor for depressive symptoms and CVD at older age. DNA methylation could not explain this association.

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.

Genome-Wide DNA Methylation Patterns in Children Exposed to Nonpharmacologically Treated Prenatal Depressive Symptoms: Results From 2 Independent Cohorts

BACKGROUND

Maternal depressive symptoms are a common phenomenon during pregnancy and are related to negative outcomes for child development and health. Modifications in child DNA methylation are discussed as an underlying mechanism for the association between prenatal depressive symptoms and alterations in child outcomes. However, formerly reported genome-wide associations have yet to be replicated.

METHODS

In an epigenome-wide association study (EWAS), alterations of DNA methylation related to maternal prenatal depressive symptoms were investigated in buccal cell samples from 174 children (n = 52 exposed to prenatal depressive symptoms; 6-9 years old) of the German longitudinal study FRAMES-FRANCES. Whole blood samples from the independent, age-comparable ARIES subsample of the ARIES/ALSPAC study (n = 641; n = 159 exposed to prenatal depressive symptoms; 7-8 years old) were examined as a confirmation sample. Depressive symptoms were assessed with the Edinburgh Postnatal Depression Scale. DNA methylation was analyzed with the Infinium Human Methylation 450k BeadChip. Modifications in single CpGs, regions, and biological pathways were investigated. Results were adjusted for age and birth outcomes as well as postnatal and current maternal depressive symptoms. Analyses were performed for the whole sample as well as separated for sex.

RESULTS

The EWAS yielded no differentially methylated CpG or region as well as no accordance between samples withstanding correction for multiple testing. In pathway analyses, no overlapping functional domain was found to be enriched for either sample. A comparison of current and former findings suggests some overlapping methylation modifications from infancy to childhood. Results suggest that there might be sex-specific differential methylation, which should be further investigated in additional studies.

CONCLUSIONS

The current, mainly nonsignificant, results challenge the assumption of consistent modifications of DNA methylation in children exposed to prenatal depressive symptoms. Despite the relatively small sample size used in this study, this lack of significant results may reflect diverse issues of environmental epigenetic studies, which need to be addressed in future research.

The mediating role of KITLG DNA methylation in the association between childhood adversity and cortisol stress reactivity does not replicate in monocytes

Adverse childhood experiences such as maltreatment or neglect are associated with mental health problems in adulthood. Changes in the regulation of the psychological and physiological stress reaction, mediated via epigenetic modifications, are discussed as potential mechanisms. This study aimed to replicate the role of DNA methylation of the KITLG gene in mediating the association between childhood adversity and stress-induced cortisol reactivity in a sample of adults reporting childhood adversity and a matched control group (N = 60). DNA was extracted from purified CD14⁺ monocytes and genome-wide DNA methylation was assessed with the 450k BeadChip for targeted replication and exploratory analyses. As previously reported, childhood adversity was associated with significantly lower cortisol reactivity to stress. We could neither replicate the association between KITLG DNA methylation and cortisol stress reactivity nor the association with childhood adversity. Moreover, DNA methylation of the target CpG (cg27512205) was not associated with KITLG mRNA expression in monocytes. Exploratory analyses of array-wide DNA methylation patterns showed no significant results for individual sites after correction for multiple testing - neither in association with childhood trauma nor with adult cortisol stress reactivity. The analysis of differentially methylated regions (DMRs) revealed two significant regions which both mapped to non-coding genes in the association with cortisol stress reactivity. The mediating role of DNA methylation of the KITLG locus in the association between childhood adversity and cortisol stress reactivity could not be replicated in monocytes. In addition to differences in investigated tissue, reasons for non-replication might include differences between samples in age, ethnicity, trauma severity, and cortisol reactivity.

Traumatic childhood events of parents enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC)

Background: Early life experiences can have a significant impact on an individual's later behaviour, the way they view the world, their beliefs and their success at forming strong interpersonal relationships. These factors may subsequently influence the way that the individual may parent their children, which in turn may have an effect on their child's behaviour, mental health and world view. Research has linked early traumatic life experiences in the parent's childhood to disorganised attachment to their own child. In this paper we describe the data collected from parents enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) on traumatic events experienced during their childhood, so that it can act as a resource for researchers in the future when considering outcomes on the adult, their children and grandchildren. Methods: Data were collected via multiple questionnaires completed by parents enrolled into the ALSPAC study. During pregnancy and post-delivery, questionnaires were administered between 1990 and 1992 via post to the study mothers and their partners. Data were collected on life events including bereavement, sexual abuse, physical abuse, abandonment, neglect, memories of childhood and accidents. Other reports of traumatic events in childhood were reported by parents using free text. This can be made available to researchers for coding on request.

Adverse childhood experiences, DNA methylation age acceleration, and cortisol in UK children: a prospective population-based cohort study

BACKGROUND

Epigenetic mechanisms may partly explain the persistent effects of adverse childhood experiences (ACEs) on health outcomes in later life. DNA methylation can predict chronological age, and advanced methylation-predicted age beyond chronological age (DNA methylation age acceleration) is associated with ACEs, adverse mental and physical health, and elevated diurnal and baseline salivary cortisol. Childhood adversity is also associated with dysregulation of the hypothalamic-pituitary-adrenal axis, which produces the neuroendocrine hormone cortisol. It remains unknown whether these associations are specific to certain types of adversity. Herein, we investigate the associations of ACEs with DNA methylation age acceleration and plasma cortisol in the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort.

METHODS

In this study of the children in ALSPAC, we used multiple linear regression to examine associations of cumulative exposure to ACE, as well as exposure to ten individual types of ACEs, with Horvath-estimated DNA methylation age acceleration and with baseline plasma cortisol. The ten ACEs were those included in the World Health Organization's ACE International Questionnaire. Data on ACEs were prospectively collected from age 0-14 years. DNA methylation age acceleration and plasma cortisol were measured at mean 17.1 years and 15.5 years, respectively.

RESULTS

We included 974 UK children in the present study. Exposure to four or more ACEs compared to zero was associated with DNA methylation age acceleration in girls (β, 95% CI = 1.65, 0.25 to 3.04 years) but not in boys (β, 95% CI = - 0.11, - 1.48 to 1.26 years). Also, in girls, emotional abuse and physical abuse were each associated with DNA methylation age acceleration (β, 95% CI = 1.20, 0.15 to 2.26 years and β, 95% CI = 1.22, 0.06 to 2.38 years, respectively). No other ACEs were associated with accelerated DNA methylation age in either sex. Associations were also null between ACE and cortisol, and cortisol and DNA methylation age acceleration.

CONCLUSIONS

In this prospective population-based study of UK children, cumulative ACE exposure, emotional abuse, and physical abuse between age 0 and 14 years were each associated with Horvath-estimated DNA methylation age acceleration at age 17 years in girls but not in boys.

Epigenomics of being bullied: changes in DNA methylation following bullying exposure

Bullying among children is ubiquitous and associated with pervasive mental health problems. However, little is known about the biological pathways that change after exposure to bullying. Epigenome-wide changes in DNA methylation in peripheral blood were studied from pre- to post measurement of bullying exposure, in a longitudinal study of the population-based Generation R Study and Avon Longitudinal Study of Parents and Children (combined n = 1,352). Linear mixed-model results were meta-analysed to estimate how DNA methylation changed as a function of exposure to bullying. Sensitivity analyses including co-occurring child characteristics and risks were performed, as well as a Gene Ontology analysis. A candidate follow-up was employed for CpG (cytosine-phosphate-guanine) sites annotated to 5-HTT and NR3C1. One site, cg17312179, showed small changes in DNA methylation associated to bullying exposure (b = -2.67e-03, SE = 4.97e-04, p = 7.17e-08). This site is annotated to RAB14, an oncogene related to Golgi apparatus functioning, and its methylation levels decreased for exposed but increased for non-exposed. This result was consistent across sensitivity analyses. Enriched Gene Ontology pathways for differentially methylated sites included cardiac function and neurodevelopmental processes. Top CpG sites tended to have overall low levels of DNA methylation, decreasing in exposed, increasing in non-exposed individuals. There were no gene-wide corrected findings for 5-HTT and NR3C1. This is the first study to identify changes in DNA methylation associated with bullying exposure at the epigenome-wide significance level. Consistent with other population-based studies, we do not find evidence for strong associations between bullying exposure and DNA methylation.

Large epigenome-wide association study of childhood ADHD identifies peripheral DNA methylation associated with disease and polygenic risk burden

Epigenetic variation in peripheral tissues is being widely studied as a molecular biomarker of complex disease and disease-related exposures. To date, few studies have examined differences in DNA methylation associated with attention-deficit hyperactivity disorder (ADHD). In this study, we profiled genetic and methylomic variation across the genome in saliva samples from children (age 7-12 years) with clinically established ADHD (N = 391) and nonpsychiatric controls (N = 213). We tested for differentially methylated positions (DMPs) associated with both ADHD diagnosis and ADHD polygenic risk score, by using linear regression models including smoking, medication effects, and other potential confounders in our statistical models. Our results support previously reported associations between ADHD and DNA methylation levels at sites annotated to VIPR2, and identify several novel disease-associated DMPs (p < 1e-5), although none of them were genome-wide significant. The two top-ranked, ADHD-associated DMPs (cg17478313 annotated to SLC7A8 and cg21609804 annotated to MARK2) are also significantly associated with nearby SNPs (p = 1.2e-46 and p = 2.07e-59), providing evidence that disease-associated DMPs are under genetic control. We also report a genome-wide significant association between ADHD polygenic risk and variable DNA methylation at a site annotated to the promoter of GART and SON (p = 6.71E-8). Finally, we show that ADHD-associated SNPs colocalize with SNPs associated with methylation levels in saliva. This is the first large-scale study of DNA methylation in children with ADHD. Our results represent novel epigenetic biomarkers for ADHD that may be useful for patient stratification, reinforce the importance of genetic effects on DNA methylation, and provide plausible molecular mechanisms for ADHD risk variants.