Epigenetic signals of how social disadvantage “gets under the skin”: a challenge to the public health community

Epigenetic mechanisms linking early-life adversities and mental health

Early-life adversities, whether prenatal or postnatal exposure, have been linked to adverse mental health outcomes later in life increasing the risk of several psychiatric disorders. Research on its neurobiological consequences demonstrated an association between exposure to adversities and persistent alterations in the structure, function, and connectivity of the brain. Consistent evidence supports the idea that regulation of gene expression through epigenetic mechanisms are involved in embedding the impact of early-life experiences in the genome and mediate between social environments and later behavioral phenotypes. In addition, studies from rodent models and humans suggest that these experiences and the acquired risk factors can be transmitted through epigenetic mechanisms to offspring and the following generations potentially contributing to a cycle of disease or disease risk. However, one of the important aspects of epigenetic mechanisms, unlike genetic sequences that are fixed and unchangeable, is that although the epigenetic markings are long-lasting, they are nevertheless potentially reversible. In this review, we summarize our current understanding of the epigenetic mechanisms involved in the mental health consequences derived from early-life exposure to malnutrition, maltreatment and poverty, adversities with huge and pervasive impact on mental health. We also discuss the evidence about transgenerational epigenetic inheritance in mammals and experimental data suggesting that suitable social and pharmacological interventions could reverse adverse epigenetic modifications induced by early-life negative social experiences. In this regard, these studies must be accompanied by efforts to determine the causes that promote these adversities and that result in health inequity in the population.

The use of race terms in epigenetics research: considerations moving forward

The field of environmental epigenetics is uniquely suited to investigate biologic mechanisms that have the potential to link stressors to health disparities. However, it is common practice in basic epigenetic research to treat race as a covariable in large data analyses in a way that can perpetuate harmful biases without providing any biologic insight. In this article, we i) propose that epigenetic researchers open a dialogue about how and why race is employed in study designs and think critically about how this might perpetuate harmful biases; ii) call for interdisciplinary conversation and collaboration between epigeneticists and social scientists to promote the collection of more detailed social metrics, particularly institutional and structural metrics such as levels of discrimination that could improve our understanding of individual health outcomes; iii) encourage the development of standards and practices that promote full transparency about data collection methods, particularly with regard to race; and iv) encourage the field of epigenetics to continue to investigate how social structures contribute to biological health disparities, with a particular focus on the influence that structural racism may have in driving these health disparities.

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.

Pregnancy and Infant Development (PRIDE)-a preliminary observational study of maternal adversity and infant development

Background

Children from socioeconomically disadvantaged families have a markedly elevated risk for impaired cognitive and social-emotional development. Children in poverty experience have a high risk for developmental delays. Poverty engenders disproportionate exposure to psychological adversity which may contribute to impaired offspring development; however the effect may be mitigated by social support and other aspects of resilience. Our objective was to determine the association between maternal stress, adversity and social support and early infant neurobehavior and child behavior at two and three years.

Methods

We conducted a longitudinal mother-infant cohort study nested within a regional home visiting program in Cincinnati, Ohio. Four home study visits were completed to collect measures of maternal stress, adversity and social support and infant and child behavior. A measure of infant neurobehavior (‘high-arousal’ infant) was derived from the NICU Network Neurobehavioral Scale (NNNS) at 1 month and externalizing and internalizing symptoms were measured by the Child Behavior Checklist (CBCL) at 24 and 36 months. Linear and logistic regression identified associations between maternal risk/protective factors and infant and child behavioral measures. We used stratification and multiplicative interaction terms to examine potential interactions.

Results

We enrolled n = 55 pregnant mothers and follow 53 mother–offspring dyads at 1 month, 40 dyads at 24 months and 27 dyads at 36 months. Maternal adversity and protective factors were not associated with neurobehavior at one month. However, maternal depression and measures of distress in pregnancy were significantly associated with internalizing and externalizing symptoms at 24 and 36 months.

Conclusions

This pilot study established the feasibility of conducting longitudinal research within a community intervention program. In addition, although there were no statistically significant associations between maternal psychosocial factors in pregnancy and infant neurobehavior, there were several associations at 24 months, primarily internalizing symptoms, which persisted through 36 months. Future work will replicate findings within a larger study as well as explore mediators and modifiers of these associations.

Systemic racism can get under our skin and into our genes

Special Issue - Race reconciled II: Interpreting and communicating biological variation and race in 2021 Many sociocultural factors, like poverty and trauma, or homelessness versus a safe neighborhood, can get "under our skin" and affect our lives. These factors may also get "into our genes" through epigenetic changes that influence how genes are expressed. Changes in gene expression can further influence how we respond to sociocultural factors and how those factors impact our physical and mental health, creating a feedback loop between our sociocultural environment and our genome.

From social determinants to social epigenetics: Health geographies of chronic disease

Social epigenetics explores relationships between social factors and health inequities embodied at the molecular level. Through modulating gene expression, epigenetic changes resulting from human-environment interactions may play a role in shaping health trajectories. This paper applies a health geography lens to explore the potential and support for conducting social epigenetic studies of chronic diseases with complex and dynamic etiologies. In so doing, we argue that social epigenetics presents a novel space for investigations of health and disease that is transdisciplinary and builds upon new understandings of bodies and place-based experiences. Given gender disparities in chronic diseases, we adopt a feminist perspective that cogitates the transactive relationships between gender and health/ill-health as mediated by biosocial processes at a variety of scales. Looking forward to the practical undertaking of social epigenetic studies, we assess existing theoretical and methodological support as well as insights to be gained. Reflecting upon the central tenets of health geography, we propose a unique positionality for health geographers to drive this field forward.

The National Institute on Minority Health and Health Disparities Research Framework

We introduce the National Institute on Minority Health and Health Disparities (NIMHD) research framework, a product that emerged from the NIMHD science visioning process. The NIMHD research framework is a multilevel, multidomain model that depicts a wide array of health determinants relevant to understanding and addressing minority health and health disparities and promoting health equity. We describe the conceptual underpinnings of the framework and define its components. We also describe how the framework can be used to assess minority health and health disparities research as well as priorities for the future. Finally, we describe how fiscal year 2015 research project grants funded by NIMHD map onto the framework, and we identify gaps and opportunities for future minority health and health disparities research.

Differential vulnerability and susceptibility: how to make use of recent development in our understanding of mediation and interaction to tackle health inequalities

This paper discusses the concepts of vulnerability and susceptibility and their relevance for understanding and tackling health inequalities. Tackling socioeconomic inequalities in health is based on an understanding of how an individual's social position influences disease risk. Conceptually, there are two possible mechanisms (not mutually exclusive): there is either some cause(s) of disease that are unevenly distributed across socioeconomic groups (differential exposure) or the effect of some cause(s) of disease differs across groups (differential effect). Since differential vulnerability and susceptibility are often used to denote the latter, we discuss these concepts and their current use and suggest an epidemiologically relevant distinction. The effect of social position can thus be mediated by causes that are unevenly distributed across social groups and/or interact with social position. Recent improvements in the methodology to estimate mediation and interaction have made it possible to calculate measures of relevance for setting targets and priorities in policy for health equity which include both mechanisms, i.e. equalize exposure or equalize effects. We finally discuss the importance of differential susceptibility and vulnerability for the choice of preventive strategies, including approaches that target high-risk individuals, whole populations and vulnerable groups.

New research directions on disparities in obesity and type 2 diabetes

Obesity and type 2 diabetes disproportionately impact U.S. racial and ethnic minority communities and low-income populations. Improvements in implementing efficacious interventions to reduce the incidence of type 2 diabetes are underway (i.e., the National Diabetes Prevention Program), but challenges in effectively scaling-up successful interventions and reaching at-risk populations remain. In October 2017, the National Institutes of Health convened a workshop to understand how to (1) address socioeconomic and other environmental conditions that perpetuate disparities in the burden of obesity and type 2 diabetes; (2) design effective prevention and treatment strategies that are accessible, feasible, culturally relevant, and acceptable to diverse population groups; and (3) achieve sustainable health improvement approaches in communities with the greatest burden of these diseases. Common features of guiding frameworks to understand and address disparities and promote health equity were described. Promising research directions were identified in numerous areas, including study design, methodology, and core metrics; program implementation and scalability; the integration of medical care and social services; strategies to enhance patient empowerment; and understanding and addressing the impact of psychosocial stress on disease onset and progression in addition to factors that support resiliency and health.

Epigenetics, ethics, law and society: A multidisciplinary review of descriptive, instrumental, dialectical and reflexive analyses

Epigenetics, defined as 'the study of mitotically and/or meiotically heritable changes in gene function that cannot be explained by changes in DNA sequence', has emerged as a promissory yet controversial field of scientific inquiry over the past decade. Scholars from many disciplines have formulated both optimistic and cautionary claims regarding its potential normative implications. This article provides a comprehensive review of the nascent literature at the crossroads of epigenetics, ethics, law and society. It describes nine emerging areas of discussion, relating to (1) the impact of epigenetics on the nature versus nurture dualism, (2) the potential resulting biologization of the social, (3) the meaning of epigenetics for public health, its potential influence on (4) reproduction and parenting, (5) political theory and (6) legal proceedings, and concerns regarding (7) stigmatization and discrimination, (8) privacy protection and (9) knowledge translation. While there is some degree of similarity between the nature and content of these areas and the abundant literature on ethical, legal and social issues in genetics, the potential implications of epigenetics ought not be conflated with the latter. Critical studies on epigenetics are emerging within a separate space of bioethical and biopolitical investigations and claims, with scholars from various epistemological standpoints utilizing distinct yet complementary analytical approaches.

Lung Cancer Screening and Epigenetics in African Americans: The Role of the Socioecological Framework

Lung cancer is the leading cause of cancer morbidity and mortality in the U.S. and racial/ethnic minorities carry the greatest burden of lung cancer disparities with African Americans (AAs) impacted disproportionately. Inequities in lung cancer health disparities are often associated with multiple bio-behavioral and socio-cultural factors among racial/ethnic minorities. Epigenetic research has advanced the understanding of the intersectionality between biological and socio-cultural factors in lung cancer disparities among AAs. However, gaps exist in the engagement of diverse populations in epigenetic lung cancer research, which poses a challenge in ensuring the generalizability and implementation of epigenetic research in populations that carry an unequal cancer burden. Grounding epigenetic lung cancer research within a socio-ecological framework may prove promising in implementing a multi-level approach to community engagement, screening, navigation, and research participation among AAs. The University of Illinois Cancer Center (UI Cancer Center) is employing an evidence–based (EB) model of community/patient engagement utilizing the socio-ecological model (SEM) to develop a culturally sensitive epigenetic lung cancer research program that addresses multiple factors that impact lung cancer outcomes in AAs. By implementing epigenetic research within a group of Federally Qualified Health Centers (FQHCs) guided by the SEM, the UI Cancer Center is proposing a new pathway in mitigating lung cancer disparities in underserved communities. At the individual level, the framework examines tobacco use among patients at FQHCs (the organizational level) and also tailors epigenetic research to explore innovative biomarkers in high risk populations. Interpersonal interventions use Patient Navigators to support navigation to EB tobacco cessation resources and lung cancer screening. Community level support within the SEM is developed by ongoing partnerships with local and national partners such as the American Lung Association (ALA) and the American Cancer Society (ACS). Lastly, at the policy level, the UI Cancer Center acknowledges the role of policy implications in lung cancer screening and advocates for policies and screening recommendations that examine the current guidelines from the United States Preventive Services Task Force (USPTF).

Explaining the Relationship Between Minority Group Status and Health Disparities: A Review of Selected Concepts

Purpose: There is growing concern that value-based payment for health care may disadvantage health care organizations that serve populations with social risk. In the broader investigation of social risk factors, including income, education, neighborhood deprivation, and other risks, the focus on race and ethnicity as a risk factor for disparities in health and health care has diminished. Understanding the independent contribution of minority group status is critical to this discussion. This narrative review discusses four concepts—minority stress, resilience, epigenetics, and life course—that may help explain the contribution of minority group status and its association with health disparities.

Methods: We briefly describe each concept and the supporting evidence.

Results: Our results indicate that all four concepts have potential relevance for understanding and addressing health disparities. The life course perspective emphasizes the importance of understanding explanatory mechanisms and factors that contribute to health—including biological, physical, and social factors—over a person's life span. Both minority stress and resilience may influence health in either a negative or positive manner that potentially underlies health changes. Exposure to these factors and others may interact with and modify epigenetic regulation—biological processes that impact how our genes are expressed. This may increase the risk of disease and negative health outcomes, particularly among groups that may be at disproportionate risk because of social circumstances and environmental exposure over the life course.

Conclusion: Despite these concepts' relevance, more research is needed to assess how they may explain the relationship between minority status and disparities in health. Such evidence is needed to focus interventions and to inform the design of delivery and payment models that can spur actions to reduce disparities.