Embarking on a Science Vision for Health Disparities Research

Thirty years ago (1985), the landmark Report of the Secretary’s Task Force on Black and Minority Health (also known as the Heckler Report) was released to demonstrate the excess deaths among racial and ethnic minorities that existed in the United States.¹ The Heckler Report marked the first convening of a group of health experts by the US government to conduct a comprehensive study of racial and ethnic minority health and engage the nation in deliberate, thoughtful discussions about the poor health status and needs of racial and ethnic minority communities. In the words of Secretary Margaret Heckler, the visionary force behind the report, health disparities were “an affront both to our ideals and to the ongoing genius of American medicine.”¹ This report paved the way for progress and unparalleled opportunities to identify solutions to the problem of disparities in health among racial and ethnic minority groups and other disadvantaged populations that had long plagued the country. The legitimization of health disparities as an area of research and remediation was set in motion by the Heckler Report.^2,3 Communities became engaged in a national dialogue to address health disparities. Federal agencies established offices dedicated to addressing racial and ethnic minority health and health equity initiatives. The National Institutes of Health (NIH) established an Office on Minority Programs, which became the Office of Research on Minority Health and later the National Center on Minority Health and Health Disparities. Today, it is the National Institute on Minority Health and Health Disparities (NIMHD), and it remains committed to ensuring that research addressing health disparities continues to build on scientific breakthroughs and technological advances.

Despite these positive developments, the failures to address health disparities before and, to a lesser extent, since the Heckler Report, have been at considerable costs to society. Within the research community, the traditional focus on biomedical factors and the neglect of investments in the social and environmental sciences has slowed progress in closing the health disparities gap. Currently there is considerable evidence on how to protect the health of populations by stimulating healthier behaviors, improving the conditions in which people live, work, and play, and implementing targeted interventions to prevent adverse health outcomes. In fact, never before has there been such a wealth of information on the influence of biological and environmental contributions on health. As the understanding of population health advances, the integration of the social and biological sciences to inform interventions has become more integral to advancing health disparities research. New questions are now emerging that ask: “What are the critical and sensitive periods in the human life cycle that appear most promising as targets for prevention, early detection, and intervention?” “How can we buffer the harmful effects of adversity and provide children and adolescents with the protections necessary for optimal executive functioning and emotion-processing during sensitive periods of neural and biological development?” “How can we best leverage these scientific advances to inform policies and practice?”

MATURING THE SCIENCE OF HEALTH DISPARITIES RESEARCH

The NIMHD is embarking on a new science vision for research on minority health and health disparities at the NIH. The idea of health disparities as a scientific discipline has launched a new and exciting research agenda that aligns new theories, models, and measures with old paradigms. Health disparities research has evolved to include research addressing statistical differences in health and health outcomes closely linked with social, economic, and environmental disadvantage. These differences are associated with higher incidence and prevalence, earlier onset, faster progression, and poorer outcomes of disease and conditions. With methodological advances and the greater availability of data, there has been a burst of scientific activity exploring how social environments and lived experiences impact health across the life course. The fundamental health disparities research questions have largely attempted to explore the general case for “why” disparities occur and “what” causes the disparities. A key response to both of these questions is to deepen our understanding of the pathways and mechanisms underlying the biological and nonbiological determinants of health disparities.

FUNDAMENTAL ISSUES FOR CONSIDERATION

Health disparities research at the NIH is a broad, multifaceted field informed by basic, applied, clinical, behavioral, and social sciences. These fields contribute to our understanding of the etiology of the disparities and the development and implementation of methods to identify, prevent, and mitigate such disparities, with the eventual goal of improving population health. Extensive evidence from developmental biology, neuroscience, and environmental epigenetics about how personal experiences, environmental exposures, and biology are interrelated demonstrates the complexity of interactive factors and their impact on health. Scientific advances shed new light on the mechanisms underlying well-established associations between social disadvantage, adversity, and suboptimal life course trajectories faced by health disparity populations. These advances also provide promising opportunities to establish new knowledge for developing more effective interventions. To mature the science of eliminating health disparities, there are a number of fundamental issues and research questions to be answered. What do these scientific advances tell us? What are the implications for health disparities research in the next decade?

Stress Perceptions and Reaction to Adversity

Converging evidence on the interplay of chronic stress, resilience and health outcomes is of increasing interest for understanding the role of social disadvantage in health disparities research. For example, research on the biology of stress illustrates how physiological reactions that occur in response to a perceived threat, such as increased heart rate and blood pressure, are able to trigger the fight-or-flight response of the sympathetic nervous system. However, excessive or prolonged activation of the stress response systems can lead to long-term disruptions in brain architecture, immune status, cardiovascular function, and endocrine function. Science tells us that adverse life events in childhood, particularly if they occur repeatedly and chronically, are associated with alterations in stress reactivity during adulthood which can include exaggerated sensitivities.⁴ The research literature highlights the huge variability in perceptions of stress and reaction to adversity.^5–7 In fact, observations spanning several decades have convincingly illustrated the negative influence of various exposures to stress and adversity in early life on learning, behavior, cognitive function, and health outcomes.⁸ Outcomes of early adversity and associated poverty may vary with the nature of the stress and the mechanisms are likely to vary with age. There are some children who thrive and emerge as resilient and strong, surviving adversity against all odds.⁷ In cross sectional studies of adult and childhood vulnerability to chronic stress and adversity, the critical missing piece of evidence is longitudinal data that includes adolescents.

Neural Basis of Behavior as a Health Determinant

Advances in neuroscience and behavior indicate that human performance in childhood, adolescence, and through adulthood reflects the neural circuits that are laid down by early social and environmental experience. Major experiences in childhood can affect adult brain structure. Although learning and optimal brain development occurs and is possible throughout life, there is no doubt that children who have an early start at learning fare better.⁹ This research, therefore, suggests that greater reductions in disparities in health and development are likely to result from more effective strategies for protecting developing neural and biological systems in children and young adults living in adverse conditions. This approach would call for providing information for parents and enrichment of caregivers. There is an equal need to optimize the experience of these adult caregivers, especially if they themselves have been exposed to adverse or suboptimal conditions that may not have been conducive to their health and well-being. The research also provides evidence that some basic parenting education, along with stimulating learning experiences and health promoting environments can lead to a healthy developmental trajectory. But in cases of significant adversity, there may be a resulting developmental impediment that overwhelms the normal developmental trajectory and limits the ability of these children to benefit from learning opportunities. Social disadvantage is not a linear, isolated experience, but an accumulation of multiple lived and perceived experiences, across time and developmental phases.

A New Paradigm for Health Disparities Research

In conclusion, the vision for the science of health disparities requires an appreciation of the value of various disciplines. It also requires an understanding of how epigenetic changes are manifested. What and how do environmental changes bring about epigenetic changes—in biological systems to influence disease processes and in neural systems to influence behaviors and behavior change? How are the adverse circumstances of children biologically embedded into the molecular and epigenetic systems to determine their expressions of vulnerability or resilience? Will the epigenetic effects of neglect, abuse and social inequality all be the same? Will effects vary according to the age when they are experienced? Will the effects vary according to the stage of brain development and will they occur even in later adult life?

The enthusiasm generated as a result of scientific breakthroughs is irrelevant if it is not translated into practice or policy for improved population health. To the extent that these assessments and research questions can be incorporated into the science vision for health disparities research, we will continue to learn more about the complexities of health disparities. The research community, as well as the US population at large, will benefit from new and improved prevention interventions and enhanced public health strategies to promote health and wellness. However, the challenges and opportunities raised in this issue will require researchers to reach beyond the boundaries of their respective fields to harness the potential that this newly integrated science vision provides for improving the public’s health.