CHAPTER 2 Aging, Health, and the Environment: an Ecological Model
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CHAPTER 2 Aging, Health, and the Environment: An Ecological Model Marlon Maus and William A. Satariano ABSTRACT Research into the epidemiology of aging is an increasingly complex discipline in the face of a growing older population and the exponential growth of information in the field. To study, measure, describe, and test the multiple factors and hypotheses that make up the study of aging in the 21st century requires a conceptual framework that takes into account these numerous components. The ecological model is exceptionally well suited to consider the various determinants of health at multiple levels. In the framework used in this text, the model is essentially integrated into a life course perspective, as it is now generally accepted that factors occurring early in life have an important effect on how people age. The concept of “place,” which suggests that where people age, including the built environment, is an essential contextual element that must also be incorporated when exploring the field of aging. KEYWORDS ecological model epidemiology of aging aging research life course perspective resilience Image: Hands © Shutterstock, Inc./Dewald Kirsten; Buildings © Shutterstock, Inc./Bariskina 23 9781284069389_CH02_Pass03.indd 23 18/01/17 8:34 PM 24 Chapter 2 Aging, Health, and the Environment: An Ecological Model and longevity by considering the determinants ▸ Introduction: Why Use of health at various levels from the individual an Ecological Model and the interpersonal to the community and policy levels over the life course. The original and a Life Course IOM model is adapted here to illustrate the determinants and ecological nature of health Perspective in the across the life course and includes elements such as biological factors, personal relation- Epidemiology of Aging? ships, community contexts, and wider societal factors, as well as traditional demographics Epidemiology has been defined as the study such as place, gender, race, ethnicity, and and analysis of the patterns, causes, and effects socioeconomic status (Committee on Assur- of health and disease conditions in defined ing the Health of the Public in the 21st Cen- populations. It is one of the main pillars of public health, as it helps design the studies tury, 2002). In addition, we incorporate more and interventions that support evidence-based recent work that has been done to enhance our practices and that shape the policy decisions understanding of “life course” and “place”— that are ultimately responsible for how con- two key components of the ecological model. temporary health care is typically provided. We advocate that an ecological framework life course perspective When epidemiology targets the fast-growing with a is the ideal aging population, it must address various top- lens that can treat the interaction between fac- ics that are related to health, functioning, and tors at different levels with equal importance longevity. Some of the leading areas of research to the factors within a single level (Violence include the effects of age and aging on survival Prevention Alliance, 2016). and mortality and the causes of death; physical Many appeals have been made to move functioning, disability, and activities of every- modern epidemiology from the study of prox- day life; cognitive functioning; depression and imate, individual-level risks to the social‒ other psychosocial disorders; falls and injuries; ecological perspective that would allow frailty and geriatric syndromes; and, of course, greater insights into the complex social and disease and comorbidities. environmental systems that are the context for Ample evidence shows that no single health and disease; thinking about population factor can explain why some people—and, health; and using life course models of dis- indeed, some populations—are able to do well ease risk acquisition (McMichael, 1999). This as they age, whereas others do not (Violence approach is particularly important in view of Prevention Alliance, 2016). Rather, it is the how the growing world population and eco- interactions among the many factors, at many nomic activity are affecting the environment levels and over the life course, that determine and its relationship with the health of an aging the health outcomes we are considering. population. The Institute of Medicine (IOM) has The ecological approach is contextual in defined the ecological model as “a model of nature and requires an awareness of the mul- health that emphasizes the linkages and rela- tifaceted nature of the conditions and moti- tionships among multiple factors (or determi- vations for the expression of behavior across nants) affecting health” (Gebbie, Rosenstock, environmental conditions (Kelly, 2006). The & Hernandez, 2003, p. 1). In the first edition ecological approach both to research and of this text, the ecological model was used as practice has been described as having four a conceptual framework that focuses on the constituent facets: (1) It takes into account age-associated patterns of health, functioning, the interrelationships of persons and settings, 9781284069389_CH02_Pass03.indd 24 18/01/17 8:34 PM The Ecological Model 25 (2) It is based on ecological knowledge, (3) It mentioned in this text’s title becomes indis- uses a collaborative style, and (4) It is based on pensable. The study and research of health in social processes (Kelly, 2006). the 21st century must take place in a vastly The ecological model provides a sense more interconnected world. In such a world of “the big picture” by enabling epidemiolog- of networks, mathematical models show that ical research in aging to combine knowledge even though most nodes are not neighbors of from a wide range of scientific disciplines, one another, most nodes can be reached from including the biologic, behavioral, social, and every other node by a small number of hops environmental health sciences. Whereas the or steps (Telesford, Joyce, Hayasaka, Burdette, ecological model focuses on a static picture of & Laurienti, 2011). These nodes, representing an individual or a population, the addition of individuals, their peer groups, families, com- a life course perspective provides a temporal munities, schools, and workplaces, are embed- progression that connects the various elements ded in the broad economic, cultural, social, of an ecological model to the health outcomes and physical environmental conditions at the at the various stages of life. As an example, local, national, and global levels, and are now studies show that in utero exposure to the intimately interconnected by technology, such 1918 flu pandemic had long-lasting negative as social media or ubiquitous transportation. health consequences much later in life, includ- Moreover, all of these interactions are taking ing a higher probability of developing coro- place in the context of potentially cataclysmic nary heart disease, diabetes, kidney disorders, events that know no geographic borders, such or generally poor health (Garthwaite, 2008). as climate change and massive population Other evidence shows that a cohort with fetal migrations resulting from political, economic, exposure to a pandemic performs significantly and environmental events. worse in terms of educational attainment and has a lower chance of marriage than its con- temporaries without such exposure (Neelsen & Stratmann, 2012). This concept is explored ▸ The Ecological Model in greater detail in the chapter on early-life In this section, we present an ecological model predictors of late-life health. with a life course perspective that serves as It is not just the events very early in life the framework for the other chapters in this that manifest themselves as changes in health text, and is intended to be used as a guide for late in life. In fact, events occurring at every what is being done and an agenda for what stage in life affect subsequent stages of life. The should be done in the field of the epidemiol- cumulative progression that occurs over the ogy of aging. By looking at key topic areas in life course can include both events with nega- this field as outcomes rather than as distinct tive effects and events with positive effects. In areas of research, we suggest that the following addition, these events can, and do, take place areas are intimately interrelated: survival and at every level of the ecological model through- mortality; physical functioning and activities out the life course. Community and societal of everyday life; crashes; cognitive function- events, such as an economic recession or a ing; depression; falls and injuries; and disease war, may have as powerful effects on health and comorbidities. In addition, we attempt to outcomes later in life as those occurring at the integrate the conclusions from these discus- individual biological level. sions into a blueprint for future directions that Finally, for a universal and comprehen- may help researchers, students, and practi- sive understanding of the epidemiology tioners plan for potential activities and allocate of aging, the “global perspective” approach resources. 9781284069389_CH02_Pass03.indd 25 18/01/17 8:34 PM 26 Chapter 2 Aging, Health, and the Environment: An Ecological Model An Overview that shape patterns of health and of disease as well as our responses to them over the entire As the fraction of older adults in the world life cycle (Fielding, Teutsch, & Breslow, 2010). population continues to increase, the need to Some of the determinants of health in the fulfill the World Health Organization’s (WHO, ecological model are listed in TABLE 2-1. For 1946) definition of health—“a state of complete communities to be healthy, meaning that they physical, mental, and social well-being and not merely the absence of disease or infirmity”— have the capacity to allow each individual to be takes on a new level of urgency. The medical healthy, they must address all of these factors. model that has dominated the U.S. healthcare The idea of a social ecological perspective system since the 19th century and for much has its origins in the writings of Kurt Lewin, of the 20th century is an untenable approach starting in the 1930s.