March 28, 2011
Ask a typical student who is studying epidemiology what she or he is learning, and the overwhelming answer will refer to a set of methods useful for analyzing the distribution and determinants of population patterns of health. Ask the same student to name the epidemiologic theories of disease distribution that give rise to the hypotheses being tested in epidemiologic research, and the likely answer will be an awkward silence. And ask the student to recount what she or he has been taught about the history of epidemiology, and the answer almost always will have something to do with John Snow removing the handle of the Broad Street Pump in 1854 to stop a cholera epidemic in London.
It is this limited understanding of what is actually the long, rich role – and contentious history – of epidemiologic theory in shaping knowledge about the causes of the societal distributions of health and disease that Nancy Krieger, HSPH professor of society, human development, and health, challenges in her new book Epidemiology and The People’s Health: Theory and Context, being released in April 2011 from Oxford University Press. Krieger is also the co-director of the HSPH Interdisciplinary Concentration on Women, Gender and Health and co-founder and Chair of the Spirit of 1848 Caucus of the American Public Health Association, which focuses on links between social justice and public health.
In the eight-chapter, 400-page book Krieger traces and analyzes the history and contours of epidemiologic theories from ancient societies on through the development of – and debates within – contemporary epidemiology worldwide. “This book reflects work I’ve been engaged in and thinking about for many years. It presents what I wish I’d been taught, when I was studying to become an epidemiologist, about the theories and history of my field,” Krieger said in an interview in her office at the School. It also reflects what she currently teaches, in a course required of all doctoral students in her department, on “History, Politics, and Public Health: Theories of Disease Distribution and Social Inequalities in Health” (SHH215).
The book’s central argument is that epidemiologic theory – itself influenced by the societal and ecologic context in which it is conceived – has long shaped epidemiologic practice, knowledge, and the politics of public health. Examples discussed range from critical analysis of ancient classical texts of Greek Hippocratic humoral theory and Chinese medicine to current oral traditions of the Kallawaya in the Andes and the Ogori in Nigeria, on through contrasts between contemporary dominant biomedical and lifestyle theories of disease distribution and the different schools of social epidemiologic theories: sociopolitical, psychosocial and, most recently, ecosocial.
This last theory, which Krieger first proposed in 1994, systematically links social and biological processes across levels and diverse spatiotemporal scales, paying heed to lifecourse and historical generation, to political economy, and to interrelationships between – and accountability for – diverse forms of social inequality. A central emphasis of ecosocial theory is on “embodiment,” referring to how people literally incorporate, biologically, in societal and ecologic context, the material and social world in which we live, thereby creating population patterns of health, disease, and well-being. Also important are the cumulative interplay, at multiple levels and over time, of exposure, susceptibility and resistance, as well as accountability and agency: both for social disparities in health and research to explain these inequities.
To bring home the real-life consequences of epidemiologic theory, in the last chapter of the book Krieger offers four contemporary case studies of how people’s health has been harmed – or helped – depending on epidemiologic theory employed. For “harm,” case examples are: (1) hormone therapy, cardiovascular disease, and breast cancer, with iatrogenic disease resulting from biomedical disregard for social determinants of health; (2) peptic ulcers, H. pylori, and allergies, contrasting psychosocial and biomedical extremes; (3) diabetes and Indigenous health, tracing theorizing from “thrifty genes” and racialized disease to reckoning with the transgenerational biological embodiment of social and ecological injustice; and (4) the impact of curtailing and depoliticizing relevant timeframes for analyzing temporal trends in health inequities. For “help,” they are: (a) improving public health surveillance systems; (b) exposing discrimination as a determinant of health inequities; and (c) new national policies and global recommendations to promote health equity. Looking ahead, the book argues that the science of epidemiology can be improved by consciously embracing, developing, and debating epidemiologic theories of disease distribution.
Krieger launched the book with a lecture and book signing March 9 at the Harvard Center for Population and Development Studies.