By Lisa Stein
 Assistant professor Emma Adam and doctoral student Leah Doane study cortisol levels indicating stress in adolescents. Photo by Treavor Doherty   Professor P. Lindsay Chase-Lansdale and other SESP faculty attend a C2S colloquium on the link between stress and illness. Photos by Andrew Campbell |
 |
Just what makes a person, or an entire population, healthier or sicker than another has intrigued and puzzled researchers for a long time. In the United States, the data documenting health disparities between people of different races and socioeconomic levels paint a stark picture. A poor person is up to four times more likely than a middle-class or wealthy person to contract any major disease. A member of a racial or ethnic minority group carries a much higher risk of contracting diseases such as diabetes, cardiovascular disease and cancer. Scientists still struggle with pinning down underlying causes and finding ways of making things better. Part of the problem lies in the mind-boggling complexity of factors contributing to health. We already know the huge roles that genetics and lifestyle choices play in achieving and maintaining health. But today scientists are placing increasing importance on additional factors such as social inequality, stress, and the quality of personal relationships and education. They recognize this connection with education: More educated people are generally healthier than less educated people, and healthier people are more educated than less healthy people. "If we really want to understand the causes and consequences of disparities in our society, we need to look at people's biological responses to social environments," asserts P. Lindsay Chase-Lansdale, professor of human development and social policy in the School of Education and Social Policy (SESP) and faculty fellow at the Institute for Policy Research (IPR). In other words, to what degree does someone's neighborhood, quality of marriage, stress levels and exposure to racial discrimination affect his or her health? How do those findings play out at the population level? To help answer those questions, Chase-Lansdale and colleagues at IPR decided in 2004 to launch Cells to Society (C2S): The Center on Social Disparities and Health. With Chase-Lansdale at the helm, C2S brings together 16 faculty members from the social, behavioral, biomedical and life sciences at Northwestern. These researchers are united by their interest in exploring innovative approaches to understanding how social experiences affect the body's functioning. Their long-term goal is nothing less than reducing health disparities through new research findings that improve public policy and practice. According to Chase-Lansdale, the time is ripe for C2S. "Studies have shown that the United States is more unequal today than at any time since the 1920s. People's health both leads to these disparities and is a consequence of them. If you're in poor health, you're less likely to finish school and get a job, and if you're a perfectly healthy person and you're being treated poorly and experiencing stress related to poverty, you're less likely to be healthy in the long term." Interdisciplinary attack Chase-Lansdale considers the center's biggest strength to be its broad interdisciplinary approach, which promotes advances. "The social scientists tackle the social side of issues, and the biomedical scientists are experts in the in-depth aspects of bio-assays and research, and together they enhance each other's work." |
"C2S provides an incredible avenue to just think bigger and broader," agrees Jennifer Richeson, associate professor of psychology in the Weinberg College of Arts and Sciences. Richeson studies how interracial interactions affect both majority and minority groups. She recently completed a groundbreaking study focusing on interactions at Dartmouth College, using magnetic resonance imaging (MRI) to assess what happens in the brains of white students when they are shown pictures of African Americans. Surprisingly, the MRI scans revealed clear changes in the students' brain activity, suggesting that they may have been controlling their own thoughts when looking at the pictures.
"Any time you're monitoring your thoughts you're using a cognitive function that is really demanding on cognitive resources," Richeson reports. "The goal is to figure out what people are doing during interracial interactions. What does it mean for them? Does it mean that African Americans and their white counterparts will be exhausted, cognitively or emotionally, from interactions?" Richeson speculates that research completed at C2S could lead to policy changes on college campuses to ameliorate the effects of stressful interactions.
Innovative techniques
Using and developing new techniques to measure people's response to their environments, such as Richeson's use of MRI, is one of C2S's top priorities. Emma Adam, assistant professor of human development and social policy in SESP, charts levels of the stress hormone cortisol, on which she is an expert, in children, adolescents and adults in small samples of saliva.
"It's an easy way to measure everyday life experiences and psychological stress," Adam says. "In general, cortisol goes up when a situation is stressful. Cortisol provides a burst of energy in what the body perceives as an emergency situation. But if it's activated too frequently or chronically, it can cause damage to the brain and body, and impact both emotional and physical health."
For instance, Adam completed one study of kindergarten-age and adolescent children that showed a connection between high levels of conflict in the home and elevated levels of cortisol. She concluded that "fighting at home isn't just upsetting to their kids; it's potentially risking their cognitive well-being and physical health."
Adam is currently following a group of 200 adolescents over time to examine whether frequent or prolonged exposure to stress and elevated cortisol levels might influence the development of emotional disorders such as depression, phobias and panic attacks. "I'm attempting to identify both the types of social environments that activate stress hormones and the types of individuals who might be more vulnerable to the effects of repeated stress. From a policy standpoint, you can do something to alleviate stressful environments and target interventions or offer assistance to those who need it."
Other center researchers using biomarkers to measure the pernicious effects of stress in population-level health studies are Thomas McDade and Christopher Kuzawa, assistant professors of anthropology in WCAS. As a biological anthropologist, McDade studies how cultural and ecological circumstances shape human biology and health. He has conducted research in Bolivia, Samoa and Kenya using minimally invasive methods for collecting biospecimens, including drops of blood collected on filter paper - a procedure developed decades ago for newborns in hospitals. McDade adapted this technique as a tool for collecting blood samples in remote, community-based settings to measure levels of infection and immune function. He analyzes the samples for different biomarkers of physiological function and health.
For the past eight years Kuzawa has conducted extensive research on the developmental origins of adult health in the Philippines. He focuses on the role that early environments play in longevity and health, also taking nutrition, stress and other conventional risk factors into account. The findings of early environment research are sobering. Individuals who were born undernourished, or whose mothers were undernourished during pregnancy, have an elevated risk for outcomes such as hypertension, diabetes and high cholesterol in adulthood. One mechanism believed to contribute to these findings is stress hormones. Expectant mothers who experience stress can send stress hormones across the placenta, influencing the child's vulnerability and response to stress later in life and potentially elevating risks for a wide variety of diseases.
"In the old model, people said it was the genes you were born with, and your lifestyle would interact to some degree with that," Kuzawa remarks. "What we're studying now is a third perspective: You're born with it, but it's not genetic."
Within the next couple of years Chase-Lansdale hopes to see major expansions in C2S. The goals include developing more minimally invasive biomarkers, launching a summer biomarker institute and augmenting the existing lecture series. C2S and SESP faculty share a vision of studying the connection between education and health, to better understand how stress, immune function and sleep and activity patterns affect children's learning.
When it comes to unraveling the mysteries of human health, everyone at C2S concurs that the more information, the better. "By shining light from multiple perspectives, we're illuminating an all-inclusive view of health as a key aspect of human development," Chase-Lansdale muses. "It's an important new direction in science, and it's really significant for social policy. C2S gives us a broad frame that lends itself to innovation."