Podcast: Stress response varies by race, ethnicity

The podcast is available at http://www.nichd.nih.gov/news/releases/Documents/poverty_stress_021414.mp3 (MP3 - 4 MB).

Mr. Robert Bock:  Welcome to the National Institutes of Health. I'm Robert Bock. This is Research Developments, a podcast of NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development—NICHD.

All parents know that a new baby brings a lot of sleepless nights. For many families living in poverty, the stress of a new baby is compounded by other stresses: wondering where the next meal will come from, discrimination, or the threat of violence. Researchers have long known that stress plays a big role in our health.

Dr. Chris Dunkel Schetter is investigating how new parents' ethnic, racial, or economic background may influence their stress levels. In turn, she is interested in how stress might affect their health. Dr. Dunkel Schetter is a professor of psychology at UCLA. She's also the lead researcher at the Los Angeles site of the Community Child Health Network (Full Site). That's a research network supported by NICHD.

The network was set up to study disparities in maternal and child health in communities throughout the United States. She's interested in whether differences in stress response account for health differences between groups.

Dr. Chris Dunkel Schetter is on the phone with me now. With us is Mr. Peter Schafer of the New York Academy of Medicine. They are two authors of a study on the stresses of new mothers and fathers who live on low incomes. Thank you both, and welcome.

Mr. Peter Schafer: Thank you, Dr. Chris.

Dunkel Schetter: Hi, Robert.

Mr. Bock: To begin, can you tell us a little about what is known about how stress might affect health?

Dr. Dunkel Schetter: Yes, we have considerable knowledge about the effects of stress on health and know that specific forms of stress lead to earlier death and higher rates of disease. And the research attempts to understand the mechanisms have zeroed in on the effects of chronic stress—the kind of stress that is either constant in one's environment or life, or has repeatedly—kind of occurs repeatedly, over and over again. Repeated hits, as they say.

And very good work on which we based ours has been investigating the effects of chronic stress on specific body systems and how that can translate into adverse health outcomes.

Mr. Bock: So, how can stress affect body systems? What kinds of stress and what kinds of systems?

Dr. Dunkel Schetter: Well, chronic stress, for example, has effects on the immune system, on our neuroendocrine functioning, on our cardiovascular system, and those are primary—as well as metabolic effects. And those are all primary pathways that we know can lead to disease of all kinds.

Mr. Bock: OK, so chronic stress, I guess that's long-term stress, effects on the immune system. Maybe might lower the immune system, make us more liable for sickness and infectious diseases and maybe other long-term problems.

Dr. Dunkel Schetter: Chronic stress's effect on the immune system can be of two kinds. It can either make the immune system hyperactive, therefore always activated. But it also can, in some very long-term chronic stress situations, lead people to be under-responsive in their immune system. And both of those are not good for us. The immune system is meant to turn on and off in response to stress acutely, like running into a tiger in the jungle, but not meant to be chronically turned on in such a way that it either wears out or that it is constantly activated. There are profound effects of those immune factors on health.

Mr. Bock: What were the triggers of the stresses of the people that you studied? What set off the stress for these folks?

Dr. Dunkel Schetter: Well, we studied many types of stress in this study. Over the first year following the birth of a child in mothers and fathers—and Peter, maybe you'd like to mention some of those types of stress that we, in our community study, decided to focus on.

Mr. Schafer: Well, I guess it might be helpful just to think of conceptually how we kind of organize the different types of stress. And we look at a person's life and realize that stressors can come from their interpersonal and family relationships—as well as resilience factors, supportive factors, can also come from all of these domains, all of these areas. So—and we look at both resilience factors and also stressors.

But, you know, personal, interpersonal relationships, family relationships, work environment, the community environment. For example, if you live in a neighborhood that has a lot of violence and a lot of police activity, a lot of crime, that's clearly a stressor that affects people.

Just overall socioeconomic conditions that you live with. If you are financially in a precarious situation, that affects your ability to meet basic needs. That clearly affects the stress that you experience.

And so what we did is we investigated all of these different domains and we looked at different instruments that have been validated, that have been used and are out in the field. And we went through this whole process of examining them, vetting them, modifying them where necessary, in order to come up with a fairly comprehensive assessment of stress.

Then, of course, we then—I think what's sort of unique about the study, too, is we took these assessment measures, which are largely interview assessments asking people to self-report on their experiences and their reactions and stress levels, and we combined that with physiological measures of stress.

Mr. Bock: OK. So, this was a large-scale evaluation of a wide variety of different stress types—not just a few, one or two types of stress, that many other studies that have gone before you might have looked at?

Dr. Dunkel Schetter: Yes, yes. In fact, through interviews alone, we had about 10 different forms of stress, in addition to community-level measures. So it's probably the only study that's been so multifaceted in understanding multiple forms of stress.

Mr. Schafer: And likewise, this was one of the few studies that looked at poor and minority communities to this degree.

Dr. Dunkel Schetter: Yes, absolutely—one of the largest studies of diverse parents, certainly, across the United States, in different sites, different regions, who were disproportionately poor and ethnically and racially diverse.

Mr. Bock: OK. Now, before we get into the findings, I want to ask you about—you mentioned community participation, and that was a big part of this study. So, how did you get the community involved in your research, and why was that so important?

Mr. Schafer: Well, NICHD, in calling for proposals originally, required that there be at each site a partnership between an academic institution and a community partner. And they very much—NICHD very much tried to structure this in accordance with community-based participatory research principles, which, unlike most research, this approach sought to give equal power and authority in terms of determining what the research priorities would be, and so on, and the interpretation of the results, to community partners. And that's in recognition of the fact that community partners, a lot of them, are direct service providers, and public health and supportive services in communities have a unique set of experiences and knowledge that they could bring to the table. And that's my background.

I worked with an organization called Baltimore Healthy Start for many years, and we provide direct services to pregnant women and, since then, fathers of those infants in very low-income neighborhoods—very distressed communities in Baltimore. And, you know, based on that experience, we had certain ideas of what the issues were with the pathways that led to poor health outcomes because we saw among the clients their different responses.

I mean, you would have families who, in many ways, were very similar and living in similar circumstances, but then they had different outcomes. Some had very good outcomes, some had very poor outcomes, and then you get underneath the surface into the details of the circumstances of their lives, and you have some clues about what those differences are caused by.

So it's that type of experience and knowledge that this approach brought to the whole research process.

Mr. Bock: Many studies of low-income pregnant women don't include fathers, but yours did. Why did those studies leave the fathers out and why did yours include them?

Mr. Schafer: Well, I think a lot of them—I think part of it is just a conceptualization that, unfortunately, doesn't place the role of fathers and how influential they are in terms of health behaviors, in terms of material circumstances. They're basically kind of ignored. I think Chris's colleagues in L.A. did a lot of work with this in regard to: Where are the fathers in maternal and child health?

I think it's been an oversight that's perpetuated for a long time that, you know, we, hopefully, are just one of many to rectify that in future research. So, yes. And so, consciously, it was kind of against that background that we consciously decided that we needed to involve fathers in much the same way that we involve mothers. So we interviewed the fathers in the same way that we interviewed mothers. So, according to our conceptual framework, even though the primary focus outcomes were regarding maternal health and how stress affects maternal health, we understood that fathers' stress affects the relationship between fathers and mothers and thereby affects the level of stress on the mothers.

So—we just conceptualized the fathers as being integral to this whole process and, accordingly, we put a lot of emphasis on enrolling fathers in the study.

Mr. Bock: So given the scope of your study, the communities you studied, the people of different backgrounds, you did, indeed, find that people in different groups experienced stress differently. Can you tell us more about that?

Mr. Schafer: Chris, do you want to answer?

Dr. Dunkel Schetter: Yes, I would like to at least mention that the study was done in five different sites: in Washington, D.C.; in Baltimore; in Lake County, Illinois, which is just north of Chicago; and in eastern North Carolina, which is a rural area; as well as Los Angeles County.

So there were five areas that have high health disparities, including disparities in maternal/child health, that were selected. And in each site, as Peter described, there were community partners. So, in Baltimore, it was Johns Hopkins and Peter's organization. In Los Angeles, it was—I am only one of three lead investigators in Los Angeles, and our community partner makes four, so it was Dr. Calvin Hobel, Dr. Michael Lu, who was here at UCLA at the time, myself—we were the co-investigators here on the academic science side—and Loretta Jones, who is the head of Healthy African American Families, and that's a nonprofit that focuses on improving health in African American, Latino, and Korean American communities.

So each of those sites, so I won't mention the other three, had community partners, which meant that essentially a minimum of 10 lead investigators are involved in this work, and we represent that network and those many voices and many expertise brought to the program.

Mr. Bock: So with such a divergence or diversity of investigators and communities, you did indeed find many, many differences in how people experience and react to stress, correct?

Dr. Dunkel Schetter: Yes, we did. So—do you want me to answer that question? We did. We studied African American, Latino, and white mothers and fathers—approximately 2,500 mothers and approximately 1,500 fathers. We anticipated in this preliminary work on stress and disparities that stressors would be a pathway to explaining adverse outcomes; that is, the general hypothesis in the literature that we adopted is that people of low SES and racial and ethnic minority members will have—

Mr. Bock: Socioeconomic status.

Dr. Dunkel Schetter: Yes, I'm sorry. That's lower education and income—individuals of lower education and income and of African American and Hispanic minority status, ethnic and racial minority status.

Mr. Bock: So what were the differences between the groups?

Dr. Dunkel Schetter: We found, first, that the poor individuals of all ethnicities had much higher stress of multiple kinds than did those who were less poor. And so that included basically higher financial stress, which would be expected; higher pregnancy stress during the prior pregnancy; higher life events, like divorce and death in a family; many forms of higher chronic stress in the partner relationship, in the family, in the neighborhood; and higher interpersonal violence associated with poverty; and also higher parenting stress.

That was our first set of findings on them. There were two additional sets of findings.

Mr. Bock: Could you tell me about those?

Dr. Dunkel Schetter: Sure. The second one was that the effects of increasing income did not attenuate stress as greatly for African Americans as they did for whites and Latinos. The African Americans still had relatively higher rates of stress with higher income, compared to the whites. And Peter might want to say that as well.

Mr. Schafer: Yes. I mean, this is something, you know, again, the original or the umbrella under which this research was conducted was investigation of racial disparities and health outcomes. And in prior investigations in health disparities in a number of different health outcomes, it's found that when you control for income and education, sort of the standard factors by which socioeconomic status is measured, that the racial disparities persist. That is, you know, a high income and a highly educated African American woman will have poorer outcomes than a poorly educated, low-income white woman.

I mean, that is really a big puzzlement about racial disparities. It's not simply socioeconomic status, and through this—

Mr. Bock: So you're talking about how African American families, when they start doing better economically, they report feeling more stress than do other groups, notably Latinos and whites, feel when they start doing better?

Dr. Dunkel Schetter: Correct. They continue to experience very high levels of chronic stress, parenting stress, racism every day, and so on.

Mr. Bock: So, do you know what's going on there yet? Or is that—you need to look at it in future studies? I mean, is it the—?

Mr. Schafer: I think you have some indications, but I definitely think that, you know, additional research is needed, particularly in regard to workplace- and employment-related stress. These other studies have pointed to, but there's—it's as if there are—I mean, in terms of trying to explain the dynamic of what's going on here: In comparison with whites, whose higher income basically tracks very directly with lower levels of stress, and as with African Americans, that does not happen. It sort of levels out, and the stress does not decrease with higher income.

So either the protective benefits of that higher income and higher education, for whatever reasons, are not conferred among blacks as they are with whites, or there comes additional stressors with that higher income and higher education. So that's an interesting focus for future research. Like, what could be those additional stressors?

I mean, through our own research, we have some hints on what those might be, but I think there could—additional work could definitely shed more light on that issue.

Dr. Dunkel Schetter: The additional stressors is an area that there's been some research on—and that was not something our study focused on extensively, but the idea would be that with increased income, an African American may be working in an integrative setting, in a management position, for example, and may be exposed to increased discrimination in that job setting than they were at a lower level. So with the increased income comes increased exposure to very stressful everyday racism, which we did study.

The other possibility that Peter alluded to is that with increased income these stressors don't go down, as a function of either the communities in which African Americans live or discrimination that's institutional in schools or in neighborhoods. They may continue to experience very high levels of neighborhood stress and so on, parenting stress.

Mr. Bock: Now, you had mentioned—we know you studied Latino immigrants as well, and as their income went up, there wasn't the same level of stress as African Americans had experienced. But you also found a difference between Latino immigrants to the U.S. and people of Latino heritage who were born here. Could you tell us about those differences and what might account for them?

Dr. Dunkel Schetter: They're fascinating, I think. They fit with other literature and are somewhat paradoxical, and they suggest that the new immigrants experience lower stress than those who were—either immigrated longer ago or were born here of Latin American descent. And the paradox that is spoken of in the literature that seems to apply here is that life here is toxic in terms of stress, and that the longer you live here, the higher the stress is and the lower the resources that you brought along.

So, an example of that that might be an explanatory factor is the ability to rely on family and your values about familism in Latino communities, or Latino families, that may be—and we have some evidence in other studies, again—that may deteriorate, over time, living in the U.S.

Mr. Bock: So, Latinos experience less stress—the new arrivals experienced less stress than people who had been here for a generation or two?

Dr. Dunkel Schetter: Correct.

Mr. Bock: Oh, that is really interesting. And what were the sources of stress for Latinos? Was it racism or financial or other kinds of stress?

Dr. Dunkel Schetter: The Latinos were higher in parenting stress, both the mothers and fathers were higher in parenting stress than the blacks and whites in our study.

Mr. Bock: That's unusual. Could that have been that, especially for the newer immigrants, there was a question of values from the old country conflicting with values from the new country?

Dr. Dunkel Schetter: I'm not sure we know the answer to that. I don't know if Peter has a speculation.

Mr. Schafer: I mean, it's interesting. I was presenting at a conference about father involvement some of these findings and, from the audience member—other researchers suggested this whole dynamic with the difficulty on family life of having to basically work so many hours and being away from the family and being away from the children, juggling multiple jobs, multiple, insecure type of jobs, which is very common among Latino families, and that that exacerbates stress in a kind of unique fashion, and that's somewhat unique to immigrant or recent immigrant populations. So, I don't know—again, that's another area, I think, that deserves further attention.

Dr. Dunkel Schetter: And it's not uniformly the case that the recent immigrants had less stress. They actually experienced more financial stress and more racism. So, there were some—it went both ways, depending on which kind of stressor, which was what this study was uniquely useful for, is figuring out how the whole pattern of stressors in lives unfold.

Mr. Bock: Now, conversely, were there any differences in stress—did whites experience any stress that the other groups didn't?

Dr. Dunkel Schetter: Yes, for reasons that are not entirely clear, the whites were highest in pregnancy stress.

Mr. Bock: Hm. And I guess that was a surprise, that finding?

Dr. Dunkel Schetter: Well, not if you think about the fact that the whites in our studies are living in the same communities as the blacks and Hispanics and they are also disproportionately low-income and no more than middle income. So—but that is a counterintuitive finding that suggests that our platitudes about stress as one phenomena probably don't pan out very well.

Mr. Schafer: And another interesting finding regarding whites and stress is that among the lowest-income whites in the study, if we compare the lowest-income whites compared to the lowest-income blacks and lowest-income Latinos, is low-income whites had the highest levels of financial stress.

Mr. Bock: OK.

Mr. Schafer: So comparatively speaking, we're talking about folks who have the same, you know, level of deprivation in terms of economic resources. But among the three racial ethnic groups, whites felt more stress from being in that situation than the other two groups.

Mr. Bock: Hm. And, again, it's kind of hard to—

Dr. Dunkel Schetter: The fathers, not the mothers, actually.

Mr. Bock: OK, OK. Well, that sort of—that makes sense. You know, the traditional view of the male as the breadwinner. But for this group, especially, they felt it really hard.

Dr. Dunkel Schetter: So, to clarify: The white fathers in the below poverty level group had higher financial stress than the other two groups, and the white mothers in the low, below-poverty level financial group had higher pregnancy stress than the other two groups.

Suggesting, again—to me, anyway—the profound effects of poverty and how they can unfold, but differentially, maybe, with respect to some specific ethnic racial groups.

Mr. Schafer: Yes. And I mean, some speculation is perhaps the whites in those very low-income groups are more recently arrived in those very low-income groups. I don't know.

Dr. Dunkel Schetter: We haven't looked at that, but we might want to look at, in future, whether they have gone downward in their income and—

Mr. Bock: So, in other words, a lot of the white families you looked at may have come from, say, places like Eastern Europe or some other country?

Dr. Dunkel Schetter: We actually know that about them, that I think we're—you know, in disparities research, what we do is we focus in on the ethnic minority groups, and we try to understand them, and I'm very engaged in that. But I've always pointed out—we never look at the whites. We never look to find out: Are these multiple-generation? Are these new to the U.S.? You know, are they—as Peter pointed out—are the whites in the study we used for our comparison decreasing in their socioeconomic status, you know, or increasing? How are—are they the single-mother families? We don't know. I mean, that's something we have yet to look at in this study and in others.

Mr. Schafer: I mean, one thing about the study that we did do, to a large extent, and I think needs to be done more in disparities research is, as Chris alluded to, not simply looking at the racial and ethnic groups as sort of monolithic, but looking at within-group differences that are differences within African Americans, differences within whites, differences within Latino/Hispanic—because there, I think, is where it's going to be more fruitful in terms of gaining some insights in some of the dynamics, as we have. I mean, that's basically what we did when we were looking at how different racial/ethnic groups across income levels—how their stress levels react or are correlated in a different way, associated in a different way, with income. So, more along those lines, I think, will be very fruitful for future disparities research.

Mr. Bock: So, it's sort of like the story of research in general. You answer some questions, but within your answers you find new questions for new things we need to learn.

Dr. Dunkel Schetter: Yes, that—and yet, at the same time, one of our main goals in community, as well as among the scientists in this network, was to translate our findings into things that can improve these communities and their health. So we're not—we are not of a mind that we haven't learned enough yet to do that. We think that perhaps some of these findings do lend themselves to thinking about: How would we reduce stress and increase resilience factors in our communities based on these findings? And that's an area that I think we're continuing our thinking about as we finish the study.

Mr. Bock: So, yes, it is—I take it, then, you did discover these health disparities, and now we need to figure out how to address them. We don't have too much more that we can say other than that, correct?

Dr. Dunkel Schetter: Well, I mean, what we're talking about today is the first published paper from the network on disparities or differences by income, education, and race/ethnicity, and stress. What Peter and I are simultaneously engaged in is publishing our findings on about a dozen resilience factors and how they differ by race, ethnicity, education, and income. And again, that's sort of also revealing because no one has studied or even conceptualized the resilience factors as CCHN did—our network—and the findings are not straightforward. It would be really simplistic and wrong to say, "Oh, the whites were higher on all of these resources, and the Latinos or blacks were lower." The findings will be revealing there, too.

Our next step as a network is putting together these stress and resilience—many factors to understanding whether they affect the mothers' physiology during the postpartum period. So, in other words, do mom and dad's stress and resilience during the year following birth predict the mother's—what we call "allostatic load"—wear and tear on the body's systems.

And when we have been able to present those findings, then I think we'll be in a very good place to begin to make recommendations.

Mr. Bock: I see, I see. So, by resilience factors, just so we're clear, you just mean how people deal with the stress, what might protect some people—how they might deal with it better than others?

Dr. Dunkel Schetter: Well, what might help them deal with it better. And so I'll give you examples: The one most people think about is social support—so, do the moms and dads in our study have resources to rely on in their social networks, their families, and in their partnerships that give them the support to manage the stressors that were so abundant?

Another that we looked at in this network was spirituality, and we found already that African Americans with higher spirituality had lower depression over the course of that year following birth—that was true of the mothers.

We've also looked at some coping resources, at personality and individual differences like optimism, self-esteem, and mastery. And so, again, that's a very exciting area that balances the focus on stress. And we were always interested in doing more than just looking at stress.

Mr. Bock: I see, I see. So, it seems to me, the main thing is you're going to look at resilience factors now and examine them in more depth. Any additional research that you're planning?

Dr. Dunkel Schetter: We have a—this is the first paper. We have a methodology paper laying out the study that's under review. We have the resilience paper close to ready to publish, and we have a study on whether there are race, ethnic, and income differences in the biomarkers of the study that represent allostatic load. So that paper, too, is in the works.

So, I would say you can be looking for a lot of exciting things coming out of this network in the not-too-distant future.

Mr. Bock: Before we conclude, is there anything that either of you want to leave our listeners with about perhaps stress and their own health, or coping with stress, or even ways that society might address the health disparities?

Dr. Dunkel Schetter: Peter?

Mr. Schafer: Hm. [laughter]

Dr. Dunkel Schetter: I could say something while you think, and then you have to say something.

Mr. Schafer: Yes, and then I'll say something.

Dr. Dunkel Schetter: OK. Well, I'm a psychological scientist, so I come at it by saying what I've learned in the network is to respect the structural barriers and challenges that poor young parents face—and parents in general in the U.S. But despite that, and despite my recognition that we need to do things at the community level, we also do have proven, evidence-based methods of stress reduction that could be translated and used in these contexts with community participation to make sure we do it well. So I think, you know, there's at least one avenue there and probably lots more.

Mr. Bock: Hm, very interesting.

Mr. Schafer: I was focused a bit—I mean, one of many areas to focus is on social policy and government policy that affects poor families' ability to support themselves financially and to be able to live together and provide the type of social support—and having that relationship not be so much a point of conflict and stress, which is often about money and lack of money, and having it be more a positive, supportive feature of people's relationships.

There's some interesting work going on in regard to policies in terms of social welfare, cash benefits, entitlement programs, and how those programs discourage fathers' involvement in their families, and so there's some interesting initiatives aimed at reforming that and demonstrating that a change in policy could support stronger families' relationships and thereby support better health in those families.

I mean, I think, you know, just reminding us all—I mean, these differences are all very interesting, but the, kind of the primacy of low income and material deprivation as a source of stress is still there, and so that is the area, potentially, that will be most fruitful, and if we can help to alleviate and mitigate some of those stressors.

Mr. Bock: All right. Thank you both for a very interesting conversation, and I hope we can follow up with you when you get those next papers published. Thank you again.

Dr. Dunkel Schetter: Thank you.

Erratum: It was incorrectly stated that Dr. Dunkel Schetter was the lead investigator for the Los Angeles site of the Community Child Health Network. In fact, she was one of 4 leads at the Los Angeles site.

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About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's website at http://www.nichd.nih.gov/.