Cognitive responses to stress link socioeconomic status and incidence of disease
The rich get richer, those in the middle drift downstream, and the poor fall farther behind. Might that widening gulf of inequality in the world’s wealthiest nation be responsible, at least in part, for that nation’s relatively poor health, despite boasting the world’s most advanced medical technology? Psychological investigators not only see a strong link between wealth disparity and health, they are developing a body of evidence to explain it.
The Bureau of the Census reported recently that another 1.7 million people in the United States slipped below the poverty line in 2002, bringing the total to 34.6 million. Most of the “new poor” were African Americans, suburbanites, and from the Midwest. Another telling statistic: median cash income dropped 1.1 percent in 2002, down 3.4 percent since 1999. But this snapshot obscures deeper, more long-term realities – the widening income gap between the best-off and the rest, and the dwindling middle class.
That growing gap in the distribution of wealth has gone largely unnoticed, but as Paul Krugman reported a year ago in The New York Times Magazine, “For at least the past 15 years, it has been hard to deny the evidence for growing inequality in the United States. Census data clearly show a rising share of income going to the top 20 percent of families, and within that top 20 percent to the top 5 percent, with a declining share going to families in the middle.” The middle class, he says, is vanishing. The richer you were a few short decades ago, the faster you grew even richer.
- From 1979 to 1997, according to the Congressional Budget Office, the after-tax income of the nation’s top 1 percent of families rose 157 percent, compared to 10 percent for those near the middle.
- By 1998, the top .01 percent, some 13,000 taxpayers, had incomes averaging $17 million, 300 times that of average families, and their total nearly equaled that of the 20 million poorest households.
- From 1970 to 1999, the top 100 corporate executives reaped a 29-fold paycheck whirlwind, from $1.3 million to $37.5 million, from 39 times the average worker’s pay to more than 1,000 times that average.
“We are now living in a new Gilded Age,” Krugman wrote, “as extravagant as the original. … [T]echtonic shifts … have taken place in the distribution of income and wealth in this country. My sense is that few people are aware of just how much the gap between the very rich and the rest has widened over a relatively short period of time.”
“The rising tide has not lifted all boats,” agreed APS Fellow and Charter Member Jeanne Brooks-Gunn, Columbia University Teacher’s College, who researches poverty’s effects on children. “The bottom 40 percent have stagnated and, if you have not completed high school, you are earning less than your father earned. Since 1979, real wages after inflation have gone down for both high school graduates and dropouts. That is a crisis in terms of what it means for families who are really struggling,” said Brooks-Gunn, a James McKeen Cattell Fellow Award recipient.
It’s increasingly apparent that the income disparity is damaging the nation’s health – the United States claims higher infant mortality than Sweden, shorter life expectancy than Canada, Japan, and Western Europe, and for each rung down from the top of the economic ladder, higher ratings on a host of risk factors for diseases.
The linkage between socioeconomic status and health has been known at least since the first Whitehall study in England during the 1960s. “If you wanted to predict an individual’s overall health and longevity and could have only one bit of information,” said APS Fellow and Charter Member Nancy Adler, University of California, San Francisco, “you would want to know the person’s socioeconomic status. This is perhaps the single strongest determinant of health.”
And it’s not how poor you are, but how poor compared to others in your community or society. Presumably, the wider the gulf, the more dire the overall consequences.
Not only have Whitehall I and its 1980s successor, Whitehall II, found that 10-year mortality increases with each step down the civil service ladder, from the highest administrative grades to janitors and mail clerks, but also that those effects persist into old age. What the stepwise linkage shows is that extreme poverty and lack of access to health care aren’t the major culprits, because all the Whitehall subjects had jobs and access to the United Kingdom’s National Health Service.
Access to health care accounts for only a small part of health disparity, according to Adler, who chairs the John D. and Catherine T. MacArthur Foundation’s Research Network on socioeconomic status and health. The network, an international group of 14 core researchers, is exploring the pathways by which socioeconomic status, or SES, gets “under the skin.” Among these paths are behaviors, psychosocial factors like stress, lack of personal control, hostility, and depression, and physical and social conditions such as pollution, toxins, crowding, and violence.
One player on the field is “reserve capacity.” The basic idea, Adler explained, “is that, like money in the bank, higher SES endows individuals with more psychological reserves that provide buffering against adverse situations.” Another player is “allostatic load,” the collective score of bodily wear and tear caused by repeated exposure to stress – for example, higher cholesterol, or malfunction of the hypothalamic-pituitary-adrenal axis, the fight-or-flight cortisol machine.
These two elements – allostatic load and the reserve capacity to counter it – point to “a central role of stress, and affective and cognitive responses to that stress, as important pathways from SES to disease,” Adler said. “We are moving up the learning curve. On allostatic load, for example, we now have data linking it on the one hand to socioeconomic status and on the other to disease risk and mortality.”
A social epidemiologist in the MacArthur Foundation’s Research Network, Ichiro Kawachi, Harvard University, has also found that communities with greater income inequality are lower on measures of social capital, and that this accounts for much of the increased mortality. “What we don’t yet know,” Adler said of Kawachi’s work, “is whether these effects are uniform across the population. Is health worse for both rich and poor in more unequal societies, or is it particularly bad for those nearer the bottom?”
An emerging concept is subjective social status – where individuals themselves think they are on the socioeconomic ladder, independent of income, education, and occupation, the objective measures of that status. It turns out that what you think your social status is has as much or more to do with your health status than where the objective measures say you are.
In a follow-up to Whitehall II, Adler’s team asked almost 7,000 British civil servants where each thought he or she was on a 10-step social ladder and found “a higher prevalence of angina, diabetes, respiratory illness (in men), poor self-rated-health, and depression” among those who think they have low social status compared to those who think their status is higher. “It seems very likely,” Adler concluded, “that subjective status reflects an individual’s socio-cultural circumstance more fully than any of the objective measures.”
She and her colleagues have now tested their subjective social status ladder among American white women, finding that those who think they’re higher up the ladder have better self-rated health, smaller waist-to-hip ratios, shorter sleep latency, lower heart rates, and better cortisol regulation. They’ve also tested it with a diverse group of pregnant women to look for racial differences, and with adolescents to track how their perceptions of social status shift as they moved toward early adulthood.
Much work still needs to be done to document how socioeconomic status-related psychological factors influence health, but Adler says it’s time to ask, “If we identify some of the key psychological mediators, how do we modify them to improve health?”
One way is to intervene in early childhood. But if the road out of poverty and its associated health risks is paved with education, that road, too, is pockmarked with potholes. “It is estimated that as many as one-third of kindergartners may not be considered by their teachers to be ready for school,” Brooks-Gunn told a Congressional briefing in 2000, “and the proportions may be much higher in communities serving large numbers of poor children.”
“We’ve done quite a bit of work showing that poverty in the first years of life is more predictive of school completion and achievement at 18 than poverty in adolescent years,” she said. “Kids who are poor in the first five years of life look very different when they reach the school door, and those differences are not overcome by subsequent schooling.”
Poverty and near-poverty are associated with cognitive development, achievement, and behavior problems from about age two through age five, she said. And the effects increase during elementary school, probably because schools are not reducing the disparities of those preschool years when parents’ mental health, parenting styles, the quality of mother-child interactions, the physical condition of the home and neighborhood, and early opportunities for learning all have profound effects on a child’s development.
One goal of early intervention, Brooks-Gunn told Congress, “is to diminish the SES disparities in the preschool years so that poor children enter school on a more equal footing to their more affluent peers. … [But] if policy makers believe that offering early childhood intervention for two years, or even three, will permanently and totally reduce SES disparities in children’s achievement, they may be engaging in magical thinking.”
That’s because after the preschool intervention, poor children are more likely to face continuing obstacles to success: schools that aren’t conducive to learning, and neighborhoods with high levels of violence, asthma-inducing pathogens, and unsafe play areas. Their parents are also more likely to live with the stresses of transportation problems and discrimination in housing and jobs.
Like adults, children pay for poverty with physical health problems. But, Brooks-Gunn said, less is known about those. “We do know that there are social class disparities on physical health, such as low birth weight, which sets the stage for what will happen later on. Also, the increase in asthma and obesity among children and youth living in poverty is fairly dramatic.”
Obesity is particularly problematic. Poor children get less exercise because their schools are less likely to have safe playgrounds, physical education, or safe and affordable places for after-school physical activity. They also eat more junk food and spend more time watching TV. Added together, Brooks-Gunn said, “You’ve got the makings for an SES disparity for obesity in children and youth, and if you are obese as a child or adolescent, you are much much much more likely to be obese as an adult. And, of course, obesity is related to early mortality in adults. Obesity has not been given as much attention by researchers as it should. I believe you’re going to see more attention being paid to it and more efforts at altering the high rate of obesity among both adults and kids.”
Despite impressive beginnings, she said, “The file of how economic status gets under the skin to affect youth and health is just beginning. I see it as one of the most exciting pieces of work being done right now in people who study children and youth. We’re starting to get glimmers of how this works, but we don’t yet have as much information on linking these family processes to physiological processes. This is just starting, and many of us are asking where will this all lead.”
One likely destination parallels Adler’s stress-related findings among adults. Studies of children raised in Romanian orphanages show that “their stress reactivity system looks different from those of children raised in families,” Brooks-Gunn noted. “Extreme deprivation and stress may lead to a young child’s having difficulty modulating information coming in from the environment. Their physiology may respond to even normal challenging events, like going to school, very dramatically,” either with too much cortisol production or not enough. Research with Holocaust survivors has shown that the response system can be affected even 40 or 50 years later.
“That, to me, is beyond belief,” Brooks-Gunn said. “Every time I look at these data I’m just blown away. Now, what people are trying to do is look at children in less extreme conditions than orphanages and see whether certain experiences in life could be related to disruptions in how the body responds to new situations.”
Researchers from her Center for Children and Families at Columbia University are testing children at home and checking their cortisol levels to see how high they rise under stress, and how quickly they return to baseline afterwards. They are doing this with 300 third-, fourth-, and fifth-grade students from all income levels except the highest 20 percent.
“We’re looking at whether we see social class disparities in their responses,” Brooks-Gunn explained, “and if so, what might account for those, and whether some of these effects can be buffered or amplified by the kind of interactions that the kids are having with their parents.” In the last of four years of data collection, “we’re finding that third- and fourth-graders who stay up later or who have more variable bedtimes have higher cortisol ratings in the morning. Now we’re going back to try to understand who are the kids who have these later bedtimes or more irregular bedtimes. Maybe something that simple, lack of routine, affects cortisol production.”
Other investigators are trying to learn whether and how socioeconomic class in early life may be linked to adult health status. “People have talked about sleeper effects,” Brooks-Gunn said. “There may be intermediate ways in which health is being influenced that none of these longitudinal studies we’ve done are picking up.”
She’s following yet another investigatory path – neighborhood and environmental influences – in two separate projects. For seven years one project tracked children in 6,000 families from 80 randomly selected Chicago neighborhoods. Brooks-Gunn is now analyzing the data to understand whether and how much neighborhood characteristics are associated with mental and physical health, achievement, crime, delinquency, and other indicators.
In the second study, “Moving to Opportunity,” she is analyzing data from a 1996-98 trial by the US Department of Housing and Urban Development in which public housing residents were randomly assigned either to remain in their housing project, to receive a voucher to move to a poor or near-poor neighborhood, or to get a voucher to move to a neighborhood with fewer poor. Brooks-Gunn’s five-year follow-up is finding “a fairly big reduction in anxiety and depression in the adults, typically the mothers, and some evidence of reduction in anxiety in kids from moving to the more affluent neighborhoods.”
Socioeconomic status research clearly has important public policy implications. “One of the difficult issues,” Adler said, “is the tension between addressing income differentials through policies that encourage income redistribution, and addressing the psychological consequences, which looks like we’re allowing injustice to continue by diminishing some of its bad effects. My own view is that we need to do both. We are unlikely to have massive income redistribution in current society, and we want to alleviate some of the harm that is now done.
“Given the history of discrimination in our country, we also have to address the relationship of SES to race and ethnicity. Because our national data for a long time only had information on race, many of the health disparities have been reported by race, and this has contributed to a ‘biologizing’ of race. Showing that many of these differences are due not to race but to social disadvantage may help push for policies that reduce such disadvantage rather than just focusing on treatment of the resulting diseases.”
Health behaviors present yet another policy battlefront. “We know that health behaviors are the single greatest contributor to premature mortality. I’ve been giving talks on ‘behavioral justice.’ We don’t want to ‘blame the victim’ by saying that lower SES people engage in more health-risking behaviors. If we understand the extent to which these behaviors are shaped by physical and social environments associated with SES, this shifts it to an environmental focus. Just as the environmental justice movement has galvanized public opinion to oppose policies that unjustly expose poorer communities to environmental risk, behavioral justice focuses on the inequality of access to resources to engage in healthy behaviors.”
Adler notes that health and mortality disparities are due far more to who gets sick than to differences in their treatment, but focusing narrowly on treatment “has made us less aware of the importance of preventing disease in the first place. We will not achieve the Healthy People 2010 goal of eliminating health disparities without addressing prevention. Within this, those of lower SES will need more time and help to engage in healthy behaviors, since they are living and working in less supportive environments.”
Brooks-Gunn’s own research has also highlighted a range of policy issues. “Our work on early maternal employment suggests we need better policies for family leave, like paid leave after the birth of a baby. Even poor countries have paid leave, at least in part. Greece has it. So does South Africa. All of the industrialized countries have it. Every single one of them.
“And our work on early childhood education … [suggests] a variety of policies related to offering education programs to children before kindergarten. We need to think of creative ways to increase the number of children exposed to those programs.”
As she asked at the Congressional briefing: “If an early childhood program promotes stable maternal work and presumably somewhat higher family incomes, fewer days of missed work, and more stable employment, will we add this into our cost estimates of future early childhood intervention evaluations?”
Her research demonstrates that early childhood intervention has larger effects than efforts in later years, and that those effects continue through elementary school. Although diminished, she argued, “they are still larger than the immediate effects of other, later interventions. If the sum of the largest effects in the educational literature is not large enough, what do we want?”
That, in essence, is the broader question socioeconomic status research is posing to American society.
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