Childhood adversity is linked to chronic stress in adolescence, setting the stage for a host of physical and mental health problems, finds a new Cornell study published online in July in Psychological Science.
The longitudinal study found that the greater proportion of childhood spent in poverty, the greater number of risks children were exposed to, and this was linked to increased markers of chronic stress by the time the children were 17.
For their analysis, the researchers used survey data on 173 children that included information about family income and exposure to such risks as housing conditions, family turmoil and violence. Children's blood pressure, overnight levels of stress hormones and body mass index were measured to assess physiological changes, known as allostatic load, which are associated with chronic stress.
"While prior work has shown that childhood poverty is linked to elevated chronic stress, as indicated by allostatic load, this study adds two critical ingredients: We demonstrate this in a prospective, longitudinal design which makes the evidence stronger, and we show that the poverty-allostatic load link is explained in part by low-income children's exposure to cumulative risk factors," said lead author Gary W. Evans, the Elizabeth Lee Vincent Professor of Human Ecology in Cornell's College of Human Ecology. He conducted the study with Pilyoung Kim, Ph.D. '09, now an assistant professor at the University of Denver.
"In other words, one reason why poverty leads to chronic stress is because of the confluence of risk factors poor children encounter," Evans said.
The cumulative effect of these risks can add up to levels of stress capable of damaging the developing brain and body and setting a trajectory for future disorders, the authors said.
"Poverty often leads to chaotic circumstances that make it more difficult for children to get what they need to develop optimally," Evans said. "Chaos makes it difficult to sustain predictable and increasingly complex exchanges between caregivers and the growing child. Furthermore, this chaos occurs across many of the settings in which the children's lives are embedded, such as neighborhoods and schools.
"Based on what we're learning about the harmful and long-term effects of chronic stress on child development, we need to broaden our thinking about how we can improve the life prospects of children at risk and we need to make these investments early in life before the adverse effects of stress are encoded in the developing child," he said.
This research was funded by the W.T. Grant Foundation and the John D. and Catherine T. MacArthur Foundation Research Network on Socioeconomic Status and Health.
Karene Booker is an extension support specialist in the Department of Human Development.