Studies going back to the 1950s have linked objective socioeconomic factors—like parental income or education—to child health and achievement. Recent studies have extended this research, indicating that parental socioeconomic status (SES) also affects physiologic brain function in children. A new study, while small, is the first to suggest another potent factor: the mother’s self-perceived social status.
Margaret Sheridan, PhD, at Boston Children’s Hospital’s Labs of Cognitive Neuroscience, and colleagues studied 38 children, ages 8 to 12 years. Each child gave a saliva sample to measure levels of the stress hormone cortisol, and 19 also underwent functional MRI of the brain focusing on the hippocampus, a structure responsible for long-term memory formation (required for learning) and for reducing stress responses.
Their mothers, meanwhile, were shown a picture of a ladder and were asked to rank their social status on a scale of 1 to 10 as compared with others in the United States.
After controlling for gender and age, the mothers’ self-ratings were a significant predictor of their children’s salivary cortisol: When mothers put themselves low on the ladder, their children tended to have lower cortisol levels that may indicate an impaired physiologic response to stress. This finding jives with studies in animals.
“In animal research, your stress response is related to your relative standing in the societal hierarchy,” Sheridan says.
Paradoxically, how we view our social standing may be more important than the reality.
Similarly, children whose mothers had a low perceived social status had less activation of their hippocampus during a learning task; again, maternal self-ratings significantly predicted the degree of activation.
In contrast, actual maternal education or income-to-needs ratio (income relative to family size) did not significantly predict cortisol levels or hippocampal activation in this study.
This apparent paradox suggests that while actual SES can vary dramatically, it’s how families perceive and adapt to their situation that may be more important in child development.
Such perceptions, Sheridan notes, can be influenced by culture, religious beliefs, personal values or simply one’s approach to life or feelings of self worth. “If I could find a way to reliably make people more proud of who they are, I would,” she says.
A global perspective
Sheridan’s research interest is the development of executive function, the higher-order, big-picture regulation of our varied cognitive processes, much of which starts to gel at around age 7. As a Robert Wood Johnson scholar, she became interested in studying cognition and executive function in different cultural settings. “I wanted to bring my research on SES, environment and brain development to places where there is a greater variety of experience,” she says.
She learned of a large multi-country study of childhood poverty, based in the U.K. and known as the Young Lives Project, which is looking at both objective and subjective measures of social status along with health and physiologic measures and cognitive function. “I asked to look at their data sets and found out that no one was measuring cognition the way a cognitive psychologist would,” she says.
So she talked her way into the study, joining economists, demographers and population health professionals. This past May, she set out on a two-week trip to Peru, armed with 36 Samsung tablets loaded with cognitive tests and designed with the help of a Boston-based company called NeuroScouting. Peruvian researchers from the Young Lives Project administered the tests to 12-year-old children under Sheridan’s supervision. Research settings varied from urban Lima (population, 10 million) to stone-hut villages in the Andes where interruptions in electricity and running water are not unusual.
The tests, presented as games, allow researchers to collect data on attention, memory, executive function and long-term memory. Regardless of where they lived, the Peruvian kids easily figured out how to play the “games” without having to read and with just a small amount of coaching. After watching a short movie demonstrating the task, designed with the help of NeuroScouting, they were off and running.
“Tablets are much more intuitive than a computer for someone who’s never seen a computer before,” Sheridan says. “It’s relatively easy to train people to administer these tasks, and you can also circumvent the language barrier. People noticed that even their 3-year-old could figure out how to interact with the tablet. We’re leveraging that ease of use to bring better cognitive tests to distant places.”
As a part of the same Young Lives study, the tablets recently went to Ethiopia. Ultimately, more than 3,500 children in Ethiopia and Peru who have been part of the study for the last 12 years will participate in this cognitive testing.
Data from similar tablet-administered tests also are being collected at the Boston Children’s Hospital Primary Care Center, which sees many under-served children and families from the Boston area.
While actual testing results aren’t in yet, the Peru pilot showed that it’s possible to get a measure of brain function that transcends languages and cultures. Ultimately, the work may shed more light on how our self-perceptions—filtered through different cultural lenses—can “live” biologically in our children, quite aside from actual socioeconomic disparities.