Mother's perceived social status affects child's brain development and stress level
How a mother perceives her social status can predict her child’s brain development and stress indicators, according to a new study at Boston Children's Hospital, published August 6 in the journal Developmental Science.
Although prior studies from the 1950s have shown a link between child health and socioeconomic status (e.g. a parent’s income and educational level), this latest study is the first to associate a child’s brain function with their mother’s self-perception.
The study found that mothers perceiving themselves to have low social status, tended to have children with higher cortisol levels, an indicator of stress. Higher cortisol levels also lessen activity in the child’s hippocampus, a structure in the brain responsible for reducing stress and storing long-term memories, which is required for learning.
"We know that there are big disparities among people in income and education," says the study’s lead author Margaret Sheridan, PhD, of the Labs of Cognitive Neuroscience at Boston Children's Hospital. "Our results indicate that a mother's perception of her social status 'lives' biologically in her children."
For the study, Sheridan and senior investigator Charles Nelson, PhD, along with colleagues from Boston Children's Hospital, examined saliva samples from 38 children between the ages of 8.3 and 11.8 years to measure levels of cortisol. Nineteen of those children also had a functional MRI of the brain that focused on the hippocampus.
In the meantime, the mothers of the children were asked to rate their perceived social status on a scale of 1 to 10, comparing themselves with others in the United States.
As a result, the research team found the following:
• The mother's self-perceived social status was a significant predictor of cortisol levels in the child after controlling for gender and age. This finding is consistent with studies in animals. "In animal research, your stress response is related to your relative standing in the hierarchy," explained Sheridan.
• Similarly, the mother's perceived social status significantly predicted the degree of hippocampal activation in their children during a learning task.
• In contrast, the mother’s actual education and income level did not significantly predict cortisol levels or hippocampal activation.
Although actual socioeconomic status varies, these findings show that how people perceive and adapt to their social standing plays an important role in child development. By the same token, Sheridan is careful to point out that some of this may be culturally determined.
Meanwhile, Sheridan is now involved in a much larger international study of childhood poverty that is looking at objective and subjective measures of social status along with health measures and cognitive function. The study, called the Young Lives Project, will reveal even broader extremes of socioeconomic status in other parts of the world that is rarely, if ever, seen in the U.S.
One thing this latest study did not show was any evidence that high stress levels alter hippocampal function, nor was any link found between cortisol and hippocampal function, such as what has been found in animals. This could be due to the small number children having brain fMRIs.
"This needs further exploration," says Sheridan. "There may be more than one pathway leading to differences in long-term memory, or there may be an effect of stress on the hippocampus that comes out only in adulthood."
SOURCE: Margaret A. Sheridan, Joan How, Melanie Araujo, Michelle A. Schamberg, Charles A. Nelson. What are the links between maternal social status, hippocampal function, and HPA axis function in children? Developmental Science, 2013; DOI: 10.1111/desc.12087