Early childhood poverty has been linked to smaller brain size by U.S. researchers who are pointing to the importance of nurturing from caregivers as a protective factor.
Children exposed to poverty tend to have poorer cognitive outcomes and school performance. To learn more about the biology of how, researchers started tracking the emotional and brain development of 145 preschoolers in metropolitan St. Louis for 10 years.
Household poverty was measured by the income-to-needs ratio. Children were assessed each year for thee to six years before they received an MRI and questionnaires. A parent and child were also observed during a lab task that required the child (age four to seven) to wait for eight minutes before opening a brightly wrapped gift within arm's reach while the parent filled in questionnaires.
"These study findings demonstrated that exposure to poverty during early childhood is associated with smaller white matter, cortical grey matter, and hippocampal and amygdala volumes," Dr. Joan Luby of the psychiatry department at Washington University School of Medicine in St. Louis and her co-authors concluded in Monday's issue of the journal JAMA Pediatrics.
The findings were consistent with an earlier study by the same team that suggested supportive parenting also plays an important role in the development of the hippocampus in childhood independent of income. The brain's hippocampus is important for learning and memory and how we respond to stress.
In the study, the effects of poverty on hippocampal volume was influenced by caregiving support or hospitality in the brain's light and right hemispheres and stressful life events on the left. Caregiver education was not a significant mediator.
Protect young minds
Children who receive more nurturing caregiving may also be protected from exposure to stressful life events, the researchers said.
Since the data came from a larger study on symptoms of depression, the researchers acknowledged the findings may not apply more widely.
The study began when the children were in preschool, but there is every reason to believe the mediating effects of caregiving quality and stress began much earlier in life, Charles Nelson of Boston Children's Hospital said in a journal editorial accompanying the study.
"If we wish to protect our children's brains, we must work hard to protect their young minds," Nelson said. "Exposure to early life adversity should be considered no less toxic than exposure to lead, alcohol or cocaine, and, as such, it merits similar attention from public health authorities," when designing screening and intervention strategies for high-risk families.
Last year, the American Academy of Pediatrics concluded that strong and frequent stress for children, such as from living in substandard housing with adults who are also stressed, can disrupt healthy brain development.
The study was funded by the U.S. National Institutes of Health.