A mother’s affection during the early stages of a child’s life appears to help the development of an area of the brain involved in learning, memory and stress response.
Researchers from Washington University School of Medicine in St. Louis determined school-age children whose mothers nurtured them early in life have brains with a larger hippocampus. The hippocampus is a key structure important to learning, memory and response to stress.
The research is published online in the Proceedings of the National Academy of Sciences Early Edition.
“This study validates something that seems to be intuitive, which is just how important nurturing parents are to creating adaptive human beings,” said first author Joan L. Luby, M.D.
“I think the public health implications suggest that we should pay more attention to parents’ nurturing, and we should do what we can as a society to foster these skills because clearly nurturing has a very, very big impact on later development.”
Researchers performed brain-imaging on children ages 7 to 10 who had participated in an earlier study of preschool depression approximately 10 years prior.
That study involved children, ages 3 to 6, who had symptoms of depression, other psychiatric disorders or were mentally healthy with no known psychiatric problems.
As part of the initial study, the children were closely observed and videotaped interacting with a parent, almost always a mother, as the parent was completing a required task, and the child was asked to wait to open an attractive gift.
How much or how little the parent was able to support and nurture the child in this stressful circumstance — which was designed to approximate the stresses of daily parenting — was evaluated by raters who knew nothing about the child’s health or the parent’s temperament.
“It’s very objective,” said Luby, a professor of child psychiatry. “Whether a parent was considered a nurturer was not based on that parent’s own self-assessment. Rather, it was based on their behavior and the extent to which they nurtured their child under these challenging conditions.”
One criticism of the study is that researchers didn’t observe parents and children in their homes or repeat stressful exercises. However, other studies of child development have used similar methods as valid measurements of whether parents tend to be nurturers when they interact with their children.
In the current study, scientists conducted brain scans on 92 of the children who had had symptoms of depression or were mentally healthy when they were studied as preschoolers. The imaging revealed that children without depression who had been nurtured had a hippocampus almost 10 percent larger that children whose mothers were not as nurturing.
“For years studies have underscored the importance of an early, nurturing environment for good, healthy outcomes for children,” Luby said. “But most of those studies have looked at psychosocial factors or school performance.
“This study, to my knowledge, is the first that actually shows an anatomical change in the brain, which really provides validation for the very large body of early childhood development literature that had been highlighting the importance of early parenting and nurturing.
“Having a hippocampus that’s almost 10 percent larger just provides concrete evidence of nurturing’s powerful effect.”
Researchers say it is logical that the hippocampus is smaller among depressed children as adult studies have demonstrated similar results. What was surprising was how nurturing made such a big difference in mentally healthy children.
“We found a very strong relationship between maternal nurturing and the size of the hippocampus in the healthy children,” Luby said.
Although 95 percent of the parents whose nurturing skills were evaluated during the earlier study were biological mothers, the researchers say that the effects of nurturing on the brain are likely to be the same for any primary caregiver — whether they are fathers, grandparents or adoptive parents.
The fact that the researchers found a larger hippocampus in the healthy children who were nurtured is striking, Luby says, because the hippocampus is such an important brain structure.
Investigators say the hippocampus is a key structure for regulating the involuntary release of stress hormones. The system is activated when the body faces stresses, as the hormones help us cope with stress by increasing the heart rate and helping the body adapt.
The hippocampus is also key in learning and memory, and a larger size hippocampus would suggest a link to improved performance in school, among other things.
Luby said educators who work with families who have young children may improve school performance and child development by not only teaching parents to work on particular tasks with their children but by showing parents how to work with their children.
“Parents should be taught how to nurture and support their children. Those are very important elements in healthy development,” Luby said.