Although scientists can’t yet be sure what influences a child’s development the most – nature or nurture – it has been long known that both are incredibly important and complementary to each other. It’s difficult to track the effects on both over time, however, as many factors come into play.
A new study, published in the Proceedings of the National Academy of Sciences, has tracked the neurological development of 127 children throughout their early lives, right up to early adolescence. By looking at changes in the hippocampus – the region of the brain primarily associated with memory formation – over such a long time, they were able to confidently come to a remarkable conclusion: maternal support through childhood causes their hippocampi to more than double in size.
“This study suggests there’s a sensitive period when the brain responds more to maternal support,” Joan L. Luby, a child psychiatrist at St. Louis Children’s Hospital and Washington University, and lead author of the study, said in a statement.
A member of the research team monitoring a mother and child complete a cooperation-reliant puzzle. Washington State
The hippocampus is strongly associated with the consolidation of memories from the short-term into the long-term, as well as the regulation of stress and the ability to navigate three-dimensional spaces. The better the hippocampus develops, the “smarter” the person tends to be.
Although there has been some suggestions in the past that the average hippocampus size varies between men and women, this was recently shown to be untrue. However, people do have different hippocampus volumes, and the researchers behind this study wanted to know how much “nurture” influences this as brains develop during childhood.
The children chosen for their study had three waves of magnetic resonance imaging (MRI) scans – a technique of measuring the dimensions of and blood flow to structures in the brain – throughout their young lives, from preschool age to the start of adolescence. The level of maternal support throughout their early lives was also tracked.
Pre-school support was estimated by giving the participants a patience-straining task. A present was placed before each child, who then had to wait for 8 minutes, supervised by their mothers, before they were allowed to open it. The more supportive the mother was in keeping the child happy and unstressed during the wait, the higher the score they were given.
School-age support was estimated by asking both mother and child to solve a jigsaw of the U.S. together. Only the parent could see the pieces though, so they had to help the child piece it together. Once again, the more supportive and ultimately successful they were, the higher the score they were given.
By the end of the study, the families that showed the highest level of maternal support – particularly during the preschool years – also showcased the sharpest rise in hippocampal volume. High levels of support could result in an incredible 2.06 times increase in volume compared to a child receiving below average support.
Comparing hippocampal volume changes to the level of pre-school maternal support. The correlation is definitely stronger with the left segment. Luby et al./PNAS
This hippocampal volume increase wasn’t correlated with increased IQ, however, although it was linked to better emotional development. Conversely, children that had poor pre-school support, but good school-age support, still had relatively small hippocampi.
“The parent-child relationship during the preschool period is vital,” Luby concluded. “We think that’s due to greater plasticity in the brain when kids are younger, meaning that the brain is affected more by experiences very early in life."
Although the study focused on the mother-child relationship, there is no evidence to suggest an attentive father wouldn't produce the same results.