Nurturing Moms May Boost Children’s Brain Growth

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The next time you’re tempted to lose your cool with your kids, do your best to channel your inner peacenik: it’s good for your child’s brain.

School-age children whose mothers supported and nurtured them most in early childhood had a larger hippocampus, an area of the brain that is involved in memory, learning and stress response, according to a new study published in the Proceedings of the National Academy of Sciences.

Interestingly, though, the study also found that a mother’s love appeared to have less influence on the size of this brain region in children who suffered from early life depression, a condition that affects about 1% of preschoolers.

Researchers at Washington University School of Medicine in St. Louis studied 92 children who were participating in an ongoing study of childhood depression. Forty-one children had been diagnosed with clinical depression by preschool age; the others served as a control group.

When the children were between 4 and 7 years old, the researchers observed them interacting with their mothers in a mildly stressful situation. The mothers and children were left in a room with a brightly wrapped present. The kids were told they could open the package, but they had to wait until their parent finished some paperwork.

MORE: Kids Behaving Badly? Blame It on Mom

During the eight-minute lag, the researchers assessed the mothers’ behavior toward the children. Did moms reassure their kids and support their efforts to remain patient and control their impulses? Or was the mother the less nurturing type, ignoring or scolding the child?

When the children were between 7 and 10 years old, the researchers brought them in for brain imaging. The scans showed that those whose mothers had been most supportive several years earlier had a significantly larger hippocampus — on both sides of the brain — nearly 10% larger than the same regions in children with less empathetic mothers.

The hippocampus is crucial for recording and processing memory, a key function that predicts kids’ learning and performance in school. The region is also believed to be important in regulating stress, but is threatened when the body’s levels of stress hormones get too high. Previous research suggests that the effects of stress hormones on the hippocampus may help explain the link between stress and depression: when toxic levels of stress hormones cause shrinkage of the hippocampus, depression may result. During recovery, the region sprouts new cells.

In the current study, the link between brain growth and maternal support seen in mentally healthy children did not reach statistical significance in those with early life depression. What this means is still unclear. It could be that good mothering is not powerful enough to counter the brain effects of depression. Or, looked at another way, it could mean that a mom’s nurture helps prevent early depression from doing even more damage. Perhaps it may also protect against depression that occurs later in life. The study wasn’t able to measure these effects.

MORE: Study: How Chronic Stress Can Lead to Depression

What the research did show is that in normal children, having a supportive mom is “directly related to healthy development of a key brain region known to impact cognitive functioning and emotion regulation,” as the authors put it.

The findings provide evidence that the same phenomenon seen in animals is also true in humans: previous research in rats has found that maternal nurture in early life — manifested as  licking and grooming — is linked with a larger hippocampus, better memory and a greater ability to cope with stress. In contrast, maternal neglect harms the hippocampus and makes rats more prone to the rodent equivalent of depression.

“For years studies have underscored the importance of an early, nurturing environment for good, healthy outcomes for children,” said study author and professor of child psychiatry Joan Luby in a statement. “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% larger just provides concrete evidence of nurturing’s powerful effect.”

Children aren’t the only ones boasting bigger brains: moms are too. In 2010, a study in Behavioral Neuroscience found that women’s brains may actually increase in size during new motherhood, particularly in mid-brain regions associated with pleasure and in the prefrontal cortex, which is linked to reasoning, judgment and planning — something all mothers do a lot of.

MORE: A Mother’s Love May Counter Some Ill Effects of Poverty

Follow Maia Szalavitz on Twitter at @maiasz, and Bonnie Rochman at @brochman. You can also continue the discussion on TIME Healthland’s Facebook page and on Twitter at @TIMEHealthland.