Washington: School-age children who get plenty of nurturing from their mothers early in life have brains with a larger hippocampus, a key structure important to learning, memory and response to stress, a new study has found.

The research by child psychiatrists and neuroscientists at Washington University School of Medicine in St. Louis is the first to show that changes in this critical region of children's brain anatomy are linked to a mother's nurturing.

"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, MD.

"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," she suggested.

For the current study, the researchers 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.

Luby believe the smaller volumes in depressed children might be expected because studies in adults have shown the same results. What did surprise her was that 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," she stated.

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 said, because the hippocampus is such an important brain structure.

When the body faces stresses, the brain activates the autonomic nervous system, an involuntary system of nerves that controls the release of stress hormones.

Those hormones help us cope with stress by increasing the heart rate and helping the body adapt. The hippocampus is the main brain structure involved in that response.

It's also key in learning and memory, and larger volumes would suggest a link to improved performance in school, among other things.

The finding has been published online in the Proceedings of the National Academy of Sciences Early Edition.