All those hugs and kisses you give your toddler when she skins her knee, waves goodbye at preschool, or gets tucked into bed may be even more beneficial than you thought.

A new study shows that the brains of early-nurtured kids have a larger hippocampus. That may make it easier for them to learn, improve their memory, and even respond to stress.

Child psychiatrists and neuroscientists at Washington University conducted brain scans on children who had participated in an earlier study as preschoolers. The kids with the most nurturing parents ended up with a hippocampus 10 percent larger than the other children.

"For years studies have underscored the importance of an early, nurturing environment for good, healthy outcomes for children," said lead author Joan Luby. "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 took brain scans of 92 kids ages 7 to 10 who had been part of an earlier study of preschool depression. In the first study, observers rated parents on how they were able to nurture their toddler as he or she waited to open a present. The imaging revealed that mentally healthy children who had been well-nurtured had a hippocampus almost 10 percent larger than children whose mothers were rated as not as nurturing.

NEWS: Supermom Primates Raise Twins

The research did not show that nurturing helped kids who showed early signs of depression, however. That could mean depression has its own effect on the hippocampus, or that nurturing comes into play earlier on in a child's life. Luby said the smaller volumes in depressed children might be expected because studies in adults have shown the same results.

NEWS: Children's Self-control Predicts Health, Wealth

Study authors hope that educators use the information to help parents work with their children.

"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," Luby said.

Photo: iStockPhoto