Links between normal variations in parenting and a baby’s brain development have been found in a study involving 352 mothers and their babies.

Annie Bernier at the University of Montreal and colleagues observed mothers playing with their 5-month-old babies for two minutes and coded the interactions. Then they ran an electroencephalogram (EEG) test on the baby there and then, and did so again when the baby was 10 months old and 24 months old.

The EEG reading looked at “frontal resting EEG power”, which increases during an infant’s development and is associated with things like working memory.

They found that babies of mothers who behaved positively towards their infants (tone of voice, facial expressions) and who did not overly physically stimulate them showed a slightly but statistically significantly higher rate of increase in the measure from 5 to 10 to 24 months. They controlled for some other things that also influence these measures, such as the mother’s age and education and the infant’s gender.

They did not find any correlation, however, with mothers’ intrusive behaviour in children’s play or mothers’ sensitivity to children’s signals. It is difficult to understand why such closely related factors are correlated differently. The researchers speculate whether this has something to do with the imperfect method of coding the mother’s behaviour.

The study does not prove a causative link between a mother’s behaviour and the brain changes, but other studies have demonstrated causative effects from maternal behaviour, albeit in experiments with much more extreme cases than the normal parenting patterns looked at in this study.

The authors conclude, “Evidence is beginning to support the long-standing suggestion that normal variations in maternal care can influence a young child’s brain development.”

The authors recommend further studies that take into account other family members’ interactions with an infant – fathers’, grandparents’ and others’.