In the September issue of the journal Developmental Psychology, researchers report on a study of adopted babies to explore the question of how much the environment matters when it comes to a risk for depression.
All 281 of the families in the study had adopted infants. The researchers gathered information on the biological mother and adoptive parents and assessed the parent-child interactions at 9 months, and then again at 18 months.
If the adoptive mom showed signs of depression at 9 months, the child was more likely to be fussy at 18 months. But what about when it was the birth mom who was depressed?
If the biological mother had depression, the baby was more likely to be fussy at 18 months, but only if the parents of that baby were unresponsive and cold. If the baby of a biological mom with depression was comforted and given more positive feedback, the baby was not more likely to be fussy or show emotional distress later on.
The take away from the study is that genes do matter, but the environment can trump DNA when it comes to depression. The heritability of depression is estimated at 50 percent, so what the study points to is that there is a lot of wiggle room — and parent-child interactions are sure to play a big part.
My only other question: is fussiness in an 18-month-old a good indicator that the child will later be clinically depressed? I’d be interested to see if these researchers are going to follow the babies as they grow up.
More from Heather Turgeon: