Some youngsters get depressed in the absence of any genetic legacy of the mood disorder, a new investigation finds.
Researchers report that having a depressed mother substantially ups a teenager’s likelihood of becoming depressed, even if he or she was adopted and shares no genes with the mother.
This finding provides the first direct evidence that purely environmental factors can promote depression in the children of depressed women, says a team led by psychologist Erin Tully of the University of Minnesota in Minneapolis.
Having a depressed father does not increase depression susceptibility in either adopted or non-adopted teens, Tully and her colleagues report in the September American Journal of Psychiatry.
Two other investigations, both published in the same journal, further emphasize nurture’s role in depression. They show that successful treatment of depressed mothers — either with medication or psychotherapy — spurs emotional gains in their depressed children.
“There is an environmental liability of maternal depression that cannot be accounted for by genes but that almost certainly interacts with genetic factors to create depression risk in children,” Tully says.
Depression can impair a mother’s parenting skills, cause marital conflict, and disrupt a youngster’s ties to peers and school — and these outcomes can in turn spread depression from mother to child, Tully suggests.