Alison Wismer Fries and her colleagues at the University of Wisconsin-Madison compared 21 typical youngsters from Milwaukee to 18 children who had been adopted by Milwaukee area residents after spending their first year or so in Romanian and Russian orphanages. Using urine samples, they found that the adopted orphans had significantly lower levels of vasopressin--a hormone that plays a role in familial recognition--circulating in their systems than their peers.
The scientists then had the two groups of children play an interactive computer game with their mothers and, later, an unfamiliar woman. The 30-minute game involved timed "tickling, patting on the head, counting each other's fingers, [and] whispering in each other's ears." Studies in animals have shown that such pleasant physical contact leads to a rise in oxytocin levels--a hormone that seems to help form secure relationships--particularly when the touch comes from a relative. Although the family-reared children showed the expected rise in oxytocin levels when touched by their mothers, the orphans did not exhibit as strong a response.
"We had a rare opportunity to examine children who were reared in extremely aberrant social environments where they were deprived of the kind of care-giving typical for our species," the authors report online this week in the Proceedings of the National Academies of Science. "The results of this experiment suggest a potential mechanism whose atypical function may explain the perverse social and emotional difficulties observed in many children who have experienced aberrant caregiving."
The researchers caution that this does not mean that these children are functionally incapable of forming healthy relationships, but note that the findings may explain why such orphans show an affinity for comfort from strangers or difficulties developing friendships, among other potential challenges. "All we are saying is that in the case of some social problems, here is a window into understanding the biological basis for why they happen and how we might design treatments," team leader Seth Pollak says.