One study directly assessed the brain functioning of children in foster care using the popular method of examining levels of cortisol, the hormone produced in
response to stress in humans.25, 26 Children who are exposed
to high levels of
stress show
unusual patterns of cortisol production.27 Foster children exhibited unusually decreased or elevated levels of cortisol compared
to children reared by their biological parents.28 Such findings are consistent with the literature, which points
to the importance of the parent - child relationship in buffering the
stress responses of children.