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parents who had no previous record of abuse or maltreatment.
Children who had experienced more severe emotional, phys-
ical and sexual maltreatment did indeed have abnormally high
morning cortisol levels. But scientists also found that children
who experienced more severe neglect had abnormally low morn-
ing cortisol levels. Different types of adversity, in other words,
had different impacts on the HPA system. But whether the adver-
sity took the form of an absence of stimulation or the presence of
negative, threatening stimulation, the effect was bad for normal
development.
“Low cortisol levels, particularly in the morning, had been linked
to externalizing disorders—things like delinquency and alcohol
use—whereas high cortisol levels have been linked to more anxiety
and depression,” and post-traumatic stress disorder, Bruce says.
Even so, Bruce and her colleagues noted that within both
groups, “some kids are doing really well, some kids are not do-
ing well.” This suggested other factors were also involved. And in
recent years, much of the research has focused on understandingcortisol levels, in the hopes of verifying this hypothesis. When
researchers began to compare their levels to that of children who
had not faced adversity, they found substantial differences. But
the results were difficult to interpret.
“There was growing evidence that there was an impact, but the
studies were contradictory,” says Jackie Bruce, a research scientist
at the Oregon Social Learning Center, an NIH-funded research
center in Eugene that studies child development. “Sometimes
people were finding kids with early adversity had low cortisol
and sometimes they were finding they had high cortisol.”
In 2009, Bruce and her colleagues demonstrated a possible expla-
nation for the discrepancies. Since morning cortisol levels play such
an important role in getting well-functioning individuals ready for
the day, they sought out a group of 117 maltreated 3- to 6-year-old
children transitioning into new foster care placements in the United
States. The researchers then trained the children’s caregivers to col-
lect saliva samples before breakfast. For comparison, they recruited a
control group of 60 low-income children living with their biologicaloften it’s partially because your parents are NOT INTERVENING.”