Lifetime stressors, hair cortisol, and executive function: Age-related associations in childhood.

Extant research is mixed regarding the relations among lifetime exposure to stressors, adrenocortical activity, and executive function (EF), particularly in children. Aggregate measures of adrenocortical activity like hair cortisol concentration (HCC), timing of stress exposure, and age at assessment may clarify these associations. This cross-sectional study examined the association among parent-reported exposure to stressors, hair cortisol concentration (HCC), and children's EF via a tablet task in a community sample (n = 318, 52.5% female) of children across a wide age range (4-13 years, M = 9.4, SD = 2.3). Path analyses revealed that parent-reported child lifetime exposure to stressors, but not past-year stressful life events, negatively predicted HCC. There was also a marginally significant moderation by age such that HCC was associated negatively with EF for younger children (age < 9.7 years) but not older children. HCC did not significantly mediate the association between lifetime exposure to stressors and EF. Findings are consistent with the proposition that chronically high cortisol production has a neurotoxic effect on brain regions supporting EF. However, lifetime exposure to stressors predicted relatively lower cumulative cortisol production, consistent with a stress inoculation effect in this normative-risk sample.