Early deprivation and home basal cortisol levels: a study of internationally adopted children

Abstract

Animal studies reveal that early deprivation impairs regulation of the hypothalamic-pituitary-adrenocortical (HPA) axis, potentially increasing vulnerability to stressors throughout life. To examine early deprivation effects on basal HPA axis activity in humans, basal cortisol levels were examined in 164 internationally adopted children who had experienced varying degrees of preadoption deprivation. Duration of institutional care, age at adoption, and parent ratings of preadoption neglect indexed a latent factor of Deprived Care. Adoption measures of height and weight standardized to World Health Organisation norms indexed a latent factor of Growth Delay that was viewed as another reflection of deprivation. Cortisol samples were collected 3.3-11.6 years postadoption (Md = 7.3 years) at home on 3 days approximately 30 min after wakeup and before bedtime. Both early a.m. levels and the decrease in cortisol across the day were examined. A structural equation model revealed that preadoption Deprived Care predicted Growth Delay at adoption and Growth Delay predicted higher morning cortisol levels and a larger diurnal cortisol decrease.

Figure 1

The full structural equation model with unstandardized path coefficients. The control variables gender, parent education, and family income are not depicted for clarity of presentation. The control variables have paths pointing to all of the latent variables in the figure except a.m. cortisol and p.m. cortisol. Deprived Care, deprived care with indicators; Inst Duration, duration of institutional care; Age Adoption, age (months) child came into adoptive parents’ care; Neglect/Abuse, parent-rated neglect and abuse; Growth Delay, growth delay at adoption with indicators: Z Height, standardized height for age at adoption (reverse scored), Z Weight, standardized weight for height at adoption. Initial Status, predicted a.m. cortisol; Delta, latent difference score (p.m. cortisol – a.m. cortisol). *p < .05, **p < .01, ***p < .001.

Figure 2

The a.m. and p.m. cortisol levels in micrograms per deciliter (μg/dl) for children in the lowest (smallest) and highest (biggest) quartiles of standardized height for age at adoption. Error bars reflect the standard error of the mean.