Income, cumulative risk, and longitudinal profiles of hypothalamic-pituitary-adrenal axis activity in preschool-age children.

Environmental risk predicts disrupted basal cortisol levels in preschool children. However, little is known about the stability or variability of diurnal cortisol morning levels or slope patterns over time in young children. This study used latent profile analysis to identify patterns of the hypothalamic-pituitary-adrenal axis activity during the preschool period. Using a community sample (N = 306), this study measured income, cumulative risk, and children's diurnal cortisol (morning level and slope) four times across 2.5 years, starting when children were 36 months old. Latent profile analysis profiles indicated that there were predominantly stable patterns of diurnal cortisol level and slope over time and that these patterns were predicted by income and cumulative risk. In addition, there were curvilinear relations of income and cumulative risk to profiles of low morning cortisol level and flattened diurnal slope across time, suggesting that both lower and higher levels of income and cumulative risk were associated with a stress-sensitive physiological system. Overall, this study provides initial evidence for the role of environmental risk in predicting lower, flattened basal cortisol patterns that remain stable over time.