Foster children's diurnal cortisol patterns across early childhood and associations with social-cogitive and behavior regulation outcomes at early school age

The present longitudinal study examined diurnal cortisol patterning over time among 65 children, 41 children with histories of foster care and 24 comparison children, in relation to social-cognitive and behavior regulation outcomes. Diurnal cortisol patterns were assessed via assay of wake-up and bedtime saliva samples collected over 2-3 consecutive days at two developmental timepoints: infancy/toddlerhood (Time 1) and early school age (Time 2). Social-cognitive and behavior regulation outcomes were assessed at Time 2. Structural equation models of latent difference scores revealed that adopted and comparison children's wake-up cortisol values did not differ at Time 1 or 2, but adopted children showed less of a decrease in cortisol across the day at Time 1 relative to comparison children. Participation in an early intervention program, attachment disorganization, and foster care placement instability were also examined as predictors of diurnal cortisol patterns. With regard to social-cognitive outcomes, steeper diurnal change in cortisol at Time 2 was associated with higher cognitive flexibility and theory of mind abilities, when controlling for several demographic variables. These results could inform early intervention programs by providing a better understanding of risk factors that predict flatter diurnal cortisol patterns, and the specific outcomes associated with flatter diurnal cortisol patterns.