Influence of early life stress on later hypothalamic-pituitary-adrenal axis functioning and its covariation with mental health symptoms: a study of the allostatic process from childhood into adolescence

Abstract

The hypothalamic-pituitary-adrenal (HPA) axis is a primary mechanism in the allostatic process through which early life stress (ELS) contributes to disease. Studies of the influence of ELS on children's HPA axis functioning have yielded inconsistent findings. To address this issue, the present study considers multiple types of ELS (maternal depression, paternal depression, and family expressed anger), mental health symptoms, and two components of HPA functioning (traitlike and epoch-specific activity) in a long-term prospective community study of 357 children. ELS was assessed during the infancy and preschool periods; mental health symptoms and cortisol were assessed at child ages 9, 11, 13, and 15 years. A three-level hierarchical linear model addressed questions regarding the influences of ELS on HPA functioning and its covariation with mental health symptoms. ELS influenced traitlike cortisol level and slope, with both hyper- and hypoarousal evident depending on type of ELS. Further, type(s) of ELS influenced covariation of epoch-specific HPA functioning and mental health symptoms, with a tighter coupling of HPA alterations with symptom severity among children exposed previously to ELS. Results highlight the importance of examining multiple types of ELS and dynamic HPA functioning in order to capture the allostatic process unfolding across the transition into adolescence.

Figure 1

Overall group comparison of and developmental changes in trait-like cortisol level and diurnal rhythm by early life exposure to maternal depression and/or family expressed anger. Because the developmental change was linear, the age 11 and age 13 effects are omitted and only age 9 (grey) and age 15 (black) are shown.

Figure 2

Overall group comparison at age 15 of epoch-specific cortisol level and diurnal rhythm by concurrent mental health symptom severity and early life exposure to maternal depression and/or family anger. For clarity of presentation, comparison lines for group effects at average levels of mental health symptom severity are omitted. Results did not differ by age, so age 15 is shown as a representative example.

Figure 3

Overall group comparison at age 15 of epoch-specific cortisol level and diurnal rhythm by concurrent mental health symptom severity and early life exposure to paternal depression and/or family expressed anger. For clarity of presentation, comparison lines for group effects at average levels of mental health symptom severity are omitted. Results did not differ by age, so age 15 is shown as a representative example.

Figure 4

Illustration of the co-variation in trait-like morning cortisol levels and mental health symptom severity over time by early life exposure to maternal depression and/or family expressed anger. Cortisol levels at average symptom severity are shown (in grey) for comparison purposes. The illustrative lines (in black) show cortisol levels for the high ELS groups when †symptom severity is set at 2 SD below the mean (ages 9 and 13) or ‡symptom severity is set at 2 SD above the mean (ages 11 and 15).