Early calibration of the HPA axis by maternal psychopathology.

Given the central role of stress-responsive neurophysiology in mental and physical health, it is important to understand how particular patterns of stress responsivity may become entrained by the early caregiving environment. In this study we investigated links between maternal depression and anxiety symptom profiles and within-infant development of hypothalamic-pituitary-adrenal (HPA) axis responses from 6 to 18 months of life. Associations with infant cognitive and social-emotional development were also tested to gauge the adjustment implications of HPA response trajectories. Mothers from a low-income community sample reported their symptoms at 3, 6, 12, and 18 months postnatal, and infants engaged in interpersonal stress tasks at 6, 12, and 18 months. Four saliva samples were taken at each time to assess cortisol responses, and a developmental screener at 18 months provided an index of infant adjustment. Multilevel modeling results revealed an association between maternal symptoms and infant HPA axis sensitization-i.e., a higher cortisol reactivity slope that increased over time. In particular, early (3-month) depression symptoms among mothers who had crossed a diagnostic threshold for major depressive disorder predicted this pattern of response, which in turn related to poorer infant developmental outcomes. Results are considered in terms of adaptive calibration of stress response systems, which may come at a cost to individual psychosocial functioning.