Theory suggests that early experiences may calibrate the threshold activity of the hypothalamus-pituitary-adrenal axis in childhood. Particularly challenging or particularly supportive environments are posited to manifest in heightened physiological sensitivity to context. Using longitudinal data from the Family Life Project (N = 1,292), we tested whether links between maternal sensitivity and hypothalamus-pituitary-adrenal axis activity aligned with these predictions. Specifically, we tested whether the magnitude of the within-person relation between maternal sensitivity and children's cortisol levels, a proxy for physiological sensitivity to context, was especially pronounced for children who typically experienced particularly low or high levels of maternal sensitivity over time. Our results were consistent with these hypotheses. Between children, lower levels of mean maternal sensitivity (7-24 months) were associated with higher mean cortisol levels across this period (measured as a basal sample collected at each visit). However, the magnitude and direction of the within-person relation was contingent on children's average levels of maternal sensitivity over time. Increases in maternal sensitivity were associated with contemporaneous cortisol decreases for children with typically low-sensitive mothers, whereas sensitivity increases were associated with cortisol increases for children with typically high-sensitive mothers. No within-child effects were evident at moderate levels of maternal sensitivity.
Bibliographical noteFunding Information:
The Family Life Project Phase I Key Investigators include Lynne Vernon-Feagans, University of North Carolina; Martha Cox, University of North Carolina; Clancy Blair, Pennsylvania State University; Peg Burchinal, University of North Carolina; Linda Burton, Duke University; Keith Crnic, Arizona State University; Ann Crouter, Pennsylvania State University; Patricia Garrett-Peters, University of North Carolina; Mark Greenberg, Pennsylvania State University; Stephanie Lanza, Pennsylvania State University; Roger Mills-Koonce, University of North Carolina; Emily Werner, Pennsylvania State University; and Michael Willoughby, University of North Carolina. This research was supported by grants from the National Institute of Child Health and Human Development (R01 HD51502 and P01 HD39667). Cofunding was provided by the National Institute of Drug Abuse, NIH Office of Minority Health, NIH Office of the Director, National Center on Minority Health and Health Disparities, and the Office of Behavioral and Social Sciences Research. We express our sincere gratitude to all of the families, children, and teachers who participated in this research and to the Family Life Project research assistants for their hard work and dedication. Douglas A. Granger is Founder and Chief Strategy and Scientific Advisor at Salimetrics LLC (State College, PA) and Salivabio LLC (Baltimore, MD). Dr. Granger's relationships with these entities are managed by the policies of the Conflict of Interest Committee at the Johns Hopkins University and the Office of Research Integrity and Assurance at Arizona State University. The other authors have no conflicts of interest to declare.
Copyright © Cambridge University Press 2016.