Psychoneuroendocrinology (2015) 52, 311—323 Available online at www.sciencedirect.com ScienceDirect j ourna l h om epa ge : www.elsevier.com/locate/psyneuen The developmental course of salivary alpha-amylase and cortisol from 12 to 36 months: Relations with early poverty and later behavior problems Ashley L. Hill-Soderlund a,* , Steven J. Holochwost b , Michael T. Willoughby c , Douglas A. Granger d,e , Jean-Louis Gariépy f , W. Roger Mills-Koonce g , Martha J. Cox f a Center for Developmental Science, University of North Carolina at Chapel Hill, USA b Department of Psychology, Georgetown University, USA c Frank Porter Graham Child Development Institute, University of North Carolina at Chapel Hill, USA d Institute for Interdisciplinary Salivary Bioscience Research, Arizona State University, USA e Johns Hopkins University School of Nursing, Johns Hopkins University Bloomberg School of Public Health, USA f Department of Psychology, University of North Carolina at Chapel Hill, USA g Department of Human Development and Family Studies, University of North Carolina at Greensboro, USA Received 4 April 2014; received in revised form 14 August 2014; accepted 25 August 2014 KEYWORDS Salivary alpha-amylase (sAA); Cortisol; Poverty; Externalizing problems; Internalizing problems; Development; Early childhood Summary This study examined the development of baseline autonomic nervous system (ANS) and hypothalamic—pituitary—adrenal (HPA) physiological activity from 12 to 36 months as well as antecedents (poverty) and consequents (behavior problems) of individual differences in phys- iological development. Children (N = 179; 50% poor; 56% African American; 52% male) provided saliva samples at 12, 18, 24, 30, and 36 months of age. Latent growth curve models indicated that nonlinear change was evident for both sAA and cortisol, with sAA increasing and cortisol decreasing with age. Children residing in poor households exhibited lower initial levels of sAA, but not cortisol. African-American children showed slightly smaller decreases in cortisol over time. Initial levels of sAA predicted higher levels of internalizing behaviors at 36 months and both initial levels of and total change in sAA predicted higher levels of externalizing behaviors at 36 months. There was no evidence that sAA or cortisol mediated the relationship between poverty and later behavior problems. © 2014 Elsevier Ltd. All rights reserved. ∗ Corresponding author. Tel.: +1 9199620333. E-mail address: soderlund.ashley@gmail.com (A.L. Hill-Soderlund). http://dx.doi.org/10.1016/j.psyneuen.2014.08.011 0306-4530/© 2014 Elsevier Ltd. All rights reserved.