Unraveling current and future adolescent depressive symptoms: The role of stress reactivity across physiological systems.

Neurobiological processes are highlighted in animal and theoretical models of the development of depression, but there is mixed empirical evidence about associations between stress physiology and depressive symptoms. Adolescence has been highlighted as a period during which coordination across physiological stress response systems may be particularly important. However, most studies have focused on depressive symptoms and physiological reactivity in isolated systems. The goal of this study was to examine associations of hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS; i.e., sympathetic and parasympathetic nervous system [SNS and PNS, respectively]) reactivity with depressive systems, as well as the interrelatedness of reactivity across systems. Participants were adolescents (n = 153, 10-17 years) from diverse backgrounds, recruited from the community. Adolescents experienced a stressor, during which cortisol (HPA axis), skin conductance level (SCL; SNS), and respiratory sinus arrhythmia (RSA; PNS) were measured; youth also reported depressive symptoms. Some youth (n = 60) reported depressive symptoms again 1 year later as part of another study. Results from latent growth analysis embedded in a structural equation model (SEM) indicated that concurrent depressive symptoms were predicted by an interaction between cortisol reactivity and baseline RSA levels, with fewer symptoms for adolescents who had lower baseline RSA and greater cortisol reactivity. Controlling for concurrent depressive symptoms, prolonged cortisol recovery (above and beyond cortisol or ANS reactivity), was related to prospective depressive symptoms. Results support and extend theoretical arguments about the role of dysregulated stress physiology in the development of depressive symptoms, and the importance of multisystem approaches to understanding the role of stress physiology in risk and resilience. (PsycINFO Database Record (c) 2018 APA, all rights reserved).