Ilia N. Karatoreos & and Bruce S. McEwen

Background: Adaptation is key to survival. An organism must adapt to environmental challenges in order to be able to thrive in the environment in which they find themselves. Resilience can be thought of as a measure of the ability of an organism to adapt, and to withstand challenges to its stability. In higher animals, the brain is a key player in this process of adaptation and resilience, and through a process known as “allostasis” can obtain “stability through change”; protecting homeostasis in the face of stressors in the environment. Mediators of allostasis, such as glucocorticoids, can cause changes in the structure and function of neural circuits, clearly impacting behavior. How developmental stage interacts with stress and leads to long-lasting changes is a key question addressed in this review. Scope and Methods: We discuss the concept of allostasis, its role in resilience, the neural and physiological systems mediating these responses, the modulatory role of development, and the consequences for adult functioning. We present this in the context of mediators the brain and body engage to protect against threats to homeostasis. The review has been informed by comprehensive searches on PubMed and Scopus through November 2012. Findings: Stressors in the environment can have long lasting effects on development, depending upon the stage of life at which they are experienced. As such, adverse childhood experiences can alter resilience of individuals, making it more difficult for them to respond normally to adverse situations in adulthood, but the brain maintains the capacity to reenter a more plastic state where such effects can be mitigated. Conclusions: The brain regulates responses that allow for adaptation to challenges in the environment. The capacity of the brain and body to withstand challenges to stability can be considered as “resilience”. While adverse childhood experiences can have long-term negative consequences, under the right circumstances, the brain can re-enter plastic states, and negative outcomes may be mitigated, even later in life. Keywords: Allostasis, hormones, neurobiology, aging, brain development.

karatsoreos2013.pdf

Gustavo E. Tafeta y Renato Bernardini

Abstract Objective: The goal of this report is to develop a comprehensive model, which integrates psychosocial and neurobiological aspects, for better understanding the link between chronic stress and mood disorders. Method: A selective review of the relevant bibliography was conducted. The significant data were integrated with clinical and preclinical findings, particularly focusing on the effect of the hypothalamo – pituitary – adrenal (HPA) activity on the serotonergic neurotransmission in the CNS. Results: The reviewed data shows that chronic application of stress responses may lead to alterations in the regulation of the HPA system, and the resulting hypercortisolism may be reflected in various psychoneuroendocrinological processes, such as the observed in the serotonergic system, which was implicated in the origin and development of depression. Conclusions: The analysis of the interactions between the different components of this process, suggests that normalization of the HPA system, either directly through psychopharmacologic strategies, or indirectly through psychotherapeutic approaches oriented to improve the cognitive appraisal of stressful situations, may provide us with more effective diagnostic, preventive, and therapeutic methods in the treatment of widespread anxiety and mood disorders. D 2003 Elsevier Inc. All rights reserved.

Keywords: Depression; Psychoneuroendocrinology; Stress.

tafet2003.pdf