Allostasis , Homeostasis and the Cost of Physiological Adaptation

Quite well established are the concepts of homeostasis and balance as well as biological and behavioral adaptation to maintain homeostasis. They may be traced to antiquity, both in the Western and Eastern traditions. Homeostatic concepts emphasize the interaction between brain, body, and environment. Concepts of homeostasis and adaptation have been a driving force for substantive research and theoretical discourse in the modern era, since Bernard (1865), Pavlov (1897), Cannon (1915), Selye (1956), and their disciples. The current book illustrates the state of the art of the evolution of the concept of homeostasis to allostasis—which delineates longerterm biological and behavioral adaptation mechanisms that maintain internal viability amid the changing conditions of the external world as well as internal body changes. The coordinating regulatory processes of the central nervous system play a major role in the homeostatic and allostatic mechanisms. Therefore, the concept of allostasis is important in the attempts to understand the interactions between living organisms and their environment and between the mind and the body. An important aspect of allostasis and adaptation is the effort required to adapt and maintain adaptation over time—the price paid by the organism in its efforts to survive and the wear and tear evolving over time, in other words, ‘‘the allostatic load.’’ In Allostasis, Homeostasis and the Costs of Physiologic Adaptation, editor Jay Schulkin of Georgetown University assembled a group of distinguished investigators and thinkers in this emerging field, who provide a wellrounded intriguing picture for the noninitiated readers and food for thought for the quasi-experts. The history, evolution, and principles of allostasis are reviewed by one of the founding fathers of the concept, Peter Sterling, in Chapter 1. Sterling combines social observations with physiology into a coherent dynamic structure. He stresses the importance of rate of adaptation, multilevel, multidimensional organizations, and the therapeutic implications of allostatic concepts. The role of stress and adaptation in allostasis and allostatic load is reviewed in Chapter 2 by Bruce McEwen, who also illuminates the multiple aspects of the adaptation process and its disruption. The theme is further developed in Chapter 3 by David Goldstein, who merges the homeostatic theory with the concepts of allostasis, and in Chapter 4 by Burton Singer and colleagues, who illustrate the concepts with actual studies and methods for their analyses and measurements. This chapter is especially intriguing in the attempt to quantify social and physiological allostatic loads and risks over time. It moves the readers from theory to real-world applications. The application of allostatic load theory to specific disorders is the subject of several chapters in the book. In Chapter 5, George Koob and Michael LeMoal review the role of adaptational mechanisms and allostasis in drug addiction, and in Chapter 6, Jeffrey Rosen and Jay Schulkin examine the pathology of anxiety and depression in a similar framework. Both emphasize the role of the hypothalamic– pituitary–adrenal (HPA) system and the regulation and interactions of catecholamines in the mechanism of stress response. A chronobiological perspective is introduced in Chapter 7 by Ziad Boulos and Alan Rosenwasser, who describe regulatory and disruptive mechanisms ranging from diurnal and seasonal rhythms, sleep, menstrual cycle and reproduction, to long-term life-cycle maturation and aging. Shift-work provides for an excellent example of disruption in the circadian pattern, its load, and consequences, which are described later in the chapter. The multiple processes and systems involved in the disruption are eloquently analyzed. The longitudinal approach to allostatic load is further emphasized in Chapter 8 by John Wingfield, who examines the concept and its association with life cycles. Described from several complementary viewpoints are the various aspects of neuroendocrine systems in the maintenance of homeostasis and allowed adaptations and adjustments. This edited, multiple authors’ book provides a kaleidoscopic view of allostasis and adaptation. The same basic concept is reviewed by different authors from their own specific perspectives. Together they challenge the readers to view life as a dynamic process of a holistic interaction between the