The concept of allostasis: A new paradigm at the frontier between health and disease

Authors

Johannes W. Dietrich

Abstract

Origin and evolution of life are marked by increasing independence of the developing organisms from physical and chemical boundary conditions. Being characteristic of living systems this form of liberty demands processes of information processing, self-organisation and self-regulation. The discovery of these biological foundations hallmarked the transition to modern life sciences in the 19th and 20th centuries. A key element of this process was the formulation of the principle of homeostasis by Walter B. Cannon.

Despite its fundamental role in the understanding of physiology, the concept of homeostasis is unable to explain all phenomena of life and all kinds of disease. Broadening the concept of homeostasis by the introduction of adaptive and predictive (“allostatic”) modes of control recent research helped to solve some intrinsic problems of the homeostatic theory. Thereby, the theory of allostasis extends both the theories of stress and of homeostasis. 

Allostasis ensures “stability through change” in situations of strain and stress. If in allostatic mode a feedback control system is able to change both its set point and its parameters to approach a state vector that is more suitable for survival. An allostatic response involves the activation of actuator variables that is referred to as allostatic state. Although allostasis is basically beneficial for viability it also exposes the organism to some kind of strain, referred to as allostatic load. If ongoing or being excessive, allostatic load may be life-threatening on its own terms. In this situation, it is referred to as allostatic overload.

The idea of allostasis helped to lift our understanding of a broad range of diseases and certain bio-psycho-social situations to a new level. Typical examples include fever, starvation, type 2 diabetes, hypertension, thyroid disorders and psychosomatic diseases. Being both comprehensive and simple this new theory provides an elegant description of pathophysiological processes that lead to complex diseases. In addition, the advent of panels for allostatic load facilitates differential diagnosis at the verge between health and disease.

References

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