Allostatic load

Allostatic load is 'the wear and tear on the body' which accumulates as an individual is exposed to repeated or chronic stress. The term was coined by McEwen and Stellar in 1993. It represents the physiological consequences of chronic exposure to fluctuating or heightened neural or neuroendocrine response which results from repeated or prolonged chronic stress.Type 1 allostatic load occurs when energy demand exceeds supply, resulting in activation of the emergency life history stage. This serves to direct the animal away from normal life history stages into a survival mode that decreases allostatic load and regains positive energy balance. The normal life cycle can be resumed when the perturbation has passed. Typical situations ending up in type 1 allostasis are starvation, hibernation and critical illness. Of note, the life-threatening consequences of critical illness may be both cause and consequences of allostatic load.Type 2 allostatic load results from sufficient or even excess energy consumption being accompanied by social conflict or other types of social dysfunction. The latter is the case in human society and certain situations affecting animals in captivity. In all cases, secretion of glucocorticosteroids and activity of other mediators of allostasis such as the autonomic nervous system, CNS neurotransmitters, and inflammatory cytokines wax and wane with allostatic load. If allostatic load is chronically high, then pathologies may develop. Type 2 allostatic overload does not trigger an escape response, and can only be counteracted through learning and changes in the social structure. Allostatic load is 'the wear and tear on the body' which accumulates as an individual is exposed to repeated or chronic stress. The term was coined by McEwen and Stellar in 1993. It represents the physiological consequences of chronic exposure to fluctuating or heightened neural or neuroendocrine response which results from repeated or prolonged chronic stress. The term allostatic load is 'the wear and tear on the body' which accumulates as an individual is exposed to repeated or chronic stress. It was coined by McEwen and Stellar in 1993. The term is part of the regulatory model of allostasis, where the predictive regulation or stabilisation of internal sensations in response to stimuli is ascribed to the brain. Allostasis involves the regulation of homeostasis in the body to decrease physiological consequences on the body. Predictive regulation refers to the brain's ability to anticipate needs and prepare to fulfill them before they arise. Part of efficient regulation is the reduction of uncertainty. Humans naturally do not like feeling as if surprise is inevitable. Because of this, we constantly strive to reduce the uncertainty of future outcomes, and allostasis helps us do this by anticipating needs and planning how to satisfy them ahead of time. But it takes a considerable amount of the brain's energy to do this, and if it fails to resolve the uncertainty, the situation may become chronic and result in the accumulation of allostatic load. The concept of allostatic load provides that 'the neuroendocrine, cardiovascular, neuroenergetic, and emotional responses become persistently activated so that blood flow turbulences in the coronary and cerebral arteries, high blood pressure, atherogenesis, cognitive dysfunction and depressed mood accelerate disease progression.' All long-standing effects of continuously activated stress responses are referred to as allostatic load. Allostatic load can result in permanently altered brain architecture and systemic pathophysiology. Allostatic load minimizes an organism's ability to cope with and reduce uncertainty in the future.