Allostatic load
Allostatic load means "the wear and tear on the body" which accumulates as an individual is exposed to repeated or chronic stress.
[2] The term is part of the regulatory model of allostasis, where the predictive regulation or stabilization of internal sensations in response to stimuli is ascribed to the brain.
Humans are naturally averse to surprise; because of this, they constantly strive to reduce the uncertainty of future outcomes, and allostasis enables this by anticipating needs and planning how to satisfy them ahead of time.
[6] 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.
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.
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.
[10][13] Allostatic load is generally measured through a composite index of indicators of cumulative strain on several organs and tissues, primarily biomarkers associated with the neuroendocrine, cardiovascular, immune, and metabolic systems.
Allostatic load is not unique to humans and may be used to evaluate the physiological effects of chronic or frequent stress in non-human primates as well.
[5] The R package pscore[17] provides functions for simplified and automated calculation and statistical evaluation of physiological components of the metabolic syndrome symptom score (MSSS) and allostatic load.
[18] Allostasis and allostatic load are related to the amount of health-promoting and health-damaging behaviors like for example cigarette smoking, consumption of alcohol, poor diet, and physical inactivity.
[21][22] When the cumulation of stressful experiences leads to chronic exposure to fluctuations in neural or neuroendocrine responses, which surpass the individual's coping ability, the result is considered to be an allostatic load.
[26] The long-term impact of childhood adversity (e.g., abuse, neglect) has been shown to have lasting effects, including the increased risk for allostatic load in adulthood.
[29] Extended activation of the hypothalamic-pituitary-adrenal axis (HPA), as well as the autonomic nervous system, can lead to negative impacts on biological health.
[26] The human body regulates itself to maintain a status of homeostasis by utilizing allostatic mechanisms, but when there are extended stress responses that continue past the duration of the stressor's termination, it leads to the failure of these systems.
Several studies documented a strong association of allostatic load to the incidence of coronary heart disease,[30] to surrogate markers of cardiovascular health[31][32][33][34] and to hard endpoints, including cause-specific and all-cause mortality.
[46] Interventions can include encouraging sleep quality and quantity, social support, self-esteem and wellbeing, improving diet, avoiding alcohol or drug consumption, and participating in physical activity.
Protective factors could, at various times of an individual's life span, be implemented to reduce stress and, in the long run, eliminate the onset of allostatic load.
[4] Protective factors include parental bonding, education, social support, healthy workplaces, a sense of meaning towards life and choices being made,[48] and positive feelings in general.
