Allostatic load

Allostatic load is the cumulative physiological cost of adapting to chronic stressors, representing wear and tear on regulatory systems that maintain homeostasis through continuous adjustment—a process termed allostasis. The concept was developed by Bruce McEwen and Eliot Stellar in 1993 and operationalised in epidemiology as a composite score across neuroendocrine (e.g. cortisol, DHEA-S), cardiovascular, metabolic, and immune biomarkers. Higher allostatic load predicts all-cause mortality, cardiovascular disease, cognitive decline, and accelerated biological ageing, and mediates socioeconomic disparities in health. In longevity research, it provides a framework for understanding how cumulative psychosocial and environmental stress translates into measurable organ-system dysregulation.