Allostatisk

Allostatisk is the Scandinavian-language adjective corresponding to allostatic. In English, the term is allostatic. Allostasis refers to the dynamic process by which the body maintains stability through change, adjusting physiological set-points across multiple systems to meet stressors and environmental demands. The concept, introduced by Sterling and Eyer in 1988, emphasizes that stability is achieved not by keeping variables constant, but by changing them adaptively.

Allostatic mechanisms involve the autonomic nervous system, the hypothalamic-pituitary-adrenal axis, immune, and metabolic processes; brain circuits including the prefrontal cortex, amygdala, and hippocampus regulate these responses. The system operates on different time scales, with rapid hormonal and autonomic changes during acute stress and slower metabolic adjustments during chronic exposure.

Allostatic load describes the cumulative burden on body systems from repeated or chronic stress and life events, leading to wear-and-tear and dysregulation. Excessive allostatic load is associated with higher risk for cardiovascular disease, metabolic syndrome, obesity, depression, and cognitive decline. Measurement often uses composite biomarker indices including cortisol, blood pressure, waist-hip ratio, C-reactive protein, and autonomic indicators; however, quantifying allostatic load remains methodologically challenging.

Allostasis and allostatic load are often contrasted with homeostasis, which emphasizes maintaining constancy around fixed set-points. Allostasis highlights context-dependent adjustments, energy cost, and trade-offs in achieving stability. Critics note the complexity and measurement difficulties, and ongoing work aims to refine models and practical applications.

In research and clinical contexts, allostatic concepts inform studies on stress, aging, mental health, and resilience, and guide approaches to reducing chronic stress and its physiological impact.