What is Allostatic Load and Its Implications on Health

As the research on recovery processes implies, the long-term effects of stress on the body are of great importance when understanding the mechanisms by which physiological changes response to stress may promote illness.

The initial response of the body to stressful circumstances may be arousal, but over time this response may give way to exhaustion, leading to cumulative damage to the organism. Building these ideas, researchers developed the concept of allostatic load. Allostatic load specifically refers to a composite index of indicators of cumulative strain on multiple organs and tissues which accumulates via the wear and tear associated with acute shifts in physiologic activity in response to negative stimuli

This concept refers to the fact that physiological systems within the body fluctuate to meet demands from stress, a state called allostasis. Over time, allostatic load builds up, which is defined as the physiological costs of chrnic exposure to fluctuating or heightened neural or neuroendocrine response that results from repeated or chronic stress?

This buildup of allostatic load-that is, the long-term cost of chronic or repeated stress-can be assessed by a number of indicators. These include decreases in cell-mediated immunity, the inability to shut off cortisol in response to stress, lowered heart rate variability, elevated epinephrine levels, a high waist-to -hip ratio, volume of the hippocampus (which is believed to decreases with repeated stimulation of the HPA), problems with memory (an indirect measure of hippocampal functioning), high plasma fibrinogen, and elevated blood pressure. Many of these changes occur normally with age, so to the extent that they occur early, allostatic may be thought of as accelerated aging of the organism in response to stress. Over time, this kind of wear ad tear can lead to illness. These effects may be exacerbated by the poor health habits practices by people under chronic stress. The damage due to chronic or repeated stress is only made worse if people also cope with stress via a higher fat diet, less frequent exercise, and smoking, all of which stress can encourage.

The physiology of stress and , in particular, the recent research on the cumulative adverse effects of stress are important because they suggest the pathways by which stress exerts adverse effects on the body, ultimately contributing to the likelihood of disease. The relationship of stress, both short and long term, to both acute disorders such as infection, and chronic disease is now so well established that stress is implicated in most disease, either in their etiology, their course, or both. Sufficient to say, stress is one of the major risk factors for disease that humans encounter.
Reference: http://encyclopedia.tfd.com/Allostatic+load