Allostatic Load: Stress Upon Stress

Chronic stress is a potentially lethal condition that is characterized by long duration and effect accumulation. Humans respond to stressors such as physical or perceived danger, an infection, or a crowded and noisy environment, by initiating a complex biopsychosocial adaptation and coping response. This response is initiated by the sympathetic nervous system and leads to release of excitatory stress hormones (the catecholamines) and glucocorticoids from the adrenal cortex (the well-known adrenaline rush).

The objective of this rapid physical mobilization of the body’s resources is to engage with the stressor, resolve it and return to a more normal state of alertness. Regaining normal arousal levels through a response and adaptation to the stressor is called allostasis. A highly stressed state is meant to be temporary and to subside naturally when the challenge has passed.

There is never a shortage of situations that trigger the stress reaction, at work or at home. All of us face the not too uncommon challenge of having to cope with more than one stressor at once or a series of stressors that happen within a relative short time. Most individuals can cope with this type of demands and are able to regain allostasis once the stressor or stressors have been taken care of or have taken care of themselves.

When individuals are not able to cope effectively with the stressor and cannot regain allostasis, this creates an accumulation of allostatic load. In this situation, there is an incomplete return to the normal condition and a regaining of physical and emotional stability. In fact, a state of stress at relatively high levels becomes the “new normal.” Over many weeks, months, or even years, this exposure to elevated levels of stress hormones can produce allostatic overload, with predictably serious health consequences.

Type 1 Allostatic Load

If the physical and emotional energy required to meet the demands created by one’s cumulative allostatic load routinely exceeds the energy intake and what can be mobilized from one’s own resources, type 1 allostatic overload occurs.

Allostatic overload type 1 is characterized by a significant increases in the circulation of glucocorticoids in the bloodstream (and other hormones that regulate allostasis), which triggers physiological and behavioral changes. These changes refocus the individual from functioning at normal levels of stress in daily routines into a high-stress high-alert survival mode.

Type 2 Allostatic Load

If energy demands are not exceeded and the individual continues to take in or store as much or even more energy than he/she needs—perhaps as a result of stress-related food consumption, choice of a fat-rich diet, or metabolic imbalances (prediabetic state) that favor fat accumulation—then type 2 allostatic overload occurs.

Allostatic overload type 2 causes lesser but higher than normal levels of glucocorticoids (and other hormones that regulate allostasis), which do not trigger physiological and behavioral responses, in such a way the individual remains stuck in a situation of high allostatic load without resolution.

Allostatic Load and Its Consequences

Elderly people who have had a lifetime of sustained economic hardship can have a more rapid decline of physical and mental functioning.  Hypertension is often an indicator of job stress, particularly in factory workers, in other workers with repetitive jobs and time pressures, and in workers whose jobs were unstable due to financial and market conditions.

In certain societies, conflict and social instability have been found to increase illness and mortality. For example, cardiovascular disease was found to be a major contributor to the almost 40% increase in the death rate among Russian males in the social upheaval which followed the fall of Communism. High blood pressure causes atherosclerosis as well as increased risk for heart attacks.

Abdominal obesity is another stress-linked change, which is often a precursor to more serious illness such as diabetes. The immune system is also a likely target of psychosocial stress, increasing vulnerability to the common cold and other more serious infections.

When Stress Becomes Trauma

aaHiroshige_TakanawaThere have been considerable advances in the last few years of our understanding of stress, its origin, its antecedents and the course of its manifestations. Significant progress has also been made in understanding what can help reduce its effects on functioning and mood. In spite of the barrage of advertising that promotes such “remedies” as prescription opioids and “benzos” and the ever-present allure of alcohol or marijuana, many people now know that exercise can work just the same, if not better, in reducing stress and anxiety.

There are certain stressors, however, that produce effects that go beyond and cross into a different domain, that of traumatic stress. Recent research places posttraumatic stress disorder (PTSD) within a theory of pathological anxiety, whereby the individual becomes vulnerable in two very important ways.

The first vulnerability precedes the traumatic stressor and is an innate, and therefore genetic, biological predisposition of the individual toward experiencing intense, negative emotions that can easily escalate into panic or degenerate into depression. This biological vulnerability can have many effects, chief among which is the inability to correctly assess the difference between true and false alarms and the subsequent inability to correctly decide on the most appropriate response between fight, flight or freeze. A true state of alarm arousal is the normal and most appropriate reaction to a truly threatening event or situation, i.e. what most people would find dangerous or risky. A falsely perceived state of alarm is one that causes a sudden and involuntary mobilization of the body and the mind’s defenses, in the presence of a situation or event that is objectively non threatening but is assessed as such by the individual who is genetically predisposed to an intense alarm reaction.

The second vulnerability is psychological in nature. Individuals who develop this sensitivity report a greatly reduced sense of control over events and situations. They tend to approach the present and imagine the future with anxious apprehension. Their mood is often characterized by an anxious state of exaggerated vigilance, whereby it is inherently hard to relax and enjoy life. Cognitively, they expect and anticipate the appearance of various threats, external and internal, with an attending constellation of negative emotions (fear, obsession, panic). This complex system of cognitive and emotional arousal usually promotes avoidance and triggers a near-constant state of worry.

When applied to traumatic stress, these vulnerabilities magnify the experience of a traumatic event and trigger a significantly more severe state of alarm at the time of the trauma. It is well known fact that some individuals appear able to remain relatively calm in the face of traumatic events, while others (who are more likely to have bio-psychological vulnerabilities to intense stressors) seem to quickly “fall apart” and be seemingly “destroyed” by the circumstance.

When the intense trauma passes, these individuals remain in a state of arousal that continues to trigger alarms in response to internal and external stimuli associated with the trauma, and their
initial response to it. For example, a sudden noise may trigger the stimulus associated with a bomb blast, or a burst of anger by another may trigger a stimulus associated with physical abuse. These learned responses to real or perceived threats produce a state of anxious apprehension which, in PTSD, includes the re-experiencing of emotions. This near-continuous state of alarm may, in time, be mitigated by coping mechanisms which generally consist of an individual’s efforts at avoiding the triggers of the learned alarms and the strong emotions associated with them. Intense avoidance of any stimulation that may results in a re-experience of the traumatic events and its associated emotions can eventually developed into a state of emotional numbing, where even those stimuli that should provoke a reaction do not.