What Is Allostatic Load?

What Is Allostatic Load?

Allostatic load refers to the cumulative effects that chronic stress has on mental and physical health. More simply, it refers to the 'wear and tear' on the body that life events and environmental stressors create. When events occur that exceed an individual's capacity to cope, allostatic overload may occur.

Allostatic load was introduced by neuroendocrinologist Bruce McEwen and psychological psychologist Eliot Stellar in 1993. McEwen described allostatic load as the price people pay for adapting to stress. It is meant to objectively measure the biological consequences of prolonged stress.

When faced with stress, the body responds in a variety of ways to cope with the threat. Allostasis refers to how the body's physiological systems change in order to meet the demands of the environment. This ability to adapt is essential for survival.

While these processes serve an important role in helping us respond when we need to respond, they also come with a cost—the allostatic load. Researchers have described allostatic load as "the long-term result of failed adaptation or allostasis, resulting in pathology and chronic illness."

How Allostatic Load Works

The allostatic load model suggests that stress and its effects take a cumulative toll on the body. Stress leads to the fight or flight response, which triggers the release of hormones, including catecholamines and glucocorticoids. These serve an essential role in the short term by preparing the body to deal with the threat, maintaining homeostasis, and allowing the body to adapt.

Stress hormones, including cortisol and catecholamines, are essential for adaptation to manage acute challenges. At the same time, however, they also play a part in creating physiological changes that ultimately contribute to various physical effects, including negative effects on metabolic, immune, and cardiovascular processes. This can lead to increased blood sugar, inflammation, blood pressure, and other problems that pose health risks.

Signs of Allostatic Load

McEwen notes that stress is subjective, but that many of the things that create stress and have adverse health effects are simply aspects of daily life. Nevertheless, these daily hassles create stress that has cumulative and lasting consequences.

Primary mediators include:

• Dehydroepiandrosterone sulfate: Indicator of adrenal gland functioning
• Cortisol: A stress hormone that acts as a measure of the activity of the hypothalamic-pituitary-adrenal axis
• Epinephrine and norepinephrine: Hormone that provides information about the activity of the sympathetic nervous system

Secondary outcomes include:

• Systolic blood pressure and diastolic blood pressure: A risk factor for vascular disease that provides information about cardiovascular activity.  
• Waist–hip ratio: Provides information about long-term levels of metabolism and deposits of adipose tissue
• High-density lipoprotein cholesterol and total cholesterol: Indicates protection against atherosclerotic risk
• Glycated hemoglobin: A measure of recent glycemia

According to researchers, these indicators "serve distinct functional purposes in the calculation of allostatic load as a measurement for the burden of stress on the body."

Types of Allostatic Load

McEwen suggests that there are a few different types of allostatic load, including:

• The frequent activation of the allostatic system. This type of allostatic load refers to frequent, repeated exposure to stress.
• Failure to shut off allostatic activity after experiencing stress. This type of allostatic load occurs when a person experiences stress but does not experience a sufficient relaxation response once the event has passed, leaving the body in a lasting state of elevated stress for a long period.
• An inadequate allostatic response leads to other systems remaining elevated after stress. When one stress response is inadequate, other responses may have to overcompensate to help maintain equilibrium.

Several factors are associated with higher allostatic load, including psychosocial factors such as risky health-related behaviors and socioeconomic status. Damaging health behaviors can also increase allostatic load. Such behaviors include lack of exercise, alcohol consumption, poor sleep, smoking, and diet.

Genetics also plays a role since some people tend to have a higher reactivity to stress, which means that environmental stressors may be more likely to contribute to increased allostatic load than they would in people with lower stress reactivity.

Impact of Allostatic Load

Allostatic load can have an impact on the course of health conditions. 

• Cardiovascular disease: Allostatic load is associated with an increased risk of cardiovascular disease, including high blood pressure and hardening of the arteries.
• Diabetes: Allostatic load has also been linked to an increased risk of diabetes. Research has found that people with diabetes tend to have a higher allostatic load. People with the condition were also more likely to display higher exposure to life stresses and more disruption in stress-related processes.
• Cancer: One study found that women with breast cancer were more likely to have higher allostatic load and increased cortisol levels.
• Mental health effects: Repeated stress also affects areas of the brain, such as the hippocampus, which plays an important role in memory and how the body responds to stress. Higher allostatic load is also associated with an increased risk for anxiety and mood disorders, including depression.
• Post-traumatic stress disorder: Early childhood experiences, such as neglect, abuse, and trauma, play a part in creating a higher allostatic load as people age. Research has found that trauma in childhood was linked to increased allostatic load in adulthood and an increased risk for the development of PTSD.

"Changes in allostatic load might reflect adaptive adjustments that maximize short-term survival by enhancing stress reactivity, but at a cost to later health," the researchers concluded in the American Journal of Human Biology study.

Increased allostatic load accounts for health disparities in minoritized communities as well.

Tips for Managing Allostatic Load

Several factors can improve your ability to manage stress, which may help reduce allostatic load. And as always, consider seeking professional mental health services if you are feeling particularly burdened or overwhelmed. 

Change How You Interpret Situations

If you perceive an event as a threat, your body is more likely to mount a stress response, forcing your body to adapt and thus increasing your allostatic load. While you can't always control this, there are times when you can reframe how you think about events to make them less stressful. For example, if you tend to get stressed out by speaking in public, habituating yourself to the experience can make it less stressful.

Engage in Regular Physical Activity

Exercise has a wide range of health benefits, including boosting your ability to cope with stress. While exercising regularly won't eliminate stress, it may make it easier for you to manage stress.

Utilize Effective Relaxation Techniques

Allostatic load is greater when the body does not adequately recover after a stressful event. Incorporating relaxation strategies such as deep breathing, yoga, meditation, and progressive muscle relaxation can help you manage stress as it is happening. It can also help you induce a relaxation response once the immediate threat has passed.

Build Supportive, Healthy Relationships

Social support can act as a buffer against some of the negative effects of stress. One study found that higher levels of spousal support were connected to lower allostatic load.

A Word From Verywell

Ultimately, the way the body works to defend itself leads to both protection and damage. The events that you face each day create challenges. While you might not necessarily perceive these events as stressful, they still create stress on the mind and body that can affect your health and well-being. Taking steps to protect yourself from stress and improve your ability to manage stressful events may keep allostatic load in check.