The connection between stress and disease

The connection between stress and disease

The connection between stress and disease has been proven by many scientific studies.  This article explores some of those studies and indicates some of the correlations not only with stress but also negative thoughts, some of which are surprising.  Let’s focus firstly on stress and disease:


Stress and disease

The General Adaptation Syndrome (GAS)

Hans Selye, a scientist and researcher, was the first to identify a syndrome called the General Adaptation Syndrome (GAS) in 1936, which identifies a physiological three-stage process that your body goes through to adapt to danger.

The three stages of GAS are:

  1. alarm reaction
  2. resistance
  3. exhaustion

The connection between stress and disease

Source: Wikipedia

Alarm Reaction Stage

The Alarm Reaction stage is when the body sends a signal to the hypothalamus in the brain to trigger the release of glucocorticoids which increase in adrenal and cortisol levels as a fight or flight reaction. This increases the heart rate, blood pressure and blood sugar, pulling away resources from the digestive system so that nutrients can be used in the blood.

The Resistance Stage

The next phase in the resistance stage.  Modern-day stressors typically drive us to stay in this stage longer than our body was designed to cope with  This is when the body tries to normalise and adapt to the situation. The body’s defence system moves resources to heal and return to homeostasis. Hormones such as cortisol and adrenaline are reduced but are still kept slightly elevated due to continual stress. Blood pressure and blood sugar remain high and on alert. However, if the stress continues, which is the case with many modern types of stress, the body is weaker and the result can be irritation and lack of concentration. The immune system is depleted over weeks, months and years and the exhaustion stage is entered.

Exhaustion stage

At some point, the body can’t go on and moves into the exhaustion stage. If the body goes into this phase, the stress has been persistent for a long time and the body has failed to cope with the stressor. If the cortisol and adrenalin are depleted, the body goes into exhaustion.  The result can be the following:

  • decreased stress resistance
  • anxiety
  • inability to cope
  • tiredness
  • depression

If stress is not managed the immune system is weakened and the body can become susceptible to chronic disease.

This is not just a theory, there are many studies showing a link between stress and disease, specifically, chronic disease and ageing:

Stress and Chronic Disease

A study conducted by the University of Pittsburgh investigated chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. Glucocorticoids (GC) are hormones with a wide variety of actions, including anti-inflammatory and immunosuppressive effects. The study suggested that “chronic stress results in glucocorticoid receptor resistance (GCR) that, in turn, results in failure to down-regulate inflammatory response” and “prolonged stressors result in GCR, which, in turn, interferes with appropriate regulation of inflammation. Because inflammation plays an important role in the onset and progression of a wide range of diseases, this model may have broad implications for understanding the role of stress in health.”

A book written by Kathleen Kendall-Tackett entitled The psychoneuroimmunology of chronic disease: Exploring the links between inflammation, stress, and illness a group of researchers explore the ways physical and psychological stressors such as posttraumatic stress disorder, depression, and poor sleep trigger the inflammatory response and increase the risk of disease.

Stress and Ageing

A study conducted by the University of California, San Francisco investigated the effect of stress on cellular ageing and cardiovascular disease risk factors. They studied telomere length. Telomeres are DNA–protein structures which are found at both ends of each chromosome. Telomere length shortens with age. Shorter telomeres have been associated with an increased incidence of diseases and poor survival.  They concluded “cellular mechanisms by which low telomerase may link stress and traditional risk factors to cardiovascular disease” and that “telomerase [is an] important mediator of the effects of psychological stress on physical health and disease.”

A study conducted by the University of Minnesota,  investigated chronic stress, depressive symptoms, anger, and hostility in relation to incident stroke and transient ischemic attacks in middle-aged and older adults. The results concluded “Higher levels of stress, hostility, and depressive symptoms are associated with significantly increased risk of incident stroke or transient ischemic attacks in middle-aged and older adults

Recently the Mayo Clinic published an article linking stress to symptoms on your body, mood and behaviour.

Thoughts, emotions and ill health

If we take this one step further, we can see that there is a proven and scientific link between our thoughts (memories, values and beliefs) and emotions and our health which are validated by numerous studies.  Here are some examples

A study conducted by The Ohio State University College of Medicine investigated emotions, morbidity, and mortality. The study concluded a number of points:

  • “Negative emotions can intensify a variety of health threats
  • inflammation has been linked to a spectrum of conditions associated with ageing, including cardiovascular disease, osteoporosis, arthritis, type 2 diabetes, certain cancers, Alzheimer’s disease, frailty and functional decline, and periodontal disease. Production of proinflammatory cytokines that influence these and other conditions can be directly stimulated by negative emotions and stressful experiences
  • negative emotions also contribute to prolonged infection and delayed wound healing, processes that fuel sustained proinflammatory cytokine production.
  • distress-related immune dysregulation may be one core mechanism behind a large and diverse set of health risks associated with negative emotions.
  • Resources such as close personal relationships that diminish negative emotions enhance health in part through their positive impact on immune and endocrine regulation”

A study conducted by University of Eastern Finland, found that “Optimism is associated with a reduced incidence of coronary heart disease and total mortality” and “Conversely, cynical hostility was associated with an increased risk of total mortality and cancer-related mortality.”

In addition, a study conducted by the University of Pittsburgh, looked at the trait of optimism (positive future expectations) and cynical, hostile attitudes toward others in relation to incident coronary heart disease and mortality in postmenopausal women. The study concluded that “Association between cynical distrust and incident dementia became evident

Most of the studies cited so far have concerned adult stress or negative thoughts on health.  What are the implications of childhood stress on our adulthood?

Early Childhood Stress implications on adulthood disease

The University of Thessaloniki investigated the long term effects of early childhood stress on later life health. The study indicated that there was  “cumulative long-term risk of disease vulnerability in adulthood”

A study published by the National Center for Chronic Disease Prevention and Health Promotion found that “Childhood traumatic stress increased the likelihood of hospitalization with a diagnosed autoimmune disease decades into adulthood. These findings are consistent with recent biological studies on the impact of early life stress on subsequent inflammatory responses.”

A study conducted by Cousins Center for Psychoneuroimmunology investigated the effect of early childhood stress on later life health.  it was found that “Adverse social relations in early life are thought to negatively influence health throughout the lifespan” also “Our findings suggest that a loving relationship may also prevent the rise in biomarkers indicative of disease risk across numerous physiological systems, impacting adverse health outcomes decades later”

A review of 23 studies was conducted to find a link between Psychological Stress and Mitochondria: Mitochondria are the organelles that supply power to cells. the conclusion of the study was “Overall, evidence supports the notion that acute and chronic stressors influence various aspects of mitochondrial biology, and that chronic stress exposure can lead to molecular and functional recalibrations among mitochondria”

Prenatal maternal stress and disease

Even beyond childhood, a study conducted by Channing Laboratory indicated that prenatal maternal stress and early caregiving experiences may have implications for childhood asthma risk. The study concluded “it is notable that our laboratory has also linked early‐life caregiver stress to repeated wheeze and dysregulation of immune function”

The best and most well-known example of thought/body connection is the placebo effect.

The placebo effect

What is the placebo effect?  Here is an excerpt from Harvard Medical School

The idea that your brain can convince your body a fake treatment is the real thing — the so-called placebo effect — and thus stimulate healing has been around for millennia. Now science has found that under the right circumstances, a placebo can be just as effective as traditional treatments.

“The placebo effect is more than positive thinking — believing a treatment or procedure will work. It’s about creating a stronger connection between the brain and body and how they work together,” says Professor Ted Kaptchuk of Harvard-affiliated Beth Israel Deaconess Medical Center, whose research focuses on the placebo effect.


watch this video to see how the brain and body interact to impact the immune system and how these interactions affect the likelihood of developing disease.

A study conducted by Cousins Center for Psychoneuroimmunology (featured in the video above) investigated the effect of early childhood stress on later life health.  it was found that “Adverse social relations in early life are thought to negatively influence health throughout the lifespan” also “Our findings suggest that a loving relationship may also prevent the rise in biomarkers indicative of disease risk across numerous physiological systems, impacting adverse health outcomes decades later”

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