The Relationship Between Stress & Illness

Relationship Between Stress and Illness

Overview

  • Stress and illness have a significant interrelationship.

  • Key studies identify the role of the mind and brain in immune response.

Key Experiments

  • Study by Robert Ader and Nicholas Cohen:

    • Rats given sweetened water (neutral stimulus) before receiving a nausea-inducing drug (unconditioned stimulus).

    • Resulted in conditioned aversion to the sweetened water.

    • Observations showed illness and death in rats due to immune suppression from the drug, which mirrored responses to the sweetened water.

    • Concluded that mind-body connection is crucial for understanding the immune system.

  • Candace Pert's Discovery:

    • Identified that the brain has receptors for immune molecules, showcasing its influence over immune system activities.

Psychoneuroimmunology

  • Coined by George Solomon, emphasizing interactions between psychological processes, the neuroendocrine system, and immunology.

  • Focuses on how behaviors influence health through immune mechanisms.

  • Demonstrated that experiences such as divorce or bereavement can lead to immunosuppression.

Stress Impact on Immune Function

  • Stress correlates with decreased resistance to infections (e.g., colds) and slower wound healing.

  • Two key hypotheses regarding stress and disease:

    1. Direct Effect Hypothesis:

      • Immunosuppression results from stress affecting immune efficiency via the HPA (Hypothalamic-Pituitary-Adrenal) and SAM (Sympathetic-Adrenal-Medullary) axes.

      • T and B cells have receptors that respond to stress hormones (Corticosteroids and catecholamines).

      • Activation leads to reduced immune response and can increase risks such as hypercoagulable states, leading to heart disease and stroke.

    2. Indirect Effect Hypothesis:

      • Stress leads to maladaptive behaviors (e.g., smoking, poor diet) that negatively impact health.

      • Poor sleep quality affects immune responses negatively.

Allostatic Load

  • The accumulation of long-term physiological stress responses is termed Allostatic Load.

  • Stressors that are unpredictable or prolonged can lead to adverse health effects, including:

    • Decreased immunity

    • Increased abdominal fat

    • Changes in hormone levels (e.g., elevated epinephrine)

    • Overproduction of cytokines

  • Unchecked allostatic load increases illness and mortality risk.

Glucocorticoid Receptor Resistance Model

  • Chronic stress generates resistance to cortisol, the hormone responsible for regulating inflammatory responses.

  • Results in heightened inflammation, exacerbating chronic diseases (e.g., cardiovascular disease).

General Adaptation Syndrome (GAS)

  • Proposed by Hans Selye, GAS outlines three stages:

    1. Alarm Phase: Fight or flight response.

    2. Resistance Phase: High physiological arousal as the body copes by replenishing adrenal hormones.

    3. Exhaustion Phase: Depleted energy leads to potential hypocorticollism (lack of cortisol), resulting in disease or death.

  • Critiqued for underestimating psychological factors impacting stress.

Transactional Model of Stress

  • Focuses on the dynamic interplay between environmental stressors and individual responses.

  • Involves two appraisals:

    1. Primary Appraisal: Evaluating if the event is a threat.

    2. Secondary Appraisal: Assessing resources to cope with the stressor.

  • Cognitive reappraisal affects how stress is perceived and managed.

Diathesis-Stress Model

  • Explains individual susceptibility to illness based on:

    • Predisposing factors (genetic vulnerability, behavioral traits)

    • Precipitating environmental factors (traumatic experiences)

  • Illustrates why certain individuals develop PTSD after trauma, while others do not.

Post-Traumatic Stress Disorder (PTSD)

  • Triggered by extreme traumatic experiences (combat, environmental disasters, etc.).

  • Symptoms include:

    • Haunting memories, nightmares

    • Sleep disturbances

    • Excessive guilt and distress

  • Associated with increased inflammation and stress hormone levels.