Psychoneuroimmunology and Stress

Introduction to Psychoneuroimmunology (PNI)

Psychoneuroimmunology (PNI) is the interdisciplinary study of how psychological processes, the nervous system, and the immune system interact to influence health and disease. This field highlights the complex connections between mind and body, emphasizing that psychological factors can directly affect physical health.

• Disease was once viewed as purely biological, but psychological factors such as stress, emotions, and beliefs are now recognized as influential.

• Stress can suppress immune functioning, while positive emotions and social connections can boost immune responses.

• Sleep and immunity are closely linked; sleep deprivation weakens immune defenses.

Key Mechanisms of Stress and Immunity

• HPA Axis Activation: Stress activates the Hypothalamus-Pituitary-Adrenal (HPA) axis, leading to the release of cortisol and adrenaline.

• Chronic exposure to these hormones suppresses immune cell activity, increasing vulnerability to illness.

Stress During COVID-19: An Applied Example

• Major Stressors: Financial insecurity, social isolation, increased mental health disorders (anxiety, depression, PTSD).

• Health Impact: Chronic stress weakened immune resistance, increased sleep disruption, emotional exhaustion, and heightened health anxiety.

Understanding Stress

Defining Stress

Stress is a person’s psychological and physiological response to events perceived as threatening, challenging, or exceeding their resources. Stress is subjective and depends on individual perception, not just the event itself.

• Stressful situations are those perceived as important or threatening, especially when resources to cope are lacking.

Lazarus & Folkman’s Transactional Stress Model

This model views stress as a dynamic interaction between the person and their environment, emphasizing cognitive appraisal.

• Primary Appraisal: Assessing if an event is relevant, harmful, threatening, or challenging.

• Secondary Appraisal: Evaluating available resources and coping abilities.

• Outcome: High resources can make stress motivating; low resources can make it overwhelming.

Categorizing Stressors

• Cataclysmic Stressors: Sudden, large-scale events (e.g., natural disasters, war, pandemics).

• Personal Stressors: Major life changes (e.g., death of a loved one, divorce, job loss, marriage, serious illness).

• Background Stressors (Daily Hassles): Chronic, low-level irritants (e.g., traffic, deadlines, social conflict).

Key Insight: Background stressors often have the most damaging long-term health effects due to their continuous and cumulative nature.

Post-Traumatic Stress Disorder (PTSD)

PTSD is a psychological disorder that develops after exposure to traumatic events involving threat, helplessness, or fear.

• Core Symptoms: Re-experiencing (flashbacks, nightmares), emotional numbing, hyperarousal, avoidance, increased substance use or suicidal ideation.

• Neutral stimuli can trigger traumatic memories; loss of perceived control increases PTSD risk.

Personal Stressors: Psychological Categories

• Life Changes: Measured using the Holmes-Rahe Social Readjustment Scale.

• Conflict: Incompatible motivations (approach-approach, avoidance-avoidance, approach-avoidance).

• Frustration: Blocked or thwarted goals.

• Pressure: Mismatch between demands and resources.

Holmes-Rahe Life Stress Inventory

• Measures cumulative stress from major life events over 12 months.

• Higher scores predict increased risk of physical illness and mental health disorders.

Stress & Technology

• More screen time is associated with higher rates of anxiety and depression (Twenge et al., 2018).

• Mechanisms include reduced physical activity, sleep disruption, increased social comparison, and constant cognitive stimulation.

The Biology of Stress

Stress Hormones

• Adrenaline (Epinephrine): Immediate fight-or-flight response.

• Cortisol: Long-term energy regulation and immune suppression.

Short-Term vs. Chronic Stress

• Short-Term (Adaptive): Increased heart rate, blood pressure, breathing, and alertness.

• Chronic (Maladaptive): Cardiovascular damage, weakened immune system, increased inflammation, greater illness vulnerability.

Stress & the Immune System

• The immune system defends against disease and abnormal cell growth.

• Chronic stress reduces immune efficiency by suppressing lymphocyte (white blood cell) activity.

Psychophysiological Disorders

Physical conditions caused or worsened by psychological stress, such as headaches, hypertension, digestive disorders, skin conditions, and chronic fatigue.

General Adaptation Syndrome (Selye)

• Alarm: Initial shock and activation of stress response.

• Resistance: Body attempts to adapt and cope.

• Exhaustion: Resources depleted, illness risk rises.

Criticism: GAS ignores individual differences in perception and appraisal, assuming a uniform biological response.

Stress & Health Behaviors

• Stress impacts health by causing direct physiological damage, promoting unhealthy behaviors (smoking, overeating), and producing indirect social and emotional consequences.

Personality and Health

Personality & Coronary Heart Disease

• Type A: Competitive, time-urgent, hostile, high achievement orientation.

• Type B: Relaxed, patient, cooperative.

• Type D (Distressed): Anxious, socially inhibited, negative emotional outlook.

• Key Finding: Hostility is the strongest predictor of heart disease, increasing stress hormones, blood pressure, and heart rate.

Psychological Factors in Cancer

• Emotional coping affects quality of life but not survival rates.

• Therapy can improve emotional well-being and immune functioning.

• Stress suppresses immune surveillance of abnormal cells.

Positive Psychology & Health

Uplifts

• Small positive experiences buffer stress, improve mood, and build resilience.

Exercise & Brain Health

• Increases dopamine, epinephrine, and BDNF (brain-derived neurotrophic factor).

• Improves memory, cognitive processing, and reduces dementia risk.

Meditation

• Reduces cortisol, improves attention and sleep, lowers inflammation.

Coping Strategies

Emotion-Focused Coping

• Regulates emotional response (e.g., talking to friends, relaxation, distraction).

Problem-Focused Coping

• Targets the stressor itself (e.g., planning, seeking help, skill-building).

Resilience & Hardiness

• Resilience: Ability to recover from adversity.

• Hardiness Traits: Commitment, control, challenge.

Sense of Control

• Perceived Control: Belief in ability to influence outcomes; linked to better mental health and coping.

• Locus of Control: Internal (“My actions matter”) vs. External (“Life happens to me”).

Learned Helplessness

• Repeated exposure to uncontrollable stress leads to passivity, loss of motivation, increased depression and anxiety.

Compensatory Control

• When personal control is low, people seek external systems (religion, government, social systems, conspiracy beliefs) to restore a sense of order.

Expressive Writing & Health (Pennebaker Studies)

• Writing about trauma improves immune function and reduces health visits, especially when emotions are disclosed rather than suppressed.

Maladaptive Coping

• Avoidance, substance use, excessive screen time, social withdrawal, doomscrolling.

The Power of Prayer & Meaning-Based Coping

• Associated with lower complications and better emotional health; may improve immune functioning through stress reduction and social connection.

Personality Theories

Trait Theories

• Personality traits are enduring psychological characteristics that predict behavior.

• Gordon Allport: Identified cardinal, central, and secondary traits.

The Big Five (Five Factor Model)

• Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism.

• Traits are universal but vary in emphasis across cultures.

• Predict real-world outcomes (e.g., conscientiousness predicts academic/job success).

• Traits change over time (maturity principle).

HEXACO Model

• Adds Honesty-Humility to the Big Five.

• High HH: Sincere, honest, modest; Low HH: Deceitful, greedy, manipulative.

Stability of Personality Traits

• Traits are relatively stable over time; infant temperament predicts adult personality.

Behaviorist and Social Cognitive Perspectives

• Personality is shaped by learned behavior patterns (Skinner).

• Social cognitive approaches emphasize observational learning and reciprocal determinism (Bandura).

• Self-efficacy: Belief in one’s ability to succeed in specific situations.

Cultural Influences on Personality

• Individualist cultures: Value independence and personal achievement.

• Collectivist cultures: Value social harmony and group needs.

Biological Approach

• Genetic factors contribute to personality; twin studies show strong similarities even when raised apart.

Psychoanalytic Theory (Freud)

• Unconscious forces shape personality (id, ego, superego).

• Personality develops through psychosexual stages (oral, anal, phallic, latency, genital).

• Defense mechanisms protect the ego from anxiety (e.g., repression, denial, projection).

Neo-Freudians

• Carl Jung: Collective unconscious and archetypes.

• Karen Horney: Challenged Freudian gender assumptions; emphasized social factors.

Birth Order and Personality

• Firstborns score slightly higher on intelligence; no lasting effects on personality traits.

• More siblings may promote higher honesty-humility and agreeableness.

Humanistic Approaches

• Emphasize unique and positive qualities, free will, and self-actualization (Maslow, Rogers).

• Self-concept and unconditional positive regard are central to healthy personality development.

Personality Assessment

• Self-report measures (e.g., MMPI-2) and projective tests (e.g., Rorschach, TAT) are used to assess personality traits and disorders.

The Dark Triad (and Tetrad)

• Psychopathy: Impulsivity, thrill-seeking, low empathy.

• Narcissism: Grandiosity, entitlement, need for admiration.

• Machiavellianism: Manipulativeness, cynicism, lack of emotional attachment.

• Sadism (Dark Tetrad): Pleasure from inflicting pain or suffering.

These traits are associated with negative interpersonal outcomes and maladaptive behaviors.