HLSC111

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Stress and Health
 Continuing with psychosocial aspects affecting health and

particularly the role of stress and its possible mechanisms

Week 6 Lecture A PNI, Pain and Health

 We will examine PNI ‐ Psychoneuroimmunology  The immune system – its role in preventing disease  Lect B – coping – what works

Where are we?
 This lect draws a number of threads together:
 So far we have looked at:
 People and ways to understand them  What people share with each other – developmental psychology  What makes people unique – individual differences  The role of groups people belong to  Stress – causes and effects

Psychoneuroimmunology (PNI) What is it?
 PNI ‐ examines the relationships between the mind/brain

and immune system

 “The field that studies the interactions between the central

nervous system, the endocrine system and the immune system; the impact of behaviour/stress on these interactions; and the implications for health of these interactions”  Ronald Glaser

 Now we will examine in more detail the relationship between behaviour,

 1919 ‐ researchers noted increased stress increased the

the nervous system, the endocrine system, immunity and coping ‐ ways to stay healthy
 Back to Physiology

progression of pulmonary tuberculosis.

Research foundations
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Psychosocial factors modulating immunity
Immune system problems result from  Increased Age  Genetic disorders  Infectious diseases  Nutrition  Chemotherapy  Irradiation  Allergies  Stress ‐ and this is the focus of PNI

Many factors affect health and well‐being (Solomon & Moos, 1964)

Emotions affect the development of physical disease (Langley, Fonseca, & Iphofen, 2006)  Different stressors produce different reactions in the body (Ader, 2001)
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These reactions alter the state of homeostasis (Langley et al, 2006).

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Bi‐directional interaction between neuroendocrine and immune systems (Zeller et al, Bi di ti li t ti b t d i di t (Z ll t l 1996)

Reducing stress can boost immunity (Fawzy et al, 1993, as cited in Langley et al, 2006) Responses to stressful experiences involve a complex relationship ‐ behaviour, nervous system, endocrine system and immune system (Rabin, 1999, as cited in Ader, 2001).  Peoples' perception of stress changes and depends on circumstances and the resources they have (Sternberg, 2000).

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Psychosocial factors modulating immunity
 Starting kindergarten can raise cortisol levels and

Cortisol
 Hormone release is triggered by the sympathetic nervous

negatively alter immune measures (Boyce et al.,1995)
 Clinical depression is associated with several alterations in p

system activity:
 Results in increased blood sugar for maximised muscle

immunity
 Reduced lymphocytes  Reduced NK cell activity and  Reduced WBC numbers (Herbert & Cohen, 1993)

endurance
 Decreases proteins synthesis including those essential to

the immune system
 Suppresses T cell numbers

An overview of the immune system

Cytokines
 Cytokines ‐ chemicals secreted by the immune system affecting the NS  influence sensory neurons and induce symptoms of illness
 fever  increased sensitivity to pain  loss of energy  loss of interest in usual ADLs  poor appetite  sleep changes

 Cytokines coordinate immune system activities  Can cross blood brain barrier and modify hormone levels, including

cortisol

The Immune System ‐ cont
 Leukocytes: Subtypes and Functions  Produced by bone marrow ‐ travel to spleen, thymus, and lymph nodes  M Macrophages – Fi li f d f h First line of defense, destroy antigens, signal d i i l lymphocytes  Lymphocytes – B cells (humoural branch ) and T cells (cellular branch)  B cells produce antibodies, but T cells do not  Functional role of B cells, T cells, and memory cells
 

Immune system functions
Intact skin and mucous membranes block most foreign substances Immune system protects the body when foreign organisms enter by detecting antigens (antibody generator molecules):  bacteria  viruses  parasites

 fungi Immune system attack cancerous and diseased cells  Immune system identifies and eliminates (non‐self) material  Antigens are proteins on the surface of microorganism that differ from those of host 

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Immune system functions
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Nonspecific Responses
Phagocytosis‐ the attack of foreign particles by leukocytes  Granulocytes release chemicals  Macrophages  Inflammation‐  Basically increased blood flow aids in restoration of cells and destruction of y invaders  Has been linked to “heart attacks” and “strokes” – initiates the release of blood clots blocking, arteries  Immunity  A specific, rapid response to foreign microorganisms based on previous exposure  Vaccination ‐ Induced immunity
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 Intact skin and mucous membranes block most foreign substances.  Two types of responses to invaders  Non‐specific responses
 Phagocytosis  inflamamation  Specific Immune system responses  T‐cells  B‐cells

Surface protein introduced into the body to stimulate the production of antibodies – live attenuated or dead virus/bacteria

Mood and the Immune System
 Psychosocial variables alter susceptibility, progress, recurrence of     

Risk and Protection
 Effects on Immune Function – Risk factors  factors including, anxiety, sleep deprivation, abortion, divorce, family illness, unemployment, personality, coping style, psychiatric illness, and war impact immune function
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immune system diseases and coping (Taylor, 1999) Negative emotions induced by stress affect the immune system Emotions such as sadness, grief, and helplessness, suppress immune function Individuals are 3 times more likely to die as a result of their illness if they are depressed, compared to a control group Cancer patients who are depressed have lower natural killer cell activity (NKCA) Depression, anxiety and associated traits of cynicism, hostility and anger are highly associated with cardiovascular disease and with pain problems

Reilly & McCabe, 1997

 Protective Factors  the immune system and disease are improved by relaxation, humour, hypnosis, meditation, and positive attitudes  These techniques induce a physiological “relaxation response” (as opposed to the stress “fight‐or‐flight” response), reducing BP, respiratory rate, pulse

Pain
 Acute Pain  Occurs with tissue damage or potential damage
 Is a symptom

Pain Classification ‐ 1
 Nociceptive pain – involves stimulation of the peripheral neurons

above their threshold level eg thermal (burning), mechanical (cutting, crushing), chemical
 Maybe viseral, deep, superficial,

 Protects from tissue damage and or until healing has occurred Protects from tissue damage and or until healing has occurred

 Inflammatory pain
 Associated with tissue damage  Infiltration of immune cells

 Persistent Pain (Chronic Pain)  Extends beyond normal tissue healing time, and/or  Causes challenges greater than expected from tissue injury or medical findings, and/or  Occurs without known tissue damage

 Pathological pain
 Disease state caused by damage to the nervous system or abnormal

function eg fibromyalgia, tension headaches, irritable bowel syndrome

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Pain Classification ‐ 2
 Acute vs. Chronic Pain  Acute – Disappears within 1 month  Chronic – Does not decrease over time >3 months  Severity of pain does not predict one’s reaction to it Severity of pain does not predict one s reaction to it  Psychological and Social Factors in Chronic Pain  Perceived control over pain and its consequences  Negative emotion, poor coping skills  Low social support, compensation  Social reinforcement for pain behaviors  Gate Control Theory  Endogenous Opioids  Gender Differences

Pain classification
ACUTE PAIN
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CHRONIC PAIN
Persistent / longstanding ~ beyond 6-12 months 2. Pain does not an indicate ongoing tissue damage 3. Hurt usually does not = harm 4. No longer a useful warning sign 5. Biopsychosocial factors are very relevant 6. Pain remains after healing Challenge: to manage chronic pain

1. Short term pain - < 3 months duration 1. Pain persists beyond reasonably expectation for healing

2. Indicates tissue damage 3. Pain = harm 4. Warning /protective sign/process 5. Biopsychosocial factors are important 6. As healing takes place the pain settles and normal function returns (pain may recur)

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Models of Pain
 Historical  Specificity Theory
 Separate nerve endings for each type of sensation (temperature, touch,  

Models (continued)
 Gate Control Theory (Melzack and Wall, 1965)
Physiological and psychological components of pain Nerve ending signals are modulated in the spinal cord
 Large (non‐nociceptor) and small (nociceptor) diameter afferent signals to the substantia    

pain)
 Challenged: Phantom limb pain? Blockage of pain pathways?

 Pattern Theory
 Pain recognized by “sense organs” in skin  Consists of signals in the CNS  Sensation is a learned event – no specific pathways for each sensation 

gelatinosa (SG) and T cell T cell initiates consequences of pain T cell initiates consequences of pain SG substantia gelatinosa cells are inhibitory to the T cell Nociceptor signals inhibit the SG neurons, therefore allowing pain signals to continue Increased signals from large diameter fibers results in increased firing of substantia gelatinosa neurons, which ultimately decreases firing of T‐cells

Prostaglandins are released during inflammation and increases pain response

Pain
 Pain is a perception – the end of a complex process  Pain is (including the acute stage) a combination of
 biological  psychological and  social factors – the biopsychosocial framework

Pain
Psychosocial factors are MORE important than physical, biomedical or treatment in:
  

Pain perception

 “pain is a CNS phenomenon, that treatments for pain must be aimed

The continued report of symptoms Health care seeking  Response to treatment  Overall outcome
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not only at the peripheral nervous system but also at modulating the CNS, and that pain is multidimensional.” 2

The prediction of disability The development of disability  The maintenance of disability  Prolonged workloss
(Gatchel, 1995; Klenerman, 1995; Symonds, 1995; Burton, 1995; Deyo 1988; Koes, 2001; Power, 2001; Pincus, 2002)

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The Placebo Effect
 The placebo effect is defined as: “a change in a

Exploring Physical Disorders

patient’s illness attributable to the symbolic importance of a treatment rather than a specific pharmacologic or physiologic property pharmacologic or physiologic property”.
 autonomic nervous system: (with improvements in hypertension,

 Benefits of placebos involve cardiac pain, and headaches)
 the endocrine system: (diabetes and menstrual pain)  the immune system: (colds, asthma, and cancer)

Exploring Physical Disorders (cont.)

Exploring Physical Disorders (cont.)

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