Health Psychology
Lecture 5
Pain
Lecture 5 - Outline
• Part 1
– Anna Nagy (Stress)
• Part 2
– Duane (Pain)
• Part 3
– Term Test #1 Preparation
Question
What is pain?
Pain is the sensory and emotional experience of
discomfort which is usually associated with actual
or threatened tissue damage or irritation
(Sarafino)
Types of Pain
Acute vs. Chronic Pain
ie - short-term vs. long-term pain
Psychological impact of chronic pain depends on…
• Chronic benign pain
• Recurrent acute pain
• Chronic progressive pain
Physiology of Pain Perception
Overview
Specialized nerve fibers transmit perception of pain to
the brain
• Noxious stimuli  algogenic chemicals
• Algogenic chemicals  activate nociceptors
• Nociceptors  nerve impulses to brain
Physiology of Pain Perception
Pain signals travel along 2 types of nerve fibers
• A-delta: sharp, well-localized pain
• C fibers: diffuse, dull, aching or burning pain
Non-pain signals travel along A-beta fibers
• Touch, pressure, warmth, mild irritation
(Experience of non-pain sensations relevant to perception of pain)
Gate-Control Theory
Extent to which gate is open depends on…
• Amount of activity in pain fibers
• Amount of activity in non-pain fibers
• Messages descending from the brain
Endogenous Opioids
Endorphins and Enkephalins
• Exist in the brain, spinal chord and other organs
• Released in response to stress or trauma
• Messages descending from the brain
Pain Behaviors
Behaviors specifically associated with pain - usually
indicate the presence of pain to the onlooker
•
•
•
•
Facial/audible expressions
Statements
Altered gait or posture
Avoidance of tasks
Assessing or Measuring Pain
1. Psychophysiological measures
• Muscle tension (Electromyograph, EMG)
• Indices of autonomic activity
– Heart rate (ECG), skin conductance
• Evoked potentials (EEG)
Assessing or Measuring Pain
2. Measurement of Pain Behaviors
• Behavior checklist
3. Self-report measures
• Interview
• Rating Scales
• Pain Questionnaires (McGill Pain Questionnaire)
McGill Pain Questionnaire
Measures 3 dimensions of pain experience
• Sensory - location, temporal pattern, quality
• Affective - emotional response (e.g., annoying)
• Evaluative - perceived intensity
Pain Management
Physical/Medical Treatment
• Chemical Analgesia (pain relief)
– Narcotics (e.g., morphine)
– Peripherally acting analgesics (e.g., asprin)
Pain Management
Physical/Medical Treatment
• Surgical approaches
– Severing peripheral nerves
– Spinal tracts
Pain Management
Physical/Medical Treatment
• Acupuncture
– insertion of metal needles under the skin at
acupuncture points
– Endorphins and enkephalins
Pain Management
Physical/Medical Treatment
• Transcutaneous Electrical Nerve Stimulation
– Electrodes on area of pain
– Stimulates non-pain fibers (A-beta)
Pain Management
Psychological Intervention
• Hypnosis
– Altered state of consciousness
– Produces a high degree of analgesia in a
minority of individuals
Pain Management
Psychological Intervention
• Biofeedback
– Feedback using EMG (muscle tension)
– Teaches awareness and control of bodily
processes
Pain Management
Psychological Intervention
• Relaxation Techniques
– Meditation, progressive muscle relaxation
– Relaxation reduces anxiety
Pain Management
Psychological Intervention
• Cognitive Therapy
– Assumption: Cognitive variables impact the…
• Interpretation of pain
• Affective features that accompany pain (depression)
– Aim: Challenge and replace pain beliefs
• Pain beliefs “promote disability and engender distress”
Pain Management
Psychological Intervention
• Behavior Therapy
– Assumption: Pain behaviors increase attention to pain,
interfere with activities, reduce fitness
– Aim: Eliminate reinforcement of pain behaviors
– Aim: Provide reinforcement for healthy behaviors
Pain Management
Evaluating Psychological Interventions
• CBT (cognitive-behavior therapy)
– Enhance mood and mobility
– Reduce pain perception and pain behavior
– But … CBT is not a panacea (pain eliminator)
Current Topics
• Effects on Cognition/Learning and Memory
– Animal research—How stress affects the brain
• Hippocampus—high concentration of GC receptors
• Stress=Increased cortisol secretion in most cases
• Atrophy of dendrites/Effects on neurogenesis
– Sex differences
– Suggestive Evidence in humans
• Hippocampal volume loss? (Cushings, Depression, PTSD)
• prevent access to contextual info (may lead to enhanced fear based
memory (PTSD))
• Caregiver study
• Allostatic Load
Stress Affects Health
• Acute Stress Enhances Immunity—
– Enhances traffic of lymphocytes and macrophages to the area of
need (‘delayed-type hypersensitivity’)
– Dependent on adrenal secretion; last 2-5 days
– Enhances responses for which there is an immunologic memory
(beneficial for cancer or tumour cell, but pathologic for
autoimmune or allergic responses)
• Can you think of any diseases where this might be a factor?
Allostasis
• Allostasis: ability to achieve stability through
change—crucial to survival
• Accommodation: Body protected by various
systems including ANS, HPA, cardiovascular,
metabolic and immune systems
• Allostatic Load: long term effects of the
physiologic response to stress.
– Wear and tear from chronic over-activity or underactivity of systems
The Stress Response and the
Development of Allostatic Load
Stress Response and Development of Allostatic Load.
(McEwen, 1998)
Four Situations Associated With
Allostatic Load
• Frequent Stress
• No Adaptation to Repeated Stressors in Some
Individuals
• Failure to shut off stress response after stressor
abates
• Inadequate responses in some allostatic
systems=compensatory responses in other systems
(disruption of counter-regulatory mechanisms)
HPA