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 under-

activity 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