Health Psychology - Session 11Psychological aspects of pain

Dr. Caroline Meyer

Outline of session

- definitions of pain- including psychological conceptualisation

of pain

- measurement issues

- theories of pain perception

- psychological pain management

Objectives

- evaluate relationship between sensation(e.g., tissue damage) and experience

- outline psychological theories of pain perception

- evaluate attempts to measure pain

- describe social & psychological factors involved in pain perception

Definitions

Although pain is a universal experience, due to itssubjectivity, definitions vary.

Example definition: an unpleasant sensory and emotional experience associated with actual or potential tissue damage

“ there is no direct relationship between physicalpathology and the intensity of pain” IASP, (1993)

Nature of pain - Psychological components

1. Sensory - location, magnitude, sensation(e.g., burning, aching, stabbing)

2. Emotional response - strong negative emotional states (e.g., fear, nausea, anxiety, depression, exhaustion)

3. Evaluative - cognitive responses (unbearable, miserable, annoying, frustrating)

Individuals cognitive response can have an effect onpain perception (e.g., Morley, 1997 - catastrophizing)

Duration of pain

Acute - e.g., injections, post-surgical

Chronic - e.g., back pain, cancer

Different meanings - acute is often ‘expected’ to be short lived and is therefore more bearable than chronic.

Measurement of pain

Why is it important?

- gives health professionals information(e.g., degree of discomfort, severity of problem?diagnosis)

Two types of measures:ObjectiveSelf-report

- associated with patient satisfaction (e.g., Bruster, 1994)

- increases medical knowledge - leads to investigation

Objective measures

- include physiological measures (heart-rate, skin conductance, muscle tension - electromyography (EMG) readings)

Problems with ‘objective’ measures:

- imply relationship between sensation and experience of pain

- weak correlation between physiological measures and reported intensity of pain

- other factors may effect physiological readings (mood, stress, diet, exercise)

- less useful for chronic pain

Self-report measures of painThere is currently no truly objective way of measuringpain. It is also insufficient to use NVC - Fritz (1988)

Patients self-report is the most reliable indicator(e.g., Beyer et al, 1990).

One method of assessment is the Visual Analogue Scale (VAS)

No pain Worst possible pain

10cm

Correlates well with verbal reports of pain intensityissue about perceptual set / relativity

As well as pain intensity, it is useful to be able tomeasure other components (sensation, emotion)

McGill Pain Questionnaire (MPQ - Melzack, 1975)

- VAS - present pain

- adjectives describing sensory experience (e.g., Throbbing, Sharp)

- items describing emotional impact(e.g., tiring-exhausting, fearful)

All rated on a 4-point scale - none (1), mild (2), moderate (3), severe (4)

McGill Pain Questionnaire, continued..

- has been found to be a valid measure of pain(gives a true reflection of the type, extent andimpact of the individual’s current state)

- However, it requires wide vocabulary & ability tomake very specific distinctions between different sensations and different levels

Other alternatives have now been developed to overcome these issues (e.g., Wong/Baker faces rating scale for children,1986)

Measures of pain behaviour

- e.g., facial expressions, verbal complaints, postural changes, medication consumption

- usually measured by observation (instructured setting - e.g., physiotherapy)

- poor correlation with self-report measures, subject to observer bias (e.g., Morley, 1997), increased pain behaviour under certain circumstances (e.g., when spouse present)

- pain behaviours may represent attempts to avoidpain rather than reaction to pain

- people can report pain in the absence of physiological problem (Somatoform Pain Disorder, DSMIV - American PsychiatricAssociation)

- people can report feeling no pain when physiologically it is clear that they should(Dissociation - amnesia, depersonalisation;Alzheimers disease - Scherder et al., 1999, 2000)

- people can deny pain (under report) for many reasons (e.g., cultural - stiff upper lip; fear of addiction to pain relief medication)

Other psychological considerations

Theories of pain

Early theories

- automatic response; early biomedical modelsdirect link between biological state and painperception

- believed pain to be linearly related to extent of tissue damage / intensity of stimulus

BUT:there is not always a clear link (e.g., cause of back pain is unknown in upto 80% of cases; Deyo, 1986)

Gate control theory (Melzack & Wall, 1965)

- gate mechanism modulates pain signals(encompasses both sensory / perceptual information and brain function)

- integrates psychology into the stimulus-response theories of pain

Gate control theory, continued

Brain

expectationsexperiencemoodbehaviour

GateActionsystem

PAIN

Physiological stimuli (from injury)

Large fibres

Small fibres

Taken from Ogden (2000)

- activity in large nerve fibres (touch) inhibits sensation of pain

- signals from cortex can alter the sensation of pain

Influences on pain perception - what opens the gate?

Physical factors - injury, activation of small (pain) fibres

Emotional factors - anxiety, tension, worry, depressionall linked to pain ? Cause & effecte.g., depression magnifies -ve effects of pain (e.g., Verma & Gallagher, 2000)

Behavioural factors - attention to pain, boredom,

Influences on pain perception - what closes the gate?

Physical factors - medication,stimulation of large (touch) fibres

Emotional factors - happiness, optimism, relaxation

Behavioural Factors - concentration, distractione.g., Shiloh et al (1998, Cognitive Therapy & Research) high levels of distraction associated with lower pain reports during childbirth

Pain competes for processing space (Morley,1997)

What other factors might alter the way in which pain is perceived?

1. Genderno evidence of gender differences in pain perception or types of coping (e.g., Holden et al., 1998)

2. Age- previously believed that infants were less

sensitive to pain

- no less sensitive than adults & early experience can have long term effects(physically & psychologically)

- no evidence that elderly patients cope better withpain, although decreased experience in some cases (related to dementia)

3. Personality- ? Is there individual variation in ability to:

detect sensations, pain thresholds, tolerance

- evidence is equivocal - recent study suggests link between extroversion and self-reported pain in women receiving gynaecological treatment (Joseph, 1999)

4. Anxiety and depression

- can be cause or consequence of pain

- treating anxiety and depression (as well as pain)may help in some cases - ? depends upon typeof pain;

chronic pain ineffectivetreatment

anxiety anxiety

acute pain treatmentanxiety anxiety

-e.g., Fordyce & Steger (1979)

5. Self-efficacy

- low self-efficacy associated with increased avoidance (e.g., not engaging in activity due tofeeling as though it will not be effective)

- high levels of self-efficacy associated with low levels of reported pain (e.g., in childbirth; Shiloh et al., 1998)

6. Memory

- some evidence that memories of pain areunreliable (e.g., recall of labour pain - underestimated)

Psychological management of pain

Two main aims:

- help patients to cope more effectively- reduce reliance on drugs

Relaxation

- different techniques (e.g., progressive musclerelaxation) relaxation is incompatible with stress

- helpful because stress and anxiety are important in onset of pain;

- stress has been found to be a significant predictor of intensity of pain (e.g., in Sickle Cell disease;Porter et al., 1998, 2000)

- also, differential responses to stress in those with and without pain

Hassinger et al. (1999). Frequent migraines associated with different physiological response to stress (cardiac output, stroke volume)

Stress can also reduce reliance on several coping techniques (e.g., distraction - rumination)

Hypnosis

- only 15-30% can be hypnotised- little evidence of efficacy ? placebo

Behavioural - e.g., Fordyce (1984)

- aims to reduce disability- focuses on pain behaviours (e.g., excessive

resting)

- works on the assumption that pain behaviours are reinforced (operant conditioning) e.g., care, sympathy (+ve reinforcement) and avoidance of unpleasant events (-ve reinf.)

- Treatment consists of:- identifying stimuli, behaviours & reinforcers- reduction of reinforcement for pain behavs.- increasing ‘well’ behaviours by social

reinforcement

Cognitive Behavioural Treatments e.g., Turk & Fernandez (1991)

- help patient to re-interpret their pain & associated problems - tailored to individual:

Includes;i) initial pain assessmentii) cognitive therapy or re-structuring -

- focuses on appraisals, expectations & beliefs about origin & consequences of pain

e.g., catastrophising beliefs may be challenged with alternatives to provide increased sense of control over pain

- improving mood (reconceptualize problemsuntil viewed as managable)

- redefinition of pain (seen as less negative)

iii) Education / Information provision

- information about different models of pain- helps to engage patient in treatment- requires reflection on individual’s own

understanding of pain

iv) Exercise / activity / sleep management programmes (?changes beliefs / dysfunctional assumptions about disabilities)

Summary & tips

- pain is a subjective experience comprisingphysical, sensory, emotional and cognitive responses

- pain can be affected by: someone’s emotional state, expectations & beliefs

- the most effective way of measuring pain involves self-report, but communication is important here(believe them even if there is little physiological evidence)

- psychological treatments involve a range of techniques - cognitive restructuring, education,anxiety / depression management