Placebos
and the interrelationship among beliefs,
behaviour, and health
Roland Tisljár Ph.D.
Institute of Behavioural Sciences
[email protected]
Reading
Ogden, J. (2007). Health Psychology. A textbook.
McGraw-Hill
– Chapter 13: Placebos
What is placebo
• Inert substances that cause symptom
relief
• Substances that cause changes in a
symptom not directly attributable to
specific or real pharmacological actions
of a drug or operation
• Any therapy that is deliberately used
for its non-specific psychological or
physiological effects
History of inert treatments
Faith healers
‚Medicines’ without any apparent medical (active) properties
Modern day placebos
• Multitude of effects
– Increase performance on a cognitive test (e.g. Ross and
Buckalew, 1983)
– Effective in reducing anxiety (e.g. Downing and Rickels,
1983)
– Have some affect on a whole series of areas
• Allergies, asthma, cancer, diabetes, enuresis, epilepsy,
multiple sclerosis, insomnia, ulcers, obesity, acne,
smoking, and dementia
– One of the most studied areas is pain
• Subjective and objective pain reduction
Placebo theories
• Non-interactive
– Individual characteristics
– Characteristics of the treatment
– Characteristics of the health professional
• Interactive
– The process involved in the interactions between
patients, the treatment and the health
professionals
Non-interactive theories
• Characteristics of the individual
– Emotional dependency, extroversion, neurosis, being highly
suggestible, introverted
– Little evidence to support consistent traits
• Characteristics of the treatment
– If a treatment is perceived as serious – the effect will be greater
• Surgery > injection ,
two pills > one pill,
larger pill > smaller pill
• Problems
– Ignore the interaction
– Assume these factors exist in isolation
• Can be examined independently of each other
Possible mechanisms of interactive
theories
• Experimenter bias
• e.g. Gracely et al. (1985) – interaction between the doctor and the patient
– The experimenter is capable of communicating their expectations to
the subjects
• Who respond in accordance with this expectations
• Patient expectations
– The patients expect to get better
• Any changes that they experience are attributed to the drugs they have taken
• Reporting error
• Misattribution of symptom changes to placebo
– By the patient and/or by the doctor
– Problems
• Not all reported symptoms are positive
• Objective changes in heart rate, blood pressure
Possible mechanisms of interactive
theories
• Conditioning effect
– Patients associate certain factors with recovery and an
improvement in their symptoms
• e.g. presence of doctors, white coat, pills, injections, surgery
• A placebo drug is more effective in a hospital setting when given
by a doctor
• Anxiety reduction
– Placebos decrease anxiety , thus helping the patient to
recover
– GCT of pain – close the gate and reduce pain
– There are many other effects of placebos besides pain
reduction (!)
The central role of patient
expectations
All theories of placebo involve the patient expecting to get better
Cognitive dissonance theory of
placebo (Totman, 1976, 1987)
• Attempted to remove patient expectations
from the placebo equation
– Emphasized justification and dissonance
• All of these treatments required investment
by the individual
– Money, dedication, pain, time, inconvenience
– e.g. If medically inactive drugs were freely
avaliable they would not be effective
Cognitive dissonance theory of
placebo (Totman, 1976, 1987)
• The effect of investment – two processes:
1) The individual needs to justify their behaviour
2) The individual needs to see themselves as rational
and in control
– If these two factos are in line with each other
– „I spent money on treatment and it worked.”
• Low dissonance
– If there is a conflict between these two factors
– „I spent money on treatment and I do not feel any better”
• High dissonance
– High/low justification results in low/high guilt and
dissonance (!)
Cognitive dissonance theory of
placebo (Totman, 1976, 1987)
• For a placebo
effect to occur,
the individual
does not require
an expectation
that they will get
better
– But a need to
find
justification
for their
behaviour and
a state of
cognitive
dissonance to
set this up
Support for cognitive dissonance
theory
• It can explain all placebo effect, not just pain
• It does not require patient expectations, but choice.
– This helps to explain those instances where the individual
does not appear to expect to get better
• It suggests that the individual needs commitment to
the medical procedure
– Which explains why the individual may need to show some
investment (e.g. pain, time, money) to get better
– This can explain some of the proposed effects of treatment
characteristics, individual characteristics and therapist
characteristics.
The role of placebo effects in health
psychology
• Health beliefs
• e.g. pill, herbal tea
• Conditioning effect, reporting error, misattribution process
– Direct effect – physiological change; indirect effect –
behavioural change
• Illness cognitions
– Long lasting disease, medical cause, lifestyle cause
• Health professionals health beliefs
– The doctor may need to believe in an intervention for
it to have an effect
The role of placebo effects in health
psychology
• Stress
– Placebos may function by reducing any stress caused by
illness
– The belief that an individual has taken control of their
illness (perceived control) may reduce the stress response
• Pain
– Pain reduction may be mediated either
• By physiological changes (opiate release)
• By anxiety reduction
– Gate control theory of pain
• Previous experience and expectation also implicated in pain
reduction
Reference
• Gracely, R., Dubner, R., Deeter, W., & Wolskee,
P. (1985). Clinicians’ expectations influence
placebo analgesia. The Lancet, 325(8419), 43.