Placebo Effects Flashcards
What is a complimentary therapy?
- A heterogeneous group of therapies that share a focus on, or integration of, treatment of mind and spirit as well as body (Franck et al., 2007)
- Often focus on symptom relief or prevention rather than cure
Give 2 examples of complementary therapies
- Accupuncture
- Aromatherapy
- Cupping
- Herbal Medicine
- Yoga
- Reiki
Complementary therapies are much less researched than mainstream medicine. Does absence of evidence indicate evidence of absence?
- What if complementary therapies show no clinical effects but improve wellbeing.
- i.e. Physical Activity for treatment of depression vs obesity! Evidence base varies hugely.
- Should still be used by indivdual if not doing physical harm, and they are gaining benefit from it in anyway
Why are complementary therapies not widely offered on the NHS
- Can help relieve pain/discomfort
- But limited resources/funding from the NHS- other services more important to fund
- Evidence base weak!
- Available privately
Define a placebo
- Treatment effects of remedies that are not understood to have any direct link to the outcome.
- Placebo effects mimic drug effects (e.g. pain relief).
- Can also mimic drug side effects (e.g. nausea) – nocebo.
- Placebo effects can be very powerful!
Describe the 1996 McQuay systematic review on placebos
- Five placebo-controlled RCTs
- Acute postoperative pain (130 out of 525 had placebo).
- Pain relief measured on scale of 0 to 100%.
- 7% to 37% experienced at least 50% pain relief in the placebo arm (clinical effect)
- 5% to 63% experienced at least 50% pain relief in the treatment arms (still works better)
Define the Van Laarhoven (2015) Systematic review
- 34 trials of chronic itch (due to atopic dermatitis or psoriasis).
- Placebo treatment significantly decreased itch (1.3 out of 10, 95% confidence interval 1.02–1.61) compared with baseline itch (effect size 0.55).
- Placebo effects have a considerable role in these patients’ treatment.
Is the placebo effect;
- Physiological
- Psychological
- Both
Both!
Describe the Finnis 2010 Outcome expectancy psychological mechanism of placebos
- Patients given placebo have expectations of future responses.
- Can be manipulated with verbal cues e.g. by stating whether a treatment is likely to reduce pain.
- Mediates effects in experimental and clinical pain, motor performance in Parkinson’s disease, changes in emotions, and brain responses in patients with drug addiction.
- Placebo effects can be stronger depending on the mode of delivery i.e. IV/Injection/Surgery/Tablets
Describe the Finnis 2010 classical conditioning psychological mechanism for placebo effects
- Repeated associations between neutral stimulus and an active drug (unconditioned stimulus).
- Neutral stimulus elicits response characteristic of the unconditioned stimulus.
- Has been demonstrated in both animal and human studies but difficult to exclude any cognitive component (such as expectation) in human beings.
- More an unconditioned stimulus is paired with a conditioned stimulus, you create a pairing for an outcome i.e. pain reduction.
Describe the neurobiological mechanism involved with the opioid receptors in a placebo effect
- Most research has addressed placebo analgesia.
- Pain related placebo effects can be completely or partly reversed by the opioid antagonist naloxone.
- Confirmed with brain imaging techniques such as PET & fMRI.
- In one PET study, brain changes in response to placebo were reported to be similar to changes seen after with opioid drug.
Describe this:
The middle scan shows there is a neurobiochemical response to placebo treatment, although its not as pronounced as the opioid treatment
Describe non-opioid responses to placebos
- Different placebo mechanisms can be produced depending on the drug used in the conditioning protocol.
- Placebos been shown to change dopamine release in the striatum, basal ganglia and thalamus in patients with Parkinson’s disease.
- Changes in metabolic activity in the brain after administration of placebo in patients with depression.
Out of placebo aspirin and oxygen mask, which showed a larger improvement on a hypoxic high-altitude headache
Larger effect exerted from the oxygen mask- even with placebo the physiological mechanisms were still different.
This means its working at a higher level than just psychological/neurobiological.
What biochemical change was observed with placebo aspirin- hypoxic headache
inhibition of cyclo-oxygenase
Describe what is being observed here
Different mechanisms of placebo link to outcomes.
Conscious expectations can lead to lots of effects which equals a placebo effect being experienced.
Very much effected by the way in which its manipulated i.e. mode of delivery or how we’ve learnt that effect
How many arms should a correct placebo controlled trial have?
Give two of the BCT taxonomies which could be relevant for placebo effects
