Placebo Flashcards
Definition of placebo
Control treatment with similar appearance of drug but without it’s specific activity
What two groups are in a two arm trial?
Three arm trial?
Two arm trial:
Placebo group
Treatment group
Three arm trial:
Untreated group
Placebo group
Treatment group
Placebo paradox?
Placebo in RCTs obscure treatment effect, they’re a nuisance and non-specific
VS
Placebo in Clinical Practice is useful and is a good clinical practice because it involves factors other than specific treatments
Does placebo play a bigger role in acute pain or chronic pain?
Chronic pain
Why is pain multidimensional?
- Pain has negative effect on Cognition and Emotion
- Emotion can affect Cognition and Pain positively or negatively
- Cognition can affect Emotion and Pain positively or negatively
3 influences on the placebo effect
- vPatient-Practitioner Interactions
- Psychological Mechanisms
- Neurochemistry
How can a patient be informed about pain?
How much pain to expect
Cause of pain
How to deal with pain
Positive/Enthusiastic doctor
What is a contextual factor that can influence placebo? Which one decreases pain?
Open Injection (decreases pain)
vs
Hidden Injection
What are the three steps to pharmacological conditioning? What do they involve?
- Pre-conditioning : Unconditioned stimulus and Neural stimulus separately
- Acquisition : Unconditioned stimulus + Neural stimulus
- Evocation : Conditioned stimulus
Does Opioid Conditioning + Expectation Placebo involve endogenous opioids?
What about non-opioid conditioning?
Yes
No
Non-opioid conditioning placebo is mediated with what receptor? Which antagonist what used to show this?
CB1
Rimonabant
Placebo effect by conditioning with opioids involves ___________
Placebo effect by conditioning with non-opioids involves __________
endogenous opioids
endocannabinoids
What is the effect of branding of headache pain?
ORDER OF EFFECTIVENESS: Actual aspiring w/ branding Aspirin w/ no branding Branded placebo Placebo Nothing
Clinical example of how placebo activates endogenous opioid system?
u-opioid radiotracer was given by I.V.
Pain was administered
Gave placebo and took PET scans
MOR activity correlated w/ reduction in pain
Example of how placebo activates dopaminergic circuit?
Thermal stimulus to give pain
Placebo and Lidocaine given topically
PET scan tracks dopamine radiotracer
Change in dopaminergic activity correlated w/ placebo administration
Morphine + saline in mice : what response?
What about morphine + naloxone?
Placebo effect
Blocking of placebo effect
Aspirin (non-opioid) + saline : what response?
What about aspirin + naloxone?
Placebo effect
Placebo effect (no decrease by introducing placebo blocker)
What is nocebo?
Info stating that procedure will be painful leads to increased pain response
Example of psychological induction of pain?
Placed electrodes on peoples heads
Told them there would be an electric current that passes them
Headaches were reported
Nocebo involves release of what?
What antagonist blocks this?
Cholecystokinin
Proglumide
When blocking cholecystokinin with proglumide, what is the response in hidden injection vs. open injection?
Hidden : no changes in pain
Open : Pain increases when given saline but proglumide decreases it
