4 - Placebo effect

Placebo effect

When a substance or procedure produces a response due to expectations or beliefs, rather than its physical or chemical properties

What treatments and procedures can have a placebo effect?

• Wide ranging: from drugs to surgery to psychotherapy

• Not strictly a psychological response!

• Active “scientifically proven” treatments (e.g., Tylenol, Morphine) also contain placebo effect in addition to their pharmacological effects.

What affects the strength of a placebo effect?

1. patient characteristics

2. social norms

3. situational demands

4. provider behaviour

What patient characteristics can affect the strength of the placebo effect?

• NO placebo-prone personality, but…

  • Age (sex doesn’t seem to matter)

  • Greater need for approval

  • Hypnotic Suggestibility

  • Higher Anxiety

  • Optimism

What social norms affect the placebo effect?

• Canadians spend more than $30 billion each year on drugs

  • Average household spends $1000/year on prescription drugs

• If you’re sick, take a drug, you’ll get better.

What situational demands can affect the strength of the placebo effect?

• Medical formality (medications, machines, uniformed personnel) will induce stronger placebo effects

 

• Shape, size, colour, taste and quantity of the placebo influences

 

• the more a drug seems like medicine, the more effective it will be

 

Ex. red, green and yellow associated with stimulants, whereas blue and green are associated with a sedative.

Ex. stronger effect in injections > pills > tablets, larger pills, higher number of pills, brand-name.

What provider behaviour can affect the strength of the placebo effect?

• Is provider warm, confident, empathic? Competent?

• Does provider convey they think treatment will work?

 

Ex. verbal suggestions and behaviours

What are the 3 theories of how the placebo effect works?

• Expectation --> Positive expectations or beliefs that the treatment will work

 

• Endorphins (particularly in context of using placebos for pain)

 

• Classical Conditioning (particularly in context of using placebos for pain)

  • physiological response due to past experiences

In a study at Yale giving two packages of the same ice cream, they found that the indulgence imaging led to …

bodies thought it was greater calories (decreased Ghrelin) Versus "guilt-free" packaging

What is the current model of testing between placebo and treatment?

• Current model of research sets up a competition between the placebo and the treatment, as to outperform it.

  • If the drug does pass the effect --> the placebo is considered irrelevant

  • If the drug doesn't pass --> placebo is labelled as the villain

• With this, we ignore that the backbone of every drug/treatment is built up from both the placebo AND the drug.

In a study where the doctor gave patients a skin prick test, and measures the bump; then applies a placebo cream, the additional statement of __________ made the rash better

this a anti-histamine cream and it will make it better

In a study where the doctor gave patients a skin prick test, and measures the bump; then applies a placebo cream, additional ___________ made the placebo affect even stronger

High warmth and competence

According the video on the placebo effect, the place effect is made up of:

• Body's natural ability

• Mindset ("better" "worse")

• Social context (warmth and competence)

Nocebo effect

When a substance or procedure produces a NEGATIVE response (negative symptoms, adverse effects) due to negative expectations or beliefs, rather than its physical or chemical properties

In a meta-analysis of 12 RCTs of vaccines, they found that in the first dose, there was …

Very similar rates of side effects between the placebo versus active treatment

In a meta-analysis of 12 RCTs of vaccines, they found that the nocebo effects accounted for…

76% of the systemic side effects (i.e. headache, fatigue), and 25% of more local events (i.e. swelling and redness)

In a meta-analysis of 12 RCTs of vaccines, they found that in the second dose, there was …

• Much wider spread of side effects between placebo and treatment groups

• More side effects in the first dose --> primed to show/expect more side effects in the second.

What is responsible for the nocebo effect?

• Expectations of adverse events (ex. negative expectancy)

• Stress and Anxiety

• Misattribution of routine background symptoms

Non-deceptive placebo

Communicating to participants what placebos are, explaining the science behind how they work, and highlighting how placebos can still provide beneficial effects even if people know they are taking them

• Leverage expectancy effect

In a study on non-deceptive placebo, and emotional distress, they aimed to:

determine whether a non-deceptive placebo could actually reduce emotional distress (self-report and EEG).

 

• Control group (a salt nasal spray & read on pain), and nondeceptive placebo group with (a salt nasal spray & description of how placebo works)

• Watched different images that would invoke different emotional responses

In a study on non-deceptive placebo, and emotional distress, they found …

• Reported less distress if they were in the nondeceptive placebo group

• Lower EEG processing if they were in the nondeceptive placebo group.

Effects of placebo treatment should not be thought of as either a medical trick or a purely psychological phenomenon, but that it:

• Achieves success in the absence of effective therapy

• Reduces substantial pain and discomfort

• Continues to account for significant portion of medicine’s effects today

• Increases effects of only modest treatment approaches

What are the clinical implications of nocebos?

Reporting of adverse events is necessary and ethical but may prompt/increase nocebo responses!

• Disclosure and education about nocebos in informed consent

• Highlight probability of NOT experiencing adverse events