Placebo

Question 1

Placebo

Answer 1

Placebos are pharmacologically inactive
The placebo response rate is usually low for patients with mania, schizophrenia, and psychotic depression
In cases of mild and moderate depression the placebo effect can be over 30%
Inert placebos can have adverse effects
Placebo induced analgesia can be blocked by naloxone (suggesting placebo effects can be mediated by biological mechanisms)

Question 2

Placebo sag

Answer 2

Placebo sag refers to a situation where the placebo effect is diminished in people who have previously experienced multiple treatment failures.

Question 3

Placebo

Answer 3

Placebo is not the same as no care (patients who maintain contact with services have a better outcome than those who receive no care)
The placebo response is greater in mild illness
The higher the placebo response rate the more difficult it is to power studies to show treatment effects
It is difficult to separate placebo effects from spontaneous remission
Patients who enter RCTs generally do so when acutely unwell. Symptoms are likely to improve in the majority irrespective of the intervention (so called ‘regression to the mean’)
The placebo response rate in published studies is increasing over time
‘Breaking the blind’ may influence outcome. The resultant ‘expectancy effect’ may explain why active placebos are more effective than inert placebos.
Not all placebos are the same. Colour, route, branding all influence the placebo effect
Placebo response is usually short lived