Thread by @TheAmirImani

1/ Forget COVID for a sec! Come read about 🌟𝘱𝘭𝘢𝘤𝘦𝘣𝘰𝘴🌟 instead.

Is placebo effect as powerful as some suggest?
Not really.
But it's surprisingly consistent, & that has important implications in medicine.

I dug up an old student presentation on them.
Let’s dive in🧵

2/ The term was 1st used in medicine in the 1800s: Treatment "adapted more to please than to benefit".

Even then, the importance of suggestion/placebos/bedside manner/whatever you call it was known to be tremendously important.

3/ A famous early Placebo-controlled trial (i.e. comparing the "treatment" to an identical sham) used wooden rods in place of Perkins Tractors, which were metal rods made of supposedly "special alloys".
It showed they were no more effective in managing the advertised disorders

4/ But the idea of a placebo control is much older. The Catholic Church for example used "fake" holy objects in people claiming to be possessed.

If your subject reacted to fake holy objects, you could thankfully remove demons from the differential. 😈

5/ In the 20th century, Pharmacist & Psychologist Émile Coué heavily promoted placebos & "autosuggestion". He'd famously talk up how good his pills were to his patients to boost their effect.

And indeed, placebos were used in everyday medicine until later in the 20th century.

6/ Placebos eventually fell out of favour once there were more discussions of how unethical it was to lie to patients.

Placebo controlled trials became a gold standard in research in the 1960s.

And the 70's-90's boasted some of the wildest studies ABOUT placebos ever.

7/ BLACKWELL (1972)

Take some med students.
Give em blue or red capsules.
Tell em it's either a sedative or stimulant.
It's all placebos (hehehehe)

End:
- 2x likely to report being LESS alert if they got blue.
- 3x as likely to have "severe" effects if they got 2 caps vs 1.

8/ COOPER & BRANTHWAITE (1981)

Women given placebo or Aspirin in either fancy or plain packaging.
Told to take as needed for headaches and record response.

END:
- Expected distribution, but fancy placebos were closer to unbranded ASA in response rate than to bland placebos.

9/ MONTGOMERY & KIRSCH (1996)
Make fake "topical anesthetic"
Make scientific finger torture device
Sign college kids up to test them

END:
- Placebo consistently reduced intensity, unpleasantness, and dimension of painful stimuli to a SMALL but STATISTICALL SIGNIFICANT degree.

10/ CRAEN & MOERMAN (1999)
Now it gets weird.

Meta-analysis of 79 trials of *endoscopy-confirmed* GI ulcers from ’77 to ’94
Compared twice daily vs 4 times daily placebos

END:
4x daily placebo 6-8% more likely to lead to resolution at 4wks (statistically significant).

11/ And more recently?

2013 - Actual vs sham surgery for degenerative meniscal tear.
Sham: Rolled into OR, knocked out, legs moved around, covered in bandages.
Used LKSS scoring scale for benefit.

END:
- Surgery: 21.7 point improvement
- Sham: 23 point improvement

12/ “What else you got?”

- Acupuncture's effect determined by pt's expectations
- Salin inj > capsules > tablets in placebo effect.
- Opposite of placebo effect: nocebo, or negative rxn to inert Rx. often caused by anxiety

I could go on.

13/ “This is interesting, but is it useful?”

I think so!

Lesson 1) The ritual of medicine is important. Not just in the intervention, but feeling safe, heard, and supported has consistent benefit.

Ted Kaptchuk has written and talked a lot about this.

tedmed.com/talks/show?id=…

14/ Lesson 2) Placebo effects can be manipulated, and we need to pay attention to how placebo-controlled trials actually blind their participants.

Also makes comparison tricky. Did you know placebos in antidepressant trials have become more effective?

Walsh et al (2002)

15/ Lots of theories about that^ phenomenon. I think it's because we simply understand depression better. Many older trials were short by today's standards. We have a greater understanding that depression is a long game, and it'll vary over time. Newer trials were longer too.

16/ See below the sources used for the presentation/this tweetorial. Apologies for it being an img. If you have any issues finding a source let me know and I'll try to pull it up.

#TwitteRx #MedTwitter #psychtwitter #Placebo #scicomm