But everything about placebos is controversial and fascinating, and the etymology is no exception.

The most common funeral rite of the Middle Ages began “Placebo Domino in regione vivorum” – “I shall please the Lord in the land of the living”. The rite itself became known as the Placebo, and those involved as placebo-singers.

At some point “placebo-singer” acquired an ill reputation and became used as an insult. In Canterbury Tales, Chaucer writes: “Flatterers are the devils chaplains, that sing ever ‘Placebo'”. And during the English Civil War, a cleric was described by one of his enemies as “a placebo singer at Lincoln’s Inn, and afterwards a turncoat at Bridgefoot”. An 1822 dictionary of proverbs defines “to sing placebo” as “to endeavour to curry favor”.

There are a couple of explanations of how exactly this came to be. I think the most likely is a sort of intersection between the old term “to sing placebo” as in a funeral, and the literal meaning “I will please” – thus someone who “sings placebo” gradually shifts from someone who literally sings a hymn to somebody who tries to please, sort of as a pun. One modern sort-of equivalent that comes to mind is the use of “gaylord” as a playground epithet for gay people because it sounds like it should mean that, even though originally it was a given name derived from the French name Gaillard.

A second theory says that it was meant as a sort of insult to priests, who were always saying incomprehensible things to impress the overly credulous. This one doesn’t strike me as very believable, but it’s worth noting that another priestly Latin saying, hoc est corpus meaning “this is my body”, might through a similar process have mutated into the word “hocus pocus” meaning “a dumb attempt at magic for the gullible”. But this is just as convoluted an etymology as placebo, and probably not much stock should be placed in it – though reading that article did teach me about a Norse demon I didn’t know about before, so it wasn’t a total loss.

A final theory, maybe the most interesting, is that unscrupulous people would show up at random funerals, sing the placebo with everyone else, and loudly mourn the deceased – intent on demanding a share of the post-funeral feast afterwards. As such, placebo-singer came to mean not only flatterer, but imitator or phony – with obvious implications for the medical usage. Wikipedia seems convinced of this one, but there’s no source cited and I can’t find it in any primary.

At some point in the late 18th or early 19th century, it became associated with medicine, although it’s not clear exactly how. It seems to have had the sense of a popular but not very effective treatment, either derived from the placebo singers of above or from an alternate translation of placere, “to be popular”. Compare to the word “nostrum”, which is the Latin word “ours” and indicates popularity without a whole lot of effectiveness in a very similar way. This is the British Medical Journal‘s position on the matter – at least in 1999. A 2013 update makes a counterargument from Latin grammar – why isn’t the name the more appropriate third-person “placebit”, meaning “it will please”? 18th century doctors were generally grim people who spent their days watching people die of cholera. They wouldn’t have come up with some cutesy word where the pill is depicted as talking about itself. So maybe it comes from the funeral rites after all.

Annnnnnnnnyway, this whole line of thinking started as a way of procrastinating on the research I should be doing: trying to figure out what the heck is going on with placebos in depression. Asbjørn Hróbjartsson, who presumably studies biostatistics in between quests to slay frost giants, finds minimal evidence of placebo effects anywhere, and particularly cites three studies on depression that found no difference between a placebo and an untreated group. Wampold et al disagree and reanalyze the data to find placebo effects in a couple places, but they’re not very impressive and Hróbjartsson is definitely not impressed.

Most antidepressant studies parrot the conventional wisdom that the d=1.5-or-so effect size of antidepressant treatment consists of a placebo effect of 1.0 and a drug effect of 0.5. But there is hardly any attempt to think critically about the placebo part. How do we know it’s a drug placebo effect, and not just depression getting better on its own if you wait long enough, or people feeling special and liked because someone is doing a study on them?

Irving Kirsch is the only person I have seen even try to address this, and his methodology is audacious to say the least – comparing no-treatment arms in psychotherapy trials to treatment arms in totally different pharmacology trials. He finds that about 2/3 of the apparent placebo effect is indeed due to a drug placebo effect and 1/3 to people-eventually-get-better. The question is whether we want to trust him over Hróbjartsson’s small but more focused trials finding no drug placebo effect.

This is pretty important because there are a lot of depressed patients for whom the benefits of antidepressants might not be worth the costs, or who just don’t want to take them. If the VERY LARGE observed placebo effect in depression is in fact a real pill-based placebo effect, then it becomes vital to get some pill into these people right away. Folic acid, which has enough evidence as a depression treatment to be believable but which is also dirt cheap and very safe, would be a good choice.

But if drug placebo effects don’t do anything and it’s just people getting better over time, then it’s not worth pushing folic acid or whatever quite so hard.