In a trial of drugs for heart disease, one group who took their drugs regularly, as directed were 40% less likely to die than those who did not.
The catch? Both of those groups were taking placebos. From NeuroSkeptic
What the placebo adherence effect demonstrates is that there may be confounds no-one has thought of. They might even be impossible to measure. And if these mystery confounds can literally kill you, they can probably cause all kinds of other effects too.
The patients were corrected for every health and lifestyle factor they could think of. So there must be a cause, we just have no freakin’ clue what it is.
Placebo effect, you win this time …