Can the placebo effect work in reverse? That is, can a persons belief in the ineffectiveness of a medicine cause it to become less effective or even not work at all?
That would be a form of the nocebo reaction.
I’m not sure about that. The nocebo produces actual (negative) effects from chemically ineffectual substances. I’m asking about a lack of effect from chemically effective drugs caused by the beliefs of the subject.
I read a book where the doctor’s body language could have an effect. Patients were given a real drug, but the doctor believed it was a placebo in some cases. The patients who had the real drug given to them by the doctor who believed it to be a placebo, fared worse than the other groups.
The book was “Bad Science” by Ben Goldacre
There is no reason to suppose that, just because a drug has a “real” effect on some people, it doesn’t also have a placebo effect on other people. Thus, not believing in the drug could reduce its overall effectiveness by removing that part of its effectiveness that is due to the placebo effect. This probably isn’t exactly what the OP has in mind, however… I think the OP is asking whether a “real” pharmacological effect can be counteracted by a negative belief. I’d say possible in some cases but implausible.
That is an interesting idea, though. That even “real” drugs derive some of their benefit through the belief of the subject certainly sounds plausible.
I thought this question was going to be about the cancellation of the placebo effect.
(See http://www.newscientist.com/article/mg18524911.600-13-things-that-do-not-make-sense.html?full=true)
Giving a patient a drug that blocked the effect of morphine along with a saline placebo (instead of morphine) canceled the placebo effect.
Does anyone know of further studies on this (which dates from 2005)?
I have no idea, but I find your question fascinating. I thought you meant the nocebo at first. All I know is the brain is mighty powerful. I wouldn’t disbelieve it if it were the case.
One of the nursing interventions for pain medication involves “selling” the powerful effect of the medication, by telling the patient how powerful it is and how we expect it to affect the pain the patient is experiencing . I always thought this was adding the placebo effect to a real medication.
One thing that supports my asertion is from the Bad Science book. The author cites instances when formerly effective medecines begin to show reduced effectives compared to their former performance when a newer medicine comes along. The old medecine hasn’t changed, but the patients have started to perceive it as being not as good. That is, once something perceived as better is available, they don’t see the old stuff as being that effective anymore. And this is compared to it’s own former performance, not against the new and improved stuff. So this is a little bit towards my question. Just not the complete negation that I was asking about.