Providing a subject is not informed, a placebo has a positive effect on around 30% of subjects for most conditions. According to some studies on the effectiveness of anti-depressives, placebos have an equal effect, say, to that of Prozac.
That shouldn't take anything away from Prozac, particularly in light of the following...
I want to know if any studies have been done on the 'Inverted Placebo' effect, that is, where subjects are given a real medication and told it is a placebo. I suspect that for conditions that require self assessment the effectiveness of medications will fall by more than half.
For a fair study one should choose a non-life threatening condition that can be objectively assessed. One group of subjects should be given the active medication and told it is a placebo, another group given the placebo and told that it is the active medication, a third and forth group given placebo and active medication respectively and informed correctly of the medication they are receiving, and a fifth group given medication and placebo double blind - neither the patient nor the administrator of the medication being aware of which is the placebo and which isn't.
So why should we play games with people in this seemingly unkind way?? Let's think back to the Prozac. If the effectiveness of a placebo is enhanced by the belief of a subject (believing that it is active) and if the effectiveness of active medication is compromised by a belief that it is a placebo, and if these effects are not symmetrical, then any double blind test will have results skewed in a predictable manner (if the amount of skewing is known.)
Let's consider an actual example. Let's give the real medication administered to a person who thinks it is real an effectiveness value of ONE; the real medication given to a patient who suspects that it is a placebo has an effectiveness 30%; a placebo given to a patient that thinks it is the real medication an effectiveness value of 60% and thinking that the placebo is inactive an effectiveness of zero.
If 50% of subjects receive the placebo and 50% think they may have received the placebo, then we have (100 subjects total, double blind test) 50 placebo, 15 report effectiveness (30%) 50 Active, 32.5 report effectiveness (65%)
In this example we assume that 100% of those getting the active medication and who think they are getting the active medication report an improvement. We are also assuming that exactly half of those who are treated will think they are receiving the active medication.
Would this be the same in a population of depressed patients? A symptom of depression is a negative outlook - change the ratio to more thinking they have received the placebo and results would be further compromised and require considerably greater correction.
But has anyone done the 'Inverted Placebo' experiment to establish if a negative belief has a similar negative effect to that of the positive effect of a positive belief?
Inverted Placebo is a better name, but you have to be first!! 'Nocebo' is the little known term given to the inverted placebo effect i.e. the effect that negative expectations have on a medication.
In article: The Nocebo Effect: Scattered studies suggest that negative thinking can harm patients’ health. By Gardiner Morse "The medical literature is replete with clinical research documenting the placebo effect. In fact, the concept is so well established in Western medical thinking that few physicians would challenge it; of course a patient’s positive expectations about an intervention can positively affect outcome. But what about a patient’s negative expectations? Can negative thoughts harm health? There’s a small but suggestive body of literature to support the idea, and a little-known term to describe it: the “nocebo effect.”"
Full Text at http://www.hippocrates.com/archive/November1999/11departments/11integrative.html
Also see 'Nocebo Effect' May Explain Some Drug Side Effects http://www.celebration.md/news%20stories/nocebo%20effect.htm
Placebo's Evil Twin -- The Nocebo Effect http://www.mercola.com/2002/may/18/placebo_nocebo.htm
Kind Regards, Robert Karl Stonjek.
PS how come you lot didn't write in and tell us about this effect? Don't sit on your hands - pointing out my flaws and inadequacies can be an enlightening and entertaining pursuit as I'm sure members so engaged will attest...
© Robert Karl Stonjek 2002