In placebo-controlled double-blind clinical trials, the placebo could have an effect on studied patients (10%, 15% or even more), even if the tested drug is the molecule of concern.
The effect of placebo could be due to its bioactive constituents. However, it is mainly psychotherapeutic.
Hi Thanks for your responses. For Roland and Vinay, psychology could play a role, this not the case for Jonas and N.US. I Think it's hard to prove scientifically the effect of psychology on the patient's reaction. Giving a placebo to the patient and making him believe that it is the active drug could explain his positive reaction ! How ? Are there secreted molecules ?.
I think its all psychological hypothesis: it's all in some ones mind. The psychological explanation seems to be the one most commonly believed.
Yes, when there is no real standard treatment and one group is given the active treatment and the other group is given nothing there could be psychological effects in the patients just because they either know they are getting/not getting the drug. To avoid this a placebo, which is an inert pill which looks, smells and tastes just like the active drug is given to the control group.
Yes, when there is no real standard treatment and one group is given the active treatment and the other group is given nothing there could be psychological effects in the patients just because they either know they are getting/not getting the drug. To avoid this a placebo, which is an inert pill which looks, smells and tastes just like the active drug is given to the control group.
The placebo effect (see definition by Vinay) seems to be a kind of automatic learning procedure of the brain involving changes of activity in particular electric circuits (possibly originating from the frontal cortex). Psychologically this results in strong believe.
Recently the placebo effect has been defined as beneficial physiological or psychological changes associated with the application of an inert substance, sham procedure or treatment known to be without any therapeutic effect for the specific condition being treated, or in response to therapeutic encounters and symbols. It is clear that the placebo effect is not because of the inertness of the treatment. it includes complex phenomena encompassing individual patient and therapist characteristics, features of the patient-clinician relationship (e.g. beliefs, expectations), and attributes regarding the setting and environment in which the treatment is carried out. Indeed, the study of the placebo effect examines the psychosocial context surrounding the patient and the impact that this context has on the patient’s experience and clinical outcomes.
Dear Jan. Here are some of the references that helped to build up this definition
Best regards
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3. Kaptchuk TJ, Kelley JM, Conboy LA, et al. Components of placebo effect:
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effect:Recent advances and current thought. Annu Rev Psychol 2008; 59:
565-90.
6. Wilentz J, Engel L. The research and ethical agenda. In: Guess HA, ed. The
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:757-762.
8. Finniss DG, Kaptchuk T, Miller F, Benedetti F. Biological, clinical and ethical
advances of placebo effects. Lancet 2010; 375: 686-95.
Hello Jorge, Thanks a lot for these interesting references. Do you think I will find a response to my question: Is there any known secreted molecule which could explain the effect of placebo ?
Hi,
It's not just about a single molecule. Have a look at the excellent review by Prof Irene Tracey in Nature Medicine: http://www.nature.com/nm/journal/v16/n11/abs/nm.2229.html
Common, why not looking up Wikipedia and go from there?
http://en.wikipedia.org/wiki/Placebo
Best, Dan
Although placebo effect has been studied extensively, there is no clear consensus regarding its mechanism. Placebo analgesia has been seen to reduce activity in the pain processing areas of the brain. Another view is that there is some amount of ''conditioning' and 'expectation' involved. Dopamine may be involved here. Yet another view is that placebo effect, especially placebo analgesia, is mediated via the opioid pathway by the release of endorphins. This view is endorsed by the studies showing that opioid antagonist, Naloxone, can reverse this endorphin mediated placebo analgesia, to an extent.
It is important to make some sort of distinction between a control (which may or may not be inert) and the placebo (or nocebo) effect which occurs due to the context of the interaction (experiment, trial, consultation etc.) and in addition to any biological activity of the treatment or control.
It has been clearly demonstrated that the "placebo effect" has a distinct neurobiological substrate.
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