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An Introduction to the Placebo Effect
Tagged: Placebo Effect
Julio Rocha do Amaral, MD e Renato M. E. Sabbatini, PhD

When a medicine is prescribed or administered to a patient, it can have several effects. Some of them depend directly on the medicine's pharmacological action. There exists, however, another effect, that is not linked to the medicine's pharmacology, and that can also appear when a pharmacologically inactive substance is administered. We call it placebo effect. It is one of the most common phenomena observed in medicine, but also a very mysterious one.

The placebo effect is powerful. In a study carried out at the University of Harvard, its effectiveness was tested in a wide range of disturbances, including pain, arterial hypertension and asthma. The result was impressive: 30 to 40% of the patients obtained relief with the use of placebo. Furthermore, the placebo effect is not limited to medicines but it can appear with any kind of medical procedure.

http://www.encognitive.com/placebo-e...08-mar-08.html

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In a trial to test the value of a surgical procedure (ligature of an artery in the thorax) to treat angina pectoris (pain in the chest caused by chronic heart ischemia), the placebo procedure consisted in anesthetizing the patient and only cutting his skin. The thus fictiously treated patients showed an 80% improvement while those actually operated upon only 40%. In other words: placebo acted better than surgery.

What is the placebo effect? How can it be explained?

In this paper we shall examine the neurobiological bases of the placebo effect, according to the most recent hypotheses. The study and better understanding of the placebo effect, and its place in medicine, has a great importance for the therapeutical act, besides having great ethical repercussions in medical practice and research. We shall focus our explanations upon a specific type of placebo, the pharmacological agent (medicine). But the principia we discuss in this paper can be generalized to any type of placebo.

What is the placebo effect?

The word placebo comes from the Latin verb "placere", that means "to please".
A good definition is the following:

"Placebo is any treatment devoid of specific actions on the patient's symptoms or diseases that, somehow, can cause an effect upon the patient."

Pay attention to the differencelacebo is an innocuous treatment. Placebo effect is the result obtained by the use of a placebo. A placebo effect is not induced by every placebo. Nevertheless, a placebo effect can only follow the use of a placebo. Did you get it?

The knowledge about the placebo effect was very much enlarged with the medical need to perform controlled clinical trials,a scientific methodology largely used to determine the therapeutic effectiveness of new medicines.
In these trials a placebo is obligatorily administered to a control group of patients, and later the results of this group are compared with those obtained in the group that receives the active medicine, whose action one intends to demonstrate. The bigger the difference in the results between the second and the first groups, the bigger the pharmacological effectiveness of the studied substance.

Very soon these studies made doctors notice that placebos had much more effects upon the studied diseases than anticipated. In some cases the placebo side-effects outreached those of the active medicine...
Consequently, there was a great increase in scientific researches aiming to clarify what is this effect, why does it happen, what is its physiological bases, etc..

Since the placebo effect can be a real one, calling forth beneficial changes in the patient, it can be very useful in clinical practice. The medical ethics code even allow its use.

Types of placebo

Placebos are classified in two groups: inert and actives.

Inert placebo - are those really devoid of any action, be it pharmacological, surgical, etc..

Active placebos - are those that actually have actions, although these actions are not specific to the disease for which they are administered.

What causes the placebo effect?

the videos -
http://ca.youtube.com/prokopton

http://ca.youtube.com/watch?v=obU9J2wETuA