Placebo gene discovered9th December 2008
A genetic basis for susceptibility to the placebo effect has been proposed.
While the experiment involved only a small number of people, the results help explain the ability some people have of benefitting from false cures.
It is still possible that the isolated gene only has an effect upon some human conditions and responses to treatment.
The finding is the first ever link to be drawn between the placebo effect and a specific gene.
The finding will have a marked effect upon pharmaceutical research, because the placebo effect often mars the results of clinical trials.
Tomas Furmark of Uppsala University in Sweden said that he and his researchers believe it is the first time anyone has linked a gene to the placebo effect.
Furmark and his research team recruited 25 people with an exaggerated fear of public humiliation, also known as social anxiety disorder (SAD).
The researchers gave the participants in the study two months of treatment consisting of a placebo.
Both the participants and their doctors were unaware that the treatment was not a real pharmaceutical. At the beginning and the end of their treatment, participants gave a speech.
Ten volunteers responded to the placebo and improved their ability to speak in front of others. By the end of the experiment, the ten subjects were much calmer than the others. The other anxiety scores had remained the same.
Throughout the study, Furmark and his team made records of the neurological activity of the participants.
Brain scans of the ten participants showed that activity in parts of the brain associated with emotions of fear had gone down by 3%.
Furmark and his team then began to investigate whether there were genetic differences between the two groups of participants.
The researchers scanned for people with two copies of a particular variant gene that influences serotonin production.
Previous research had shown that people with two copies of this gene are less anxious in general. Of the people unaffected by the placebo, none of them had two copies of the variant "G" gene. Of the 10 who experienced a response, eight were found to have two copies of it.
The same gene may have an effect upon other disorders in which the fear centers of the brain play a role. Such conditions would include pain disorders, phobias, and depression.
Furmark warns that only further studies will reveal the influence of genetics upon the placebo effect.
Fabrizio Benedetti of the University of Turin said that there are many different ways in which the placebo effect can express itself, and that the expectation of a reward can also cause a placebo reaction.
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Title: Placebo gene discovered
Author: Luisetta Mudie
Article Id: 9464
Date Added: 9th Dec 2008