Placebo, (genetic) Matter Over Mind

Thursday, December 20, 2012
By Wolfgang K Piller MD

Placebo in medicine means that a drug or treatment is effective although it is not designed to be. It plays an important part in research because something ineffective is being compared to a new drug or treatment to see, whether there is a beneficial difference, thus proving that it works.

Some people are more likely than others to respond to placebos. It is not simply the result of an individual’s ‘imagination,’ the response stems from measurable chemical changes in the brain. Now a study has investigated a group of patients with irritable bowel syndrome and treated them with sham acupuncture plus supportive interaction (augmented-placebo), sham acupuncture alone (limited-placebo) or no treatment at all (waiting list, no-placebo). Relief of IBS symptoms was greatest in the augmented-placebo group, intermediate in the limited-placebo group, and least in the waiting list group as would be expected.

Then the investigators looked at certain genes, which are important in the dopamine metabolism in the brain. Dopamine lifts our sensation of well-being and interestingly study participants who had a certain variation of the gene from both parents had the greatest response to a placebo, those with one copy had intermediate responses, and those with no copies responded to neither type of placebo. The genetic variations had no effect on outcomes in the wait-list group. In this study, about one quarter of patients had two copies of the gene, one half had one copy, and one quarter had no copies (thus following the simple inheritance laws which Mendel discovered already in 1866.) Although further trials are necessary this small study shows that an inherited biological variation affects a person’s response to a placebo and it enhances the understanding of the placebo response. In the future, investigators who design trials might want to consider genotyping participants, to be sure that results are not skewed by unusually high or low numbers of participants who are biologically more likely to experience placebo responses.

However this finding might have further far-reaching consequences. Dopamine plays an important role in the so-called reward (or you could call it pleasure) system, which again is important in understanding addiction. Positive reinforcement shows a person that his behaviour rewards him, thus it keeps addiction alive. It is known that addiction is more likely to run in families; therefore it would be interesting to know whether this variation of the investigated gene is responsible for addiction, too. (By the way the brain does not ask for alcohol or heroin or nicotine or food, because it does not know what those things are, it only demands ‘that stuff,’ that has been lifting those pleasurable dopamine levels in the past.)

Additionally, placebo is nothing else but manipulation, because it only makes you believe that something makes you feel better without really objectively doing so. This could have a major impact in our shopping behaviour, lifestyle choices, voting, etc. because doing something a certain way makes your dopamine levels rise and you feel good. May be a scientist or a lesser mortal being already knows the answer. I guess they know, because in medicine we call it placebo and in life psychology.

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