Genes & Placebos

Genes & Placebos

Your genes may influence whether or not you respond to a fake drug.


Genes and the placebo effect. I'm Bob Hirshon and this is Science Update.

For the first time, scientists have linked a specific gene variant to the placebo effect, at least in one situation. Psychologist Tomas Furmark, of the University of Uppsala in Sweden, says it started as a test of a new drug for social anxiety. Standard procedure requires giving some subjects a placebo, or sham drug, to see if the real one works. Furmark says 40 percent of the placebo group got better.


The clinical effect was as evident as it was in groups that were treated with active drugs.

The groups had different forms of a gene that controls a brain chemical called serotonin. But it's not yet clear how serotonin affects the placebo response. I'm Bob Hirshon for AAAS, the Science Society.

Making Sense of the Research

A placebo (Latin for “I will please”) is a name given to any medicine or procedure with no known medical benefit, at least for the condition for which it's prescribed. A classic example would be a plain sugar pill instead of a real drug. Placebos have been used for at least two hundred years, in cases where a doctor feels that the psychological reassurance of being given medicine would be beneficial enough for the patient.

Placebos also play a key role in medical research. In most clinical trials of a new drug or treatment, some patients are given the real experimental treatment, while others are given a placebo. Neither the patient nor the doctor administering the treatment knows who gets the real thing; this is recorded and tracked secretly by other researchers in the study. In order to be considered effective, the new treatment has to work significantly better than the placebo.

That's an important point, because in almost all clinical trials, some patients who receive the placebo improve. Often, placebos relieve feelings like pain or discomfort, but they can even improve more concrete medical symptoms, like high blood pressure or skin rashes. Patients receiving placebos also report side effects, and these, too, must be compared with side effects from the experimental drug.

The therapeutic power of placebos is known as the “placebo effect.” Scientists have long recognized the placebo effect, but have yet to fully understand it. It seems, though, that the very act of receiving medical treatment can not only make you feel better, but can sometimes help your body heal. Recent studies suggest that the placebo effect may be even stronger than we thought, especially for psychiatric conditions.

So it's not unusual that 40 percent of Furmark's patients with social anxiety disorder responded to a placebo. What Furmark discovered, though, is that patients who responded to a placebo and those who didn't fell into very clear genetic categories. Those who responded carried a particular variant of one gene, which affects a brain chemical called serotonin, a key influence on mood and psychological well-being.

What's more, previous studies had shown that these same genes affect activity in a part of the brain called amygdala, a known center for fear and anxiety. Furmark found that the patients who responded well to the placebo had less activity in the amygdala at the end of the study than they did at the beginning—suggesting that somehow, the gene was allowing the placebo to calm down their brain's fear center.

It's not known exactly how the gene variant does this, or whether this gene variant would make patients respond well to other kinds of placebos. However, this study suggests that some of us may be hard-wired to respond to certain placebos, depending on the medical situation. Eventually, if this could be better understood, it could help researchers design more accurate medical trials, or even identify people who don't need risky drugs to recover from a particular illness.

Now try and answer these questions:


  1. What is a placebo? What role does it play in medical research?
  2. What is the “placebo effect"? How did the genes of the patients in this study influence the placebo effect?
  3. Would you expect that patients who respond well to the placebo would also respond well to the actual treatment? Significantly better? Give reasons for your answer.
  4. Suppose you had a particular illness, and there was a popular drug that could treat it. If a doctor could determine whether or not you were genetically predisposed to the placebo effect for that drug, should the doctor give you a placebo or the real drug? Give reasons for your answer. Would it depend on the circumstances?

Check out the December 26, 2008, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: cleanliness clouds moral judgment, the genetics of the placebo effect, secrets of master impressionists, and more.

For Educators

The National Geographic Magazine resource Please Pass the Sugar offers a brief discussion of the placebo effect.

Understanding Gene Testing, from the Access Excellence website, contains an explanation of various types of genetic testing and their uses.

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