The placebo effect seems to make little sense: get ill, take a dummy pill, and you'll recover in much the same way as someone taking real drugs. While there have been many theories bandied about over the years to explain how it works, new evidence suggests that it may be genetic.


A team of researchers at Boston's Beth Israel Deaconess Medical Center and Harvard Medical School has published a study in PLoS One that identifies the first ever genetic difference between patients who respond to placeboes and patients who don't. If it's correct, it could completely change the way drugs are tested and prescribed.


The study looked at patients with irritable bowel syndrome who were enrolled in an acupuncture trial. Split into three groups—one that received no treatment, one that got fake acupuncture with little interaction with the caregiver, and another that received fake acupuncture with real interaction—they were also analyzed genetically.

The results show variations in the COMT, or catechol-O- methyltransferase gene, affect patient response to placebo. The gene is known to be related to dopamine release—a neurotransmitter associated with reward and positive feeling—and the study shows that variations in it are strongly correlated with placebo susceptibility.

Of course, many of the usual caveats apply: this was a modestly sized study, involivng just 104 patients, which considered just one placebo treatment used for one medical condition. If, however, the results bear out, then expect to see genetic tests being used to improve both personal care and clinical trials in the future. [PLoS One via Geekosystem]

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