Placebo Effect May Account for Half of Drug's Efficacy

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(Image credit: psyberartist, via Flickr |

Even when a medication works, half of its impact on a patient may be due to one aspect of the placebo effect: the positive message that a doctor provides when prescribing the treatment, according to a new study.

Researchers designed an elaborate study, in which 66 people suffering from migraine headaches were given either a placebo, or a common migraine drug called Maxalt. However, for each migraine attack the participants had during the study period, they were told something different. For example, they were told they were taking a placebo when they were actually taking Maxalt, or vice versa, and sometimes they were told the pill could be either Maxalt or a placebo.

The pain-relieving benefits of the migraine drug increased when patients were told they were taking an effective drug for the treatment of acute migraine. And when the identities of Maxalt tablets and placebo pills were switched, patients reported similar pain relief from placebo pills labeled as Maxalt as from Maxalt tablets labeled as a placebo, according to the study published today (Jan. 8) in the journal Science Translational Medicine. [11 Surprising Facts About Placebos]

The results suggest that the information people have is as important as the effects of the drug in reducing pain, the researchers said.

"In many conditions, placebo effect is a big part of the effect of the drug," said study researcher, Ted Kaptchuk, a professor of medicine at Harvard Medical School. In the new study, 50 percent of the drug's effect could be attributed to the placebo effect, he said

"Themore you give a positive message, the more a drug works. In this case, our message was just as important as the pharmacology of the drug," Kaptchuk said.

In other words, patients may benefit from optimistic messages from their doctors, which may enhance the effectiveness of a good pharmaceutical, the researchers said.

"When doctors set patients' expectations high, Maxalt [or, potentially, other migraine drugs] becomes more effective," said study researcher Rami Burstein, a professor of anesthesia at Harvard Medical School. "Increased effectiveness means shorter migraine attacks and shorter migraine attacks mean that less medication is needed," Burstein said.

However, physicians should be realistic when prescribing a treatment, Kaptchuk said.

"The medical community should consider what's the positive message that is still accurate, and not an exaggeration that verges on deception," he told LiveScience.

Same drug, different expectations

Migraine attacks are throbbing headaches, usually accompanied by nausea, vomiting and sensitivity to light and sound. The researchers decided to look at migraine, because it is a recurring condition, and responds well to medication, Kaptchuk said.

During the study, the participants had a total of 450 migraine attacks. Each time they were provided with one of the six available treatments: two were made with positive expectations (envelopes labeled "Maxalt"), two were made with negative expectations (envelopes labeled "placebo"), and two were made with neutral expectations (envelopes labeled "Maxalt or placebo").

But within each of these conditions, the envelopes contained either the placebo or Maxalt. The patients then reported their pain experiences.

"When patients received Maxalt labeled as placebo, they were being treated by the medication — but without any positive expectation," Burstein said.

For both placebo and Maxalt, patients reported great pain-relieving effects when the envelope was labeled "Maxalt." This suggests that a positive message and a powerful medication are both important for effective clinical care, the researchers said.

Bodily memories

The placebo effect is centered on the idea that a person’s expectations and beliefs drive changes in symptoms, even though they have received a sugar pill or a sham treatment with no effect. Knowing that they have received a placebo changes their expectations, which is expected to alter the placebo effect.

However, people in the study also reported pain relief even when they knew the pill they were receiving was a placebo, compared with no treatment at all.

This finding "contradicts the medical beliefs," Kaptchuk said. "Because in medicine, we think you have to think it's a real drug for placebo to work. But apparently, the body has memories, or an embodied awareness, which operates below the level of consciousness."

One possible mechanism for this effect could be that the body is conditioned to react positively in medical situations, Kaptchuk said.

"We know from other studies that the symbols, the rituals and the words of medicine activate the brain to release neurotransmitters that change the experience of illness. It activates centers in the brain that modulate many symptoms like pain and nausea and fatigue," he said.

Email Bahar GholipourFollow us @livescience, Facebook & Google+. Original article on LiveScience.

Bahar Gholipour
Staff Writer
Bahar Gholipour is a staff reporter for Live Science covering neuroscience, odd medical cases and all things health. She holds a Master of Science degree in neuroscience from the École Normale Supérieure (ENS) in Paris, and has done graduate-level work in science journalism at the State University of New York at Stony Brook. She has worked as a research assistant at the Laboratoire de Neurosciences Cognitives at ENS.