WEDNESDAY, Dec. 22 (HealthDay News) -- Confronting the "ethically questionable" practice of prescribing placebos to patients who are unaware they are taking dummy pills, researchers found that a group that was told their medication was fake still reported significant symptom relief.

In a study of 80 patients with irritable bowel syndrome (IBS), a control group received no treatment while the other group was informed their twice-daily pill regimen were placebos. After three weeks, nearly double the number of those treated with dummy pills reported adequate symptom relief compared to the control group.

Those taking the placebos also doubled their rates of improvement to an almost equivalent level of the effects of the most powerful IBS medications, said lead researcher Dr. Ted Kaptchuk, an associate professor of medicine at Harvard Medical School and Beth Israel Deaconess Medical Center.

A 2008 study in which Kaptchuk took part showed that 50 percent of U.S. physicians secretly give placebos to unsuspecting patients.

Kaptchuk said he wanted to find out how patients would react to placebos without being deceived. Multiple studies have shown placebos work for certain patients, and the power of positive thinking has been credited with the so-called "placebo effect."

"This wasn't supposed to happen," Kaptchuk said of his results. "It really threw us off."

The test group, whose average age was 47, was primarily women recruited from advertisements and referrals for "a novel mind-body management study of IBS," according to the study, reported online in the Dec. 22 issue of the journal PLoS ONE, which is published by the Public Library of Science.

Prior to their random assignment to the placebo or control group, all patients were told that the placebo pills contained no actual medication. Not only were the placebos described truthfully as inactive pills similar to sugar pills, but the bottle they came in was labeled "Placebo." Health care providers also spent about 15 minutes explaining how placebos can have powerful effects and that a positive attitude, while not essential, could help.

At the end of the study, which was funded by the National Center for Complementary and Alternative Medicine and the Bernard Osher Foundation, 59 percent of the women in the placebo group reported adequate symptoms relief, vs. 35 percent of the control group.

"Some patients were very disbelieving, some were very enthusiastic, but by the end many really enjoyed themselves," Kaptchuk said. "They felt empowered."

He theorized that the very ritual of taking pills to treat illness -- even fake ones -- initiates a brain response that changes the way patients perceive and experience their symptoms.

"There's nothing that's not in our heads," Kaptchuk said. "Our emotions, sadness, anxiety, all interact with our symptoms."

Dr. Andrew Leuchter, a professor of psychiatry and biobehavioral sciences at the David Geffen School of Medicine at UCLA, noted the research indicates that patient ignorance of their placebo treatment may not be necessary to achieve results.

"It's a very interesting study and, I think, a very clever design," said Leuchter, also vice chair of UCLA's academic senate. "Part of this could be a conditioned response."

Leuchter noted that research participants typically don't want to disappoint investigators, which could also have contributed to their perceptions. Also, those placed in the control group may have been disappointed not to receive placebos, which could account for some of their reactions, he said.

"I think we want to see how long-lasting this improvement would be," Leuchter said. "If we follow the subjects for a couple of months, do the benefits last?"

The study authors noted that the finding would need to be confirmed with a larger trial. For his part, Kaptchuk said he hopes to study long-term effects in future studies, as well as patients with various other illnesses.

"This is a very preliminary, first-step study," he said, adding that the small size of the trial group was a limitation. "I think the ethical question was a very important component."

More information

For more information on the effect of placebos on certain illnesses, visit the archives of the American Psychological Association.