Not all placebos are created equal, according to a new study. In a rare trial pitting two fake treatments against each other, researchers have found that a sham acupuncture technique provided more pain relief than a dummy pill. The two nontreatments also caused different "side effects."
Placebo effects have been reported with pills, injections, and even surgery. Previous research hinted that some treatments might elicit stronger placebo effects than others, but the idea hadn't been rigorously tested, says Ted Kaptchuk, the researcher at Harvard Medical School in Boston who led the current study.
Kaptchuk and colleagues recruited 270 people with repetitive strain injuries (such as the aching arm that results from pushing a computer mouse around a desktop day after day). Half the volunteers took a cornstarch pill once a day; the rest received a fake acupuncture treatment twice a week. Both groups were told they would receive either a placebo or real treatment during the trial and that they could receive real treatment afterwards free of charge. The needles used in the procedure looked identical to real acupuncture needles, but the point retracted into a hollow shaft instead of penetrating the skin. The vast majority of people can't feel the difference between the sham procedure and the real deal, Kaptchuk says.
People in both groups reported less pain after two weeks of treatment, Kaptchuk and colleagues reveal in the 1 February issue of the British Medical Journal. But in the following weeks, those who continued with the sham acupuncture experienced greater pain relief than those who stuck with the bogus pills. Kaptchuk suspects that the increased doctor-patient interaction in the acupuncture group--or possibly the procedure's mystique--may account for the difference. "It tells us that the ritual matters in health care," he says. The team also found that patients in the two groups reported side effects similar to those they'd been told to expect, including pain during and after treatment in the acupuncture group and drowsiness and dry mouth in the pill group. "We had people [taking the pills] calling up, too groggy to get out of bed," Kaptchuk says. Three patients in the pill group even withdrew from the study due to side effects.
The work provides an interesting illustration of how patients' expectations influence the outcome of treatments, says Leora Swartzman, a psychologist at Western Ontario University in London, Canada. But George Lewith, a clinical researcher at the University of Southampton, U.K. says the sham acupuncture technique may not be sufficiently fake. Certain Japanese acupuncture techniques also involve light taps to the skin without penetration by needles, Lewith says. Kaptchuk counters that such techniques haven't been shown to have any physiological effect, and he sticks to his conclusion: There's a real difference between bogus treatments.