Pain Patients Respond Differently to Placebo Effect

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Studies involving people who suffer from chronic pain often give some of them placebos to show whether the treatment has real value. Little is known, however, about the types of people who tend to respond positively to placebos, a mystery that places a hurdle before researchers who want to learn the best way to treat people’s pain.

A new study by researchers at the University of Michigan Health System sheds some light on one group of people that seems to experience the placebo effect. The researchers found that people with one type of chronic pain who have greater swings in their pain fluctuations tend to be more likely to respond to placebos.

“There is substantial evidence that the placebo effect has strong biological underpinnings, and that some individuals are more likely than others to demonstrate this effect,” says Daniel J. Clauw, M.D., director of the U-M Chronic Pain and Fatigue Research Center.

“This study suggests that individuals with greater hour-to-hour and day-to-day variability in their pain may be more likely to be placebo responders,” says Clauw, senior author of the paper.

Each of the 125 participants in the study carried a Palm-based electronic diary and was prompted at random intervals to record his or her pain level. Participants were prompted on average about three and a half times per day. The patients who were enrolled in a multicenter drug trial of the anti-depressant milnacipran versus a placebo. Some of the participants experienced a large range of pain variability, while others experienced pain at fairly constant levels.

Those whose pain levels varied widely were more likely to respond to the placebo. They were not, the researchers found, necessarily more likely to respond to milnacipran, which suggests that high pain variability may be a predictor of a placebo response.

MEDICA.de; Source: University of Michigan Health System