WEDNESDAY, Feb. 16 (HealthDay News) -- Everyone's heard of the placebo effect: when you take a sugar pill but believe it is medicine, it tends to work. Now a new study suggests that the opposite may also be true.
In the study, people's pain levels fluctuated greatly with their belief that they either were or were not receiving a powerful painkiller, remifentanil -- even though the dose of the drug did not change throughout the experiment.
Pain levels shot up, in fact, soon after participants were told that the drug had been discontinued, something experts call the "nocebo" effect.
The findings suggest that doctors may need to deal with their patients' beliefs about a treatment, whether positive or negative, experts say.
"Our study provides evidence that the expectation of a drug's effect critically influences its therapeutic efficacy," said lead researcher Dr. Ulrike Bingel, from the department of neurology at the University of Hamburg Medical Center in Germany.
"We found that positive treatment expectancy substantially enhanced -- doubled -- the analgesic benefit of remifentanil. In contrast, negative treatment expectancy completely abolished remifentanil's painkilling effect," she said.
"Intriguingly, this very same pattern was found in the activation of those brain areas that are well known to be involved in the intensity of pain," Bingel added.
The study, which also involved researchers from Oxford University in the U.K., is published in the Feb. 16 issue of Science Translational Medicine.
For the study, Bingel's team gave 22 healthy volunteers the opioid painkiller remifentanil and then tested its effect by changing the patient's expectations of the treatment.
The participants were first placed inside an MRI brain scanner, and an intravenous line used to administer the drug was attached. The researchers then applied heat t
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