As would be expected with the powerful drug taking effect, the average level of self-reported pain participants felt declined a bit, falling from 66 points down to 55 on a 100-point scale.
The researchers then told the volunteers that the remifentanil was starting (even though they had already been getting the drug). The result: participants' average pain levels fell dramatically, to 39 points.
To test the "nocebo" effect, Bingel's team then told the volunteers they were stopping the drug and they might start to feel more pain again -- a lie, since they continued to administer the same level of the painkiller.
At this point, the volunteers' self-reported pain levels shot back up to an average of 64 points -- that is, the pain was as great as if they had received no pain relief at all.
In each stage of the experiment, MRI scans showed different brain activity in responses to the volunteer's varied expectations of pain or pain relief, the researchers said. Specifically, in people who were primed to think they were getting the painkiller, areas of the brain were engaged that made it more difficult for pain signals to reach the brain or spinal cord, the researchers said.
Bingel believes that the data "opens a new avenue of research," linking up drugs with patients' personalities and expectations in the context of specific medical conditions.
The findings also have implications for clinical practice, she said. "We believe that the beliefs, expectations and previous experiences with drug treatments should be more systematically assessed and integrated [by doctors] to optimize the overall treatment outcome."
One expert agreed.
Dr. Fatta B. Nahab, an assistant professor
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