Study participants who take an inert substance (sugar pill, distilled water, saline solution), believing it to be a medication, and benefit, have experienced what researchers call the "placebo effect". The more you believe you're going to benefit, the better the chances are that you will actually see a tangible benefit.
A new study finds that the opposite might also be the case - your pain level might be influenced by the belief that you're being given more (or less) of a powerful medication, even when the dosage hasn't changed.
For the research, the researchers gave 22 volunteers in good health an opioid painkiller and then tested the effect of the drug by changing the patient's beliefs in the outcome of the treatment. Subjects were placed in MRI scanners, an IV started and then heat applied to their leg, causing pain. The heat was set at a level that had the subjects rating pain levels at around 70 out of a possible 100. At this time the volunteers were given the painkilling drug, but told nothing.
At this point, pain levels dropped from 66 to 55 on that 100 rating system. The researchers then informed the subjects that the drug had just been started (even though they'd already been receiving the drug) and as you would expect, pain levels fell off quite a bit, to just 39 points. Interesting that pain levels for subjects went up when they were informed that the pain medication had been discontinued (the "nocebo" effect).
To learn more about the nocebo effect, neurologists then told the subjects they were ceasing to administer the medication, and that they might begin to experience higher levels of pain, even though the drug was still being administered. At this point in the experiment, the subject's pain levels rose to an average score of 64 out of 100. So the pain was right back up at the place it was before any medication had been given.
MRI scans at each point of the experiment showed differing levels of brain activity depending on the subject's expectation of pain or relief of pain. In those who were informed they were receiving the painkilling medication, sections of the brain that were engaged made it harder for pain signals to reach the brain or spinal cord.
This suggests that a physician may need to be aware of a patient's beliefs about a medication - both positive and negative - according to the researchers. It appears from this work that the expectations of a drug's affect influences its therapeutic effectiveness. So having positive expectancy doubled the analgesic effects of the medication being used. While negative expectancy completely abolished the painkilling effect.
Intriguing that this pattern was discovered in the triggering of brain areas identified as being involved in the sensation of pain intensity.
The work does open up a new area of research - linking drugs and patient personalities and expectations. The findings on the reverse placebo effect also have impacts on clinical practice - patients' beliefs, expectations and earlier experiences with treatments should be assessed and integrated into the treatment plan for any condition.
