The Associated Press reports the results of a study, performed by Hamburg's University Medical Center and Oxford University, that connects negative thoughts to an increase in pain sensation.
In the study, researchers attached heat-generating devices onto the legs of volunteer participants. They zapped participants' legs to a pain sensation as high as 70 on a scale of 100. Then they hooked participants up to an IV of a powerful painkiller.
The painkiller they used is a variety that metabolizes quickly, enabling the researchers to change the variables in the study fairly rapidly. They could turn the painkiller on and off, give the participants the medicine or plain liquid.
The researchers misled the participants several times to observe the impact of expectations on pain relief. In one instance, they told the particpants that they were injecting pain killer and that the volunteers could expect relief. They had never turned the pain reliever off, but patients sensed greater relief, up to double the painkilling effect.
In another test, the researchers told participants that they were turning the painkiller off, even though they actually kept the medicine flowing. Despite the actual presence of the pain medicine, volunteers' expectations of renewed pain placed their perception of pain almost at pre-treatment levels.
The Science Translational Medicine journal reported that expections of more pain fired up sections of the brain that control mood and anxiety. Brain scans confirmed that the study participants really did experience the pain sensations that they reported. The "nocebo effect" had as much negative impact on them as the "placebo effect" had positive impact.
In Lauran Neergaard's AP article it's reported that "Spine surgeon Anders Cohen puts a lot of stock in patients' expectations. He prefers to operate only on those who "grab you by the collar and say, 'I can't take it anymore.'" The study appears to confirm that "pessimism can override the effectiveness of treatments."