The study is the first to pinpoint a specific brain chemistry mechanism for a pain-related placebo effect. It may help explain why so many people say they get relief from therapies and remedies with no actual physical benefit.
“This deals another serious blow to the idea that the placebo effect is a purely psychological, not physical, phenomenon,” says lead author Jon-Kar Zubieta, M.D., Ph.D., associate professor of psychiatry and radiology at the U-M Medical School. “We were able to see that the endorphin system was activated in pain-related areas of the brain, and that activity increased when someone was told they were receiving a medicine to ease their pain. They then reported feeling less pain. The mind-body connection is quite clear.”
The findings are based on sophisticated brain scans from 14 young healthy men who agreed to allow researchers to inject their jaw muscles with a concentrated salt water solution to cause pain. The injection was made while they were having their brains scanned by a PET scanner. During one scan, they were told they would receive a medicine (in fact, a placebo) that might relieve pain.
The persons were asked to rate the intensity of their pain sensations. The scientists correlated the participants’ ratings with their PET scan images. As the researchers alerted participants that the placebo was coming, and injected the placebo dose, the amount of additional concentrated salt water needed to maintain participants’ pain over time increased - indicating a reduction in pain sensitivity that the subjects were not aware of.
All of the participants showed an increase in the activation of their mu-opioid endorphin system after they were told that the “medicine” was coming and the placebo was given. The most pronounced differences were seen in four areas of the brain known to be involved in complex responses to, and processing of, pain: the left dorsolateral prefrontal cortex, the pregenual rostral right anterior cingulate, the right anterior insular cortex and the left nucleus accumbens.
MEDICA.de; Source: University of Michigan Health System