New Evidence Shows that Placebo Activates Endorphins to Soothe Pain; Debunks Theory that ‘It’s All in Your Head’
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NEW EVIDENCE SHOWS THAT PLACEBO ACTIVATES ENDORPHINS TO SOOTHE PAIN; DEBUNKS THEORY THAT ‘IT’S ALL IN YOUR HEAD’
WASHINGTON, DC, August 19, 2005 – For the first time, scientists have found that a placebo with implied pain-relieving properties directly activates the brain's chemistry involved in regulating and suppressing pain.
“These findings suggest that improvements in cognitive therapies for pain relief may be a fruitful line of research, in addition to the search for better pain-relieving drugs,” says William Willis, MD, PhD, of the University of Texas Medical Branch at Galveston.
Considerable evidence indicates that the endogenous opioid, or endorphin, system plays a role in placebo effects—the therapeutic benefits obtained after the introduction of an inert substance—that are suggested to reduce pain. Implied pain-relieving placebos have also been associated with reductions in subjects' ratings of their own pain. The release of endorphins is the body's natural way of killing pain.
“The findings of this study are counter to the common thought that the placebo effect is purely ‘psychological,' due to suggestion, and that it does not represent a real physical change,” notes principal study author Jon-Kar Zubieta, MD, PhD, of the University of Michigan. The study appears in the August 24 issue of The Journal of Neuroscience.
Zubieta and his team of scientists have demonstrated that cognitive expectations (i.e., the anticipation of decreased pain) are capable of modulating brain chemical transmission between neurons that are associated with pain reduction. Furthermore, this chemical transmission, occurring at the site of the mu-opioid receptors in the endogenous opioid system, correlated with subjects' report of decreased pain experiences, such as the pain's intensity and unpleasantness.
Researchers used PET and molecular imaging techniques to quantify the activity of endogenous opioids, or endorphins, which are involved in the processes of pain regulation. Scientists intravenously administered a placebo of salt solution, which was presented as a pain-reliever, to 7 healthy male volunteers while they were experiencing moderate, sustained levels of pain. The other 7 volunteers did not receive a placebo while experiencing pain.
PET and molecular imaging techniques revealed that the brains of the volunteers receiving placebos released endogenous opioids. Volunteers also completed several assessments of pain and stress, confirming that they felt less pain. The endorphin activation correlated with decreased elements of the pain experience, depending on the location and magnitude of the endorphins released in the brain.
Zubieta is a member of The Society for Neuroscience, an organization of more than 36,000 basic scientists and clinicians who study the brain and nervous system. The Society publishes The Journal of Neuroscience. Zubieta can be contacted at: zubieta@umich.edu.
