A brain imaging study, conducted by researchers at the University of Michigan, has revealed that our bodies' natural painkilling system might play a role in the placebo effect.
The researchers injected saline solution into the jaws of 14 healthy male volunteers. The procedure is harmless, but slightly painful, so all were told to expect painkilling medication. Some of the subjects were given real painkillers, others were given placebos.
All groups recorded their experience of pain every 15 seconds over the course of the 20 minute procedure, while their brains were scanned with the PET (positron emission tomography) machine.
When subjects were told they would receive painkillers, the parts of the brain that produce our bodies' natural painkillers, the mu-opioid receptors, kicked up a storm.
The brain activity was proportional to the expectations the subjects had about how effective the painkillers would be. The researchers say this is the first direct evidence that endorphins can help explain how the placebo effect works.
"This deals a serious blow to the idea that the placebo effect is a purely psychological, not physical, phenomenon," lead researcher Jon-Kar Zubieta told SciAm. "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."
The research was published in the Journal of Neuroscience.
Suitably inspired, The Register's technical gurus are currently working on a picture of a giant aspirin that will work (placebo-like) to rid our gentle readers of any eyestrain so they can keep looking at our lovely adverts (hint, hint) as well as reading the stories. ®
Explanatory note: The placebo effect is defined very nicely (here), as "a beneficial effect in a patient following a particular treatment that arises from the patient's expectations concerning the treatment rather than from the treatment itself".
It follows, then, that a placebo is a non-active 'medication' that a patient believes to be a drug of some kind.