Placebo: the real deal

SHAM medicines can sometimes bring real pain relief. Now scientists say they know why. New research shows that the “placebo effect” has a real physiological basis: It triggers the brain’s pain-fighting chemicals. The findings could boost the search for drug-free ways to treat pain.

“Just the expectation of pain relief is enough to activate anti-pain mechanisms,” says lead scientist Jon-Kar Zubieta, a neuroscientist at the University of Michigan in Ann Arbor.

Previous research has shown that sham treatments, or placebos, can improve pain, but scientists were unsure how. Zubieta and colleagues show that people alleviate their own pain by releasing natural painkillers in their brains.

Researchers injected saline solution into the jaws of 14 young, healthy men to cause pain. The test subjects were told they would also receive a painkiller, but they were actually given intravenous saline. Scientists then looked at brain scans recorded during the experiment to see how the sham treatment affected the brain.

They found that when people were expecting medication, they showed an increase in endorphins -- natural compounds similar to opiates -- in parts of the brain that process pain. As their endorphins increased, people reported less pain.

“It’s a form of resiliency,” says Zubieta. “You are able to mobilize your own resources to counteract pain.”

He says the research could be used to develop new pain treatments, such as cognitive techniques that are frequently used to help people overcome anxiety and depression. The results were reported in the Aug. 24 issue of the Journal of Neuroscience.