Pain relief may be mind over matter. According to new research, just the belief that a pill will relieve pain can cause the release of endorphins, the brain's natural pain-fighting chemicals. This finding is the first direct evidence that endorphins play a role in the well known placebo effect.

The Study

Lead author Dr. Jon-Kar Zubieta, an associate professor of psychiatry and radiology at the University of Michigan Medical School, and his team induced pain by injecting a concentrated saltwater solution into the jaws of 14 healthy young male volunteers. The injections were given while the men underwent positron emission tomography (PET) scans of their brains.

During one scan, the men were told they would receive pain medication, but were given a placebo instead. The men were then asked to rate the intensity of their pain on a scale of 0 to 100. After the experiment, they provided more detailed pain ratings.

The researchers found that after giving the men the placebo, the amount of concentrated saltwater needed to maintain the pain increased, indicating that sensitivity to pain was reduced. Thinking they were getting a pain medicine actually allowed the participants to tolerate more pain, the researchers conclude.

"We looked at the response of pain control systems in the brain," Zubieta says. We observed that a placebo that was believed to be a [medication]was able to enhance the release of these antipain opioids. In fact, in some areas of the brain, the release [of endorphins] was related to how much the participants believed the drug was going to be effective," Zubieta adds.

The Power Of Placebo

"When there is a belief that something may take place, this belief actually activates systems in your brain that are directly modifying experience," says Zubieta. "If you receive a drug and you believe it is active, the drug itself might not be doing very much."

Zubieta believes these findings show something about how humans function. "Understanding these mind-body connections are important," he says. "There are many treatments that are believed to be effective, when in reality they may not be more effective than placebo."

Harnessing the placebo effect may have some positive therapeutic applications, Zubieta says. "You want to enhance the placebo effect under some circumstances," he says. 'And in some others, you want to reduce it-like when you do a clinical trial."

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