If You Think You'll Feel Better, You Will

Study links placebo effect to brain's painkillers

WEDNESDAY, Aug. 24, 2005 (HealthDayNews) -- Pain relief may just be mind over matter.

According to new research, the belief that a pill will relieve pain is enough to cause the brain to release its own natural painkillers.

The finding is the first direct evidence that the brain's own pain-fighting chemicals, endorphins, have a role in the phenomenon known as the "placebo effect" -- and that this response corresponds with a reduction in feelings of pain.

"This is telling us that placebos are powerful," said study lead author Dr. Jon-Kar Zubieta, an associate professor of psychiatry and radiology at the University of Michigan. "When there is a belief that something may take place, this belief actually activates systems in your brain that are directly modifying experience. If you receive a drug and you believe it is active, the drug itself might not be doing very much."

The report appears in the Aug. 24 issue of the Journal of Neuroscience.

"We looked at the response of pain control systems in the brain," Zubieta said. "We observed that a placebo that was believed to be an agonistic agent was able to enhance the release of these anti-pain endogenous opioids."

For the study, Zubieta's team induced pain by injecting concentrated salt water solution into the jaws of 14 healthy young men who agreed to the experiment. The injections were given while the men underwent positron emission tomography (PET) scans.

During one scan, the men were told they would receive pain medicine. Instead, they were given a placebo. Then every 15 seconds during the subsequent scans, the men were 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 telling the men that the placebo was coming, the amount of concentrated salt water needed to maintain the pain increased. This indicated that sensitivity to pain was reduced. So thinking they were getting a pain drug actually allowed the participants to tolerate more pain, the researchers said.

Zubieta classified nine of the men as "high placebo responders" because they exhibited a strong placebo effect. The other five were classified as "low placebo responders."

In addition, the researchers were able to show the power of the placebo effect. "There was more relief in response to this inactive medication as a function of belief," Zubieta said. "In fact, in some areas of the brain, the release was related to how much they believed the drug was going to be effective."

Zubieta believes these findings tell you something about how humans function. "Understanding these mind-body connections are important," he said. "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 said. "You want to enhance the placebo effect under some circumstances," he said. "And in some others you want to reduce it --like when you do a clinical trial."

One expert thinks the findings are important, but miss the larger point.

"It's clearly another step in elucidating these mechanisms, which is really terrific," said Daniel E. Moerman, the William E. Stirton Professor of Anthropology at the University of Michigan in Dearborn, and the author of Meaning, Medicine and the Placebo Effect.

But he added, the question of a mind-body connection as a separation between the two "is not even 16th-century quality thinking," Moerman said. "Socrates did better than that."

"It's only the technology that has made this an interesting area to study," Moerman added. "You can scan this stuff now. You can see it, so there it is, and therefore it's sort of real."

More information

Creighton University can tell you more about the placebo effect.

SOURCES: Jon-Kar Zubieta, M.D., Ph.D., associate professor of psychiatry and radiology, University Michigan Medical School, Ann Arbor; Daniel E. Moerman, Ph.D., the William E. Stirton Professor of Anthropology, University of Michigan, Dearborn, and author, Meaning, Medicine and the Placebo Effect; Aug. 24, 2005, Journal of Neuroscience
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