Sunday, March 11, 2007

Your brain ... ... on pain ... and on placebo

Two weeks into a clinical trial for a pain-relief therapy, volunteer patients noted remarkable results -- both good and bad.

All 270 participants with a history of arm discomfort reported a decrease in pain. Half also complained of common side effects, such as dry mouth and drowsiness.

The findings astounded Ted Kaptchuk, a Harvard Medical School professor and the study's designer, because none of the volunteers received "real" medicine, only a placebo or sham acupunc ture treatment. The point of the study was to gauge the "placebo ef fect," the notion that patients often respond to the illusion of treatment for conditions as varied as pain, asthma, depression and hyperten sion.

Kaptchuk's study published last year is part of a growing body of research that suggests the placebo effect is more unwieldy and problematic than medical researchers previously understood.

For the pharmaceutical indus try, greater insight into the placebo effect has enormous implications because of the central role of placebos in randomized, double- blind clinical trials -- the gold standard for testing the efficacy and safety of medicines in the United States and Canada.

"The placebo effect is distressing the drug companies because they know they have pharmacological agents that are good and too many unsuccessful clinical trials," Kaptchuk said. "There is definitely some sort of crisis that nobody is acknowledging."

While the causes of the placebo effect remain a mystery -- buried near the intersection of psychology and physiology, mind and body -- no one doubts that it is real. In clinical trials, an average 35 percent of volunteers given a placebo respond the same way as volunteers given a real medicine or other therapy.

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