May 1, 2005

Acupuncture activates the brain

Medicinal use of needles does more than placebos.

by Andreas von Bubnoff
Nature News

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Acupuncture has a measurable, if mysterious, effect on the brain, UK scientists have found. The study adds to evidence that patients benefit from acupuncture not simply because of their expectations.

The research team used brain imaging to show that treatment with genuine needles activates brain areas beyond the ones that light up when trick needles are used. "This is the first brain-imaging study that has shown an effect beyond placebo," says George Lewith, an expert in complementary medicine at the University of Southampton who led the study.

Part of this confusion may be thanks to the use of badly defined controls in acupuncture tests, experts say. Some studies use needles in non-acupuncture points, for example. But this may simply prove that needling is an effective treatment.

Stage dagger

For a better placebo, Lewith's team used a retractable needle that doesn't really penetrate the skin, but tricks the patients into thinking that it does. "It disappears into its handle like a stage dagger," Lewith says. This tricked the patients into believing they were being treated when they weren't.

The study group, which consisted of 14 patients with arthritic pain in their thumbs, was also treated with both real acupuncture, and with blunt needles that didn't penetrate the skin. In the last case the patients were told that the procedure should not have any effect.

The researchers then used positron emission tomography to measure brain activity. Both placebo treatment and real treatment activated the brain in areas known to respond to opiates: painkillers released by the brain.

Insula effect

True acupuncture also increased activity in a different brain area called the insula, which is part of the cerebral cortex. It's not clear what this activity means, says Lewith, but it indicates some sort of real effect. "What we have demonstrated is that acupuncture is partially modulated by expectation, but is probably also modulated by a real treatment effect," he says. They report their findings in the journal NeuroImage.

Lewith adds that his own previous work has indicated that expectation accounts for some of acupuncture's benefits. In a study of people with chronic neck pain, they found the placebo effect accounted for about 80% of pain relief.

Kaptchuk says that the study should help researchers to design better clinical trials of acupuncture in the future. "This study gives a clarification of the possible mechanisms by which acupuncture works, and by understanding the mechanisms we can design better placebos," he says.

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