Acupuncture: beyond the placebo effect

Researchers at the University of Southampton and University College London have shown for the first time that the impact of acupuncture goes beyond the acknowledged placebo effect caused by the patient's own expectation of feeling benefit from the treatment.

The scientists from Southampton, Dr George Lewith and Dr Peter White of the University's Complementary Medicine Research Unit, have distinguished between the placebo effects produced by a patient's expectation and the real effects of treatment in a group of patients with painful osteo-arthritis, by monitoring specific responses in the brain during treatment.

Working with the Functional Imaging Unit at University College London, Dr Peter White of Southampton and Dr Jérémie Pariente of UCL used sophisticated Positron Emission Tomography (PET) scans to find out what happened in the brains of patients receiving acupuncture-related treatment.

In one intervention patients were touched with blunt needles but were aware that the needle would not pierce the skin and that it did not have any therapeutic value. Scans showed that only the areas associated with the sensation of touch were activated in their brains.

Another intervention involved being treated using specially developed needles that give the impression of skin penetration without actually piercing the skin. The needles work like stage daggers, with the tip disappearing into the body of the needle when pressure is applied. These patients believed that the treatment was real and scans showed an area of the brain associated with the production of natural opiates - substances that act in a non-specific way to relieve pain - was activated in these patients.

Finally, the third intervention was real acupuncture. As well as the opiate centre, another region of the brain, the ipsilateral insular, was also activated during the treatment. This is a pathway known to be associated with acupuncture treatment and thought to be involved in pain modulation.

The brain activity in the third group of patients shows that real acupuncture elicits a demonstrable physiological effect over and above a simple skin prick. In addition, the response of the second group of patients who received the sham acupuncture treatment, indicates that the expectation of and belief in the treatment also has a physiological effect on the brain. The expectation appears to mediate a potentially powerful although non-specific clinical response to acupuncture.

Dr George Lewith comments: "By indicating a very specific neuronal pathway for acupuncture treatment, this research is an important step forward for understanding the basic mechanisms involved in acupuncture and placebo."

The findings are published in the 1 May edition of the journal NeuroImage. Dr Lewith and Dr White hope to continue their work with a more detailed programme of research, in conjunction with their colleagues.