Natural magnets, believed by many to ease pain, may actually do little to that effect, new research reports.

A U.S. investigator found that magnets did not appear to affect the nerve fibers that transmit information about touch to the spinal cord, which tend to be much more sensitive to stimulation than the nerves that transmit pain signals.

So if these highly sensitive touch nerves aren't affected by magnets, "it would be a miracle" if magnets could influence the less sensitive pain nerves, Dr. David W. Garrison stated.

These results, which appear in the American Journal of Pain Management, suggest that it would be "seemingly farfetched that (magnets) are doing something to alleviate pain," he said.

In an interview, Garrison noted that many people believe that magnetic fields -- which clearly affect bird migration, for example -- could also have effects on the human body. Some argue that magnets might ease pain by increasing blood flow or blocking nerve impulses that carry pain information, he said.

To test whether these theories are correct, Garrison asked 49 healthy volunteers to wear either a magnet or a dummy magnet over the median nerve, leading to their wrist. The researcher, based at the University of Oklahoma Health Sciences Center in Oklahoma City, then tested participants' perception of touch.

During one experiment, Garrison touched their fingers with two different points very close together, slowly moving them apart, and asked the subjects to tell him when they could feel two distinct points. The researcher also touched participants very lightly with one point, and participants told him when they could feel the point for the first time.

This information is transmitted by nerve fibers associated with touch, Garrison explained, which are much more sensitive than nerves that convey pain information. When people wore magnets, they didn't perceive the two points or the single point any sooner or later, suggesting that the magnets did not influence the touch nerve cells, he said.

Magnets "didn't change the physiology of the neurons that bring the information in," he said.

And if magnets did not affect touch nerve cells, they likely could not affect nerve cells associated with pain, he concluded.

However, these findings do not necessarily mean that people get no relief from their pain by wearing magnets, Garrison added. Many magnet-wearers may simply benefit from the placebo effect, in which people who are given an inactive drug or therapy experience an improvement in their symptoms.

In addition, Garrison said that magnets may ease pain through so-called "gating."

When people feel pain in their wrists from carpal tunnel syndrome, the researcher explained, nerve cells are sending that pain information to the spinal cord. However, if people wear a bracelet that contains a magnet to ease the pain, the pressure from the bracelet will activate other nerves that transmit information about touch to the spinal cord, and these nerves will start to compete with the pain nerve signals, limiting the amount of pain information reaching the brain.

This theory also helps explain why rubbing a painful spot can often make it feel better, Garrison added.

SOURCE: American Journal of Pain Management, July 2004.

Reference Source 89
Aug 25, 2004

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