Seeing the movements of a healthy hand mirroring one's own movements plays a welcome trick on the brains of arthritis sufferers, a new study shows: It reduces the perception of pain. The observation, reported this week at the Society for Neuroscience's annual conference, could offer a safe, inexpensive means of dampening chronic pain by enlisting the brain's power of suggestion.
The small arthritis study, which tested just eight subjects, comes from the lab of UC San Diego neuroscientist V.S. Ramachandran -- who first used mirror-based trickery to treat phantom-limb pain in patients who have had an amputation. In those studies, pain perceived to come from an absent limb resolved when subjects saw what appeared to be their own missing limb moving smoothly and performing tasks without pain.
In the study presented by UCSD neuroscientist Laura Case this week in Washington, eight subjects suffering from severe osteo- or rheumatoid arthritis sat in front of a mirrored box and extended one of their hands. A researcher extended his hand over the subject's hand and asked the subject to move her hand slowly. The researcher, meanwhile, mimicked the subject's hand movement.
The subject, seeing only the researcher's hand in the mirror, saw a young, healthy hand performing movements fluidly and without pain or difficulty. And when asked about their hands' level of pain after the exercise, subjects rated their pain, on average, 1.5 points lower, on a scale of 1 to 10, than it had been at the outset. Some had a 3-point reduction in pain, said Case.