Optical illusion reduces arthritic pain

An optical illusion can halve the pain of arthritis, a study has found.

Researchers made the discovery by accident during an open day at Nottingham University.

Members of the public were invited to try out some body distortion illusions used in every day research at the university. This involved placing a hand into a box with a camera in it and watching a real-time video of their hand on a screen in front of them.

The technology, known as Mirage, allows the image to be altered to look as if the hand is stretching or shrinking.

Dr Catherine Preston, who collaborated on the study and is now at Nottingham Trent University, said: “During the course of the day the grandmother of one of the children wanted to have a go, but warned us to be gentle because of the arthritis in her fingers.

"We were giving her a practical demonstration of illusory finger stretching when she announced: “My finger doesn’t hurt any more!” and asked whether she could take the machine home with her! We were just stunned — I don’t know who was more surprised, her or us!”

The psychologists recruited 20 volunteers, aged around 70 from a local osteoarthritis group. All were diagnosed with arthritic pain in the hands and/or fingers, and none used anything stronger than paracetamol to manage their pain.

Before testing the Mirage technology, all the volunteers were asked to rank their pain on a 21 point scale, with 0 indicating no pain and 20 representing the most unbearable pain imaginable.

By gently pulling and pushing the hand inside the box, the researchers were able to trick the brain into believing the painful part of the body was being stretched or shrunk.

The technology reduced the pain by half in 85 per cent of the arthritis sufferers.

Some reported greater reduction in pain for stretching, some for shrinking and some for both. The pain reduction only worked when painful parts of the hand were manipulated.

Stretching or shrinking the painful part of the hand temporarily eliminated pain in one-third of all volunteers. Many also reported an increased range of movement, the researchers said.

The study findings are reported in a letter to the journal Rheumatology.

The researchers hope the findings could be the first step towards new technologies for arthritis patients undergoing physiotherapy, allowing health professionals to reduce the pain for sufferers while exercising their joints.

This article was published on Fri 15 April 2011