Lithium, a drug widely used to treat mental illness, may have potential to treat arthritis, a new study shows.

Osteoarthritis is a very common ailment of aging. It results from joint inflammation that over time leads to degradation of cartilage tissue, causing pain and immobility.

Although there are treatments to relieve pain, nothing has been found that stops the arthritis disease process.

Researchers in the UK and New Zealand tested the effect of lithium chloride, a mineral salt used to treat people with manic depression.

They used animal cartilage samples exposed to inflammatory molecules to mimic the effects of arthritis and then treated the tissue with lithium chloride.

The study showed that the commonly used drug prevented the degradation and loss of mechanical integrity of cartilage in arthritic joints.

Could lithium be the long-sought cure for osteoarthritis, which affects some 27 million Americans?

"While we're still at an early stage in researching lithium's effects on cartilage and its suitability as a treatment, the possibility that an already widely available pharmaceutical could slow the progress of osteoarthritis is a significant step forward,” said Professor Martin Knight, co-author of the study, which is published in the Journal for Orthopaedic Research.