As debilitating as osteoarthritis can be, it at least develops gradually. That may not seem like much consolation until you consider the other arthritis--rheumatoid arthritis--which in severe cases can hit as fast and hard as a freight train. "People who are jogging one day," says Dr. Stanley Cohen of Dallas' St. Paul Medical Center, "can't get out of bed two weeks later."
Although their symptoms can be similar, the two diseases are very different. Unlike osteoarthritis, which is focused on a particular joint, rheumatoid arthritis is a systemic disease--an autoimmune disorder in which the body's defense system attacks the joints by way of the thin layer of cells called the synovium that line and lubricate the joints. The runaway immune response clogs the synovium with infection-fighting cells that release proteins called cytokines. These are compounds that fuel inflammation. The synovium becomes engorged with new blood vessels and begins to grow, kudzu-like, penetrating and further damaging cartilage and bone.
The most visible symptoms of rheumatoid arthritis are swollen joints and crippling stiffness, particularly of the hands and feet. But it can also cause fatigue, fever and loss of appetite, and in some cases it can affect the heart, lungs and membranes that surround these organs. The disease, which afflicts 2.5 million in the U.S., usually hits people between ages 30 and 50, but it can strike at any age, including childhood. It is three times as common in women as in men and can shorten life by a decade.
When rheumatoid arthritis was given its name in the 19th century, those who suffered from it--including Impressionist master Pierre-Auguste Renoir--had little to look forward to beyond life in a wheelchair. Even in the 1950s, says Cohen, there were still few treatments available. It was treated with aspirin and cortisone, a powerful anti-inflammatory with severe side effects (at lower doses it is still used). Injections of gold salts also provided some relief, although no one really knew why.
Prospects have improved dramatically--especially, says Cohen, "if we treat early and we treat aggressively." Today the most effective treatments for rheumatoid arthritis are combination therapies. Methotrexate, a cancer drug which has been used to treat RA for 30 years, is augmented by other drugs, including the recently developed but costly "biologics" such as etanercept (Enbrel), infliximab (Remicade) and anakinra (Kineret). These are genetically engineered versions of naturally occurring molecules that bind or block the activity of cytokines. Also in very early development are drugs designed to reduce the formation of the blood vessels that feed the tumor-like growth of the synovium.
Researchers are also trying to understand better who gets rheumatoid arthritis and why. They have discovered a genetic marker that is often associated with the earliest onset and most severe forms of the disease. Yet not all rheumatoid arthritis sufferers have the marker (and vice versa), which makes scientists wonder whether rheumatoid arthritis is really a single disease. Environmental factors may also play a role, although no one knows whether the trigger is a virus, bacteria or something else.