November 11, 2011
Dear Mayo Clinic:
What causes rheumatoid arthritis to develop?
As with many diseases, the causes of rheumatoid arthritis appear to be a combination of genetic and environmental factors. The genetic factors that affect the development of rheumatoid arthritis cannot be changed. But the environmental factors can. For example, the most critical lifestyle change a person can make to reduce the risk of developing rheumatoid arthritis is not smoking.
Rheumatoid arthritis is a chronic, progressive autoimmune disorder. In these disorders, the immune system mistakenly targets healthy organs and tissue in the body. In people with rheumatoid arthritis, white blood cells — whose usual job is to attack unwanted invaders such as bacteria and viruses — move from the bloodstream into the membranes that line and surround the joints (synovium) and cause inflammation.
Swollen, sore and/or stiff joints are the most common symptoms of rheumatoid arthritis. The disease may also cause firm bumps of tissue, called rheumatoid nodules, to form under the skin of the arms. In some people, rheumatoid arthritis can cause fatigue, weight loss and fever.
The smaller joints, such as the knuckle joints in the fingers and toes, are usually the first to be affected by rheumatoid arthritis. As the disease progresses, symptoms often spread to the knees, ankles, elbows, hips and shoulders. In most cases, symptoms occur in the same joints on both sides of the body. Over time, rheumatoid arthritis symptoms may come and go, with periods that are relatively symptom-free alternating with periods of increased symptoms.
The exact cause of rheumatoid arthritis isn't clear, but researchers believe genetics plays a role. Many people who acquire the disease have a family history of rheumatoid arthritis. Although genetics alone does not appear to cause the disease, genetic makeup seems to make some people more vulnerable to developing rheumatoid arthritis.
Gender and age are also risk factors. The disorder is two to three times more common in women than men. Even though it can affect people of any age, rheumatoid arthritis is also much more common in people older than 40. Most often, the disease begins between the ages of 40 and 60.
While there's no changing genetics, gender or age, smoking is one big risk factor that a person can control. Research has shown that smokers have a much higher risk of developing rheumatoid arthritis than nonsmokers. Once someone has the disease, smoking has also been shown to make symptoms worse, increasing joint stiffness and pain. So if you smoke, quit, and if you don't smoke, don't start.
Recent research also shows there may be some association between rheumatoid arthritis and poor dental health and related conditions — such as a significant gum disease called periodontitis. The possible connection is still under investigation, but it appears that mouth infections may have an impact on a person's immune system, possibly setting the stage for rheumatoid arthritis. While additional study is needed to find out more about poor dental health as a risk factor for rheumatoid arthritis, this is a fascinating new research area in rheumatology.
If you are concerned that you could be at increased risk for rheumatoid arthritis, talk to your doctor. Although some risk factors that can make you vulnerable to this disease can't be changed, there may be ways you can change environmental factors to lower your risk for rheumatoid arthritis.
— Nisha Manek, M.D., Rheumatology, Mayo Clinic, Rochester, Minn.