Johns Hopkins Health Alerts | Arthritis | Causes of Rheumatoid Arthritis

Several factors may increase your risk of developing rheumatoid arthritis, but for now the true cause of rheumatoid arthritis remains a mystery.

Rheumatoid arthritis affects approximately 2.1 million Americans. Unlike osteoarthritis, which occurs equally in both sexes, more than three times as many women as men have rheumatoid arthritis. Osteoarthritis usually begins late in life; rheumatoid arthritis often begins between ages 30 and 50, though it can develop at any age.

The major distinguishing characteristic of rheumatoid arthritis is that it is a chronic, systemic (affecting the whole body), inflammatory autoimmune disease. What does this mean? In an autoimmune disease, something triggers the body to mount an immune system attack against itself, much the way the immune system normally attacks harmful bacteria and viruses. In rheumatoid arthritis, the primary target of this attack is the synovial membrane that lines joints in every part of the body.

The exact cause of rheumatoid arthritis is still unknown, but researchers have identified some factors that may increase your risk of developing the disease.

• The Role of Genetics and Rheumatoid Arthritis
  Rheumatoid arthritis can run in a family. But even if you have rheumatoid arthritis, your children’s risk of developing it is not greatly increased. Researchers have identified a specific genetic marker called HLA-DR4, which is found in more than two thirds of white men and women who have rheumatoid arthritis. However, about 20% of people without rheumatoid arthritis have the same genetic marker. So having the marker increases your risk of rheumatoid arthritis but does not mean that you’ll inevitably develop the disease.
• The Role of Infection and Rheumatoid Arthritis.
  Several types of arthritis occur as a result of infections. You’re probably familiar with Lyme disease, which is the result of a bite from an infected deer tick. The bacterium the tick transmits first causes a rash, fever, and neck stiffness. Weeks later, victims may develop severe joint inflammation (Lyme arthritis) that can last for months, or even for a lifetime. Some researchers think that in people who are genetically susceptible to rheumatoid arthritis, exposure to certain bacteria or viruses can trigger the abnormal immune response that causes the disease.
• Environmental Factors and Rheumatoid Arthritis.
  Several studies have found that heavy smokers are more likely to develop rheumatoid arthritis than nonsmokers. Other studies suggest that drinking coffee might also increase the risk of rheumatoid arthritis and that drinking tea might decrease the risk. However, a 2003 review of data from more than 80,000 women studied for nearly 20 years concluded that neither beverage affects rheumatoid arthritis risk.

Johns Hopkins Health Alerts | Arthritis | Causes of Rheumatoid Arthritis