The exact cause of rheumatoid arthritis is unknown. We know how the condition attacks the joints, but it is not yet known what triggers the initial attack. Some theories suggest that an infection or a virus may trigger rheumatoid arthritis, but none of these theories has been proven.
Autoimmune condition
Rheumatoid arthritis is an autoimmune condition. This type of condition causes the body’s immune system to attack itself. Normally, your immune system makes antibodies that attack bacteria and viruses, helping protect your body against infection. If you have rheumatoid arthritis, your immune system sends antibodies to the lining of your joints, where instead of attacking harmful bacteria, they attack the tissue surrounding the joint.
Synovium
The synovium is a membrane (thin layer of cells) that covers each of your joints. When antibodies attack the synovium, they leave it sore and inflamed. This inflammation causes chemicals to be released, causing the synovium to thicken. These chemicals can also damage bones, cartilage (the stretchy connective tissue between bones), tendons (tissue that connects bone to muscle) and ligaments (tissue that connects bone and cartilage). The chemicals gradually cause the joint to lose its shape and alignment and, eventually, can destroy the joint completely.
Genetic susceptibility
There is some evidence that rheumatoid arthritis can run in families. Your genes may be one factor in the cause of the condition. However, having a family member with rheumatoid arthritis does not necessarily mean that you will inherit the condition. Even an identical twin of someone with rheumatoid arthritis only has a one in five chance of developing it, so genes do not explain much of the risk.
Hormones
Rheumatoid arthritis is three times more common in women than in men. This may be due to the effects of oestrogen (a female hormone). Research has suggested that oestrogen may be involved in the development and progression of the condition. However, this has not been conclusively proven.
Want to know more?
- National Rheumatoid Arthritis Society: Why me?
