Although the exact causes of rheumatoid arthritis are unknown, we do know it to be an autoimmune disease. This means that the body's own immune system does not operate normally - but instead attacks healthy joint tissue - starting a process of persistent inflammation that ultimately leads to irreversible joint damage.
Ironically it is the body's reaction to the inflammation, rather that the inflammation itself, that inflicts most of the damage on the body.
Many things are suspected of causing this 'mistaken identity'. The disease may be triggered by a bacterial or viral infection that changes the synovial membrane in some way so that it is recognised as foreign. The reasons why such an inflammatory response should persist to produce rheumatoid arthritis is an area of ongoing research.
To date there is no known single cause; multiple factors are involved, with different causes working in different people.
Risk factors
As with other types of arthritis, age is a strong risk factor. While the condition can develop at any age, it generally affects people in early middle age (between 30-60).
It is more common in women than men at a ratio of 5:2. The reasons for this are unclear.
Genetic factors also have a role but remain unclear. Although rheumatoid arthritis is not directly inherited, there is evidence that certain genes which play a role in the immune system may be involved in determining the susceptibility, development and severity of disease in some people - but they are not definitive. In other words, you can still develop the condition without these genes and equally you can have these genes and never develop it. One of these genetic markers is called HLA-DR4.
Where you live can have an impact - it seems to be more common and severe in Northern Europe. Again, the reasons for this are currently unclear.
Food - the relationship between diet and arthritis in general is the subject of much debate. For more information see the Arthritis topic.
Stress, environment and hormones are all suspected triggers of rheumatoid arthritis.
Smoking has been shown to induce increased complications with the condition.
15/05/2009