The causes of Rheumatoid Arthritis are unclear. It is believed that a blend of abnormal autoimmune response, genetic susceptibility and some environmental factors including viruses trigger onset of the disease.
Rheumatoid arthritis is considered an autoimmune disorder. Normally, our immune system makes antibodies that attack bacteria and viruses and protect the body from infections. In Rheumatoid Arthritis, the immune system starts producing antibodies against the body's own cells and tissues which cause the release of chemicals eventually leading to destruction of joint.
About 40% of Rheumatoid Arthritis risk comes from an inherited tendency. Certain genes have been implicated as causes of Rheumatoid Arthritis, like those linked to a certain protein called Human Leukocyte Antigen.
It has been suggested that Rheumatoid Arthritis may occur as response to an infectious agent in a genetically susceptible host. A number of possible causes of Rheumatoid Arthritis have been suggested, including Mycoplasma, Epstein-Barr virus (EBV), Cytomegalovirus, Parvovirus, and Rubella virus. But convincing evidence that these or other infectious agents cause Rheumatoid Arthritis has not emerged.
Habits like smoking induce the release of certain chemicals which may be part of the process triggering Rheumatoid Arthritis. Emotional stress, too, is emerging as one of the leading causes of Rheumatoid Arthritis, especially predisposing to acute episodes of the disease.