Causes of Rheumatoid Arthritis

Medically reviewed by Brenda B. Spriggs, MD, FACP on February 16, 2017Written by Rachel Nall, RN, BSN, CCRN

Overview

Rheumatoid arthritis (RA) is an autoimmune disorder that causes inflammation in the joints. RA also causes your body’s immune system to attack your joints. Doctors don’t know what causes this condition. But the following factors could play a role in triggering it:

  • genetics
  • trauma
  • sex
  • infection with a bacteria or virus

The joints most affected by RA are the hands and feet. People with RA experience stiffness in the joints and other symptoms like problems with their lungs, heart, and eyes.

According to the , an estimated 1.3 million Americans have RA. An estimated three-fourths of them are women.

Genetics and RA

A family history of RA can increase your chances for developing the condition. Researchers have also identified genes associated with a greater risk of RA.

One example is the HLA genetic marker. According to the , a person with the HLA marker is five times more likely to have RA than those without it. Having the HLA marker doesn’t mean you ‘ll develop RA. It only means increased risk.

There are also other genes linked with RA. These include:

  • PTPN22: Researchers think this gene plays a role in the development and progression of RA.
  • STAT4: This gene handles activating and regulating the immune system.
  • TRAF1 and C5: Researchers associate these genes with chronic inflammation.

According to the , it’s likely more than one gene determines if a person develops RA. This is would also determine the severity of their condition.

Can you inherit rheumatoid arthritis? »

Infectious agents and RA

Researchers suspect infectious agents like bacteria could cause inflammation that triggers RA. They’ve detected bacteria in the synovial tissue that surrounds the joints.

A study, published in the December 2016 journal from Johns Hopkins University, found bacteria known to cause chronic inflammatory gum infections may trigger RA.

There is a link between having an Aggregatibacter actinomycetemcomitans infection (bacteria associated with periodontal disease) and greater production of proteins known to trigger RA. But this bacterium is not likely the sole cause of RA. Half of the study’s participants didn’t have the bacterium in their mouths.

Viruses may also play a role in triggering RA. According to the , people with RA, on average, have higher levels of antibodies to the Epstein-Barr virus (which causes mononucleosis) than the general population.

The Epstein-Barr virus isn’t the only virus suspected as an infectious agent in RA. Other examples include retroviruses and parvovirus B19, which causes fifth disease.

Trauma and RA

Researchers have linked physical trauma as a potential contributor to the onset of RA. According to a study published in the journal , trauma can trigger inflammation that could lead to developing RA.

Examples of trauma include:

  • bone fractures
  • joint dislocations
  • ligament damage

But the researches did not point to any significant evidence that could connect trauma to the development of RA.

Large-scale, long-term research studies are needed to determine a true cause-and-effect. This is because trauma may not immediately trigger RA. It could cause inflammation that could one day lead to RA.

Smoking and RA

Cigarette smoking can affect the onset of RA, the severity of symptoms, and the effectiveness of treatment. A study published in found that even light smoking links to an elevated risk of RA.

The study also showed smoking daily could more than double a woman’s risk of developing RA. The likelihood of developing RA decreased after quitting smoking. The risk also continued to decrease over time.

The participants’ risk decreased by one-third 15 years after they quit smoking. The risk of RA was still much higher in former smokers 15 years after quitting than for those who never smoked. Researchers think smoking causes faulty immune functioning if you already have certain genetic factors that make you more likely to develop RA.

The effects of smoking on the body »

Smoking can increase the severity of symptoms in people with RA. It can also interfere with the effectiveness of your RA medications or other treatments. And smoking may make it more difficult to exercise.

If you need surgery, smoking may increase the chances of complications. Nonsmokers seem to do better after surgery.

Never smoking or quitting smoking can help reduce your chances of developing RA.

Create a plan to quit smoking today »

Other possible risk factors and causes

Hormones

A larger number of women have RA compared with men. So, female hormone levels may contribute to the disease’s development. For example, some women may have fluctuations of RA symptoms when they are pregnant. A woman’s symptoms may subside when she’s pregnant and then worsen after pregnancy.

Breastfeeding, and the increased hormone levels associated with it, may also worsen RA symptoms. Taking birth control is also associated with an increased risk for developing RA.

Irritants and pollutants

Researchers have linked exposure to air irritants to developing RA. Examples include:

  • cigarette smoke
  • air pollution
  • insecticides
  • exposure to minerals in the air, such as silica and asbestos

Obesity

According to the , an estimated two-thirds of people with RA are obese or overweight. Fat in the body can release proteins that are connected with causing inflammation. Specifically, fat releases cytokines, which are also compounds released in inflamed joints. The more a person is overweight, the more severe their RA symptoms seem to be.

Obesity also seems to affect traditional RA treatments. A class of anti-RA drugs known as disease-modifying antirheumatic drugs (DMARDs), are less effective over the course of a year in people who are overweight compared with people with RA who are average weight. Being obese alone isn’t likely a sole contributing factor to RA.

Takeaway

RA is a disease with some contributing factors like genetics, the environment, and hormones. Other conditions like trauma and infections are important to recognize as potential trigger mechanisms.

There are a few known factors that you can alter to reduce your risk. They include:

  • quitting smoking
  • losing weight
  • limiting your exposure to environmental pollutants, like air pollution and hazardous chemicals
  • seeing your doctor as soon as you develop symptoms, since early and aggressive treatment may delay disease progression

Taking these steps may also keep RA from getting worse. Continuing research to determine potential causes and targeted treatments for managing RA remains a priority for researchers.

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