What Causes Rheumatoid Arthritis?

Rheumatoid arthritis (RA) is a chronic autoimmune disease where your immune system attacks healthy tissue in your body, causing inflammation in your joints. In the early stages, people with RA typically experience pain in their hands, knees, and wrists. However, if this condition is left untreated, tissue damage can occur in larger joints like the hips and knees.

While experts know how RA affects the body, it's less clear what causes RA in the first place. However, having certain risk factors can make you more likely to develop the condition.

Risk Factors

Researchers do not currently know what specifically causes RA. The mystery surrounding the cause of RA is consistent with other autoimmune diseases. The National Institute of Arthritis and Musculoskeletal and Skin Diseases explains that there is little information about why autoimmune diseases develop in the first place.

However, researchers do know that a combination of genetic and environmental risk factors can trigger the immune system to attack healthy cells. These factors can explain why some people may be at a higher risk of developing RA. 

Genetics

People born with certain genes, such as the human leukocyte antigen (HLA) genes (the genes responsible for immune system regulation), may be more likely to develop RA.  But, not everyone born with these genes will automatically develop the condition. In most cases, your risk of developing RA is higher if your genes are also combined with environmental risk factors, like obesity, stress, or smoking. 

Some experts also believe that RA can run in families. You may have a slightly higher risk of developing RA if your family members also have this condition compared to those who don’t have a family history of RA.

Sex

People who are assigned female at birth are two to three times more likely to have RA than those assigned male at birth. While research on this risk factor is still being studied, researchers have a theory that the hormone estrogen may play a role in the development of RA. 

According to a study in Rheumatology, having had at least one pregnancy, being newly postpartum, practicing long-term breastfeeding, and going through early menopause can all increase your risk for RA. The study suggests that the fluctuating hormone levels throughout a woman's life and the inflammatory effects of estrogen may affect your immune response.

Age

Unlike other types of arthritis, RA can develop at any age. However, your risk of getting RA increases as you age. One study found that more than 50% of people with RA are 65 years or older at the time of their diagnosis.

Smoking

A history of smoking can greatly contribute to the onset of RA. Research published in the International Journal of Molecular Sciences suggests that the stress and inflammation smoking causes can make you more susceptible to developing RA and can affect your treatment outcomes.

The study also investigated the relationship between smoking and assigned sex at birth. According to their findings, men who smoke were twice as likely to develop RA than non-smokers, and women who smoke were 1.3 times more likely to have RA than non-smokers. 

The connection between smoking and RA extends beyond just those who smoke. Secondhand smoke, or smoke that you can inhale from someone else’s smoked cigarettes, can also increase the risk of RA. One study found that adult women who were exposed to cigarette smoke as a child were more likely to develop RA than adult women without smoke exposure during childhood.

Obesity

Experts are still studying how big of a role obesity plays in raising your risk for RA.  But, there is a correlation between obesity and RA: as the obesity epidemic continues to grow, there are more cases of RA.  

The number of RA cases has steadily grown since the 1990s. A 2014 study in Arthritis Care & Research suggests that obesity might be responsible for more than half of the recent increase in RA cases among people assigned female at birth.

One of the main connections between obesity and RA may be cytokines or inflammatory proteins in your tissue. Research shows that higher levels of body fat can raise your cytokine levels and increase the risk of inflammation in your joints.

Stress and Illness

Your body's response to viral or bacterial infections, injury, and stressful life events (e.g., job loss or divorce) may lead to an overactive immune system response. This can increase your risk of developing RA. 

When you are under physical or emotional stress, your body can release a chemical reaction that makes your heart beat faster, adds tension to your muscles, and increases inflammation in your immune system. The longer you are exposed to stress, the more inflamed your immune system and joints can become.

A Quick Review

RA is a chronic autoimmune condition that causes pain and inflammation in your joints. The cause of RA is still unknown, but researchers suspect that a variety of risk factors can increase your risk of developing the condition. These risk factors can include genetics, obesity, and long-term tobacco use. 

Living with RA can be painful. If you think you are experiencing RA symptoms or may be at risk for developing RA, reach out to your healthcare provider about the next steps. Through a physical exam and a variety of blood or imaging tests, they can determine the cause of your symptoms and give you an official diagnosis.