While juvenile arthritis is considered a rare disorder, incidence rates are rising, prompting researchers to wonder why. A new study may have uncovered a link between the soaring rates of obesity and an increase in rheumatoid arthritis, which can develop as early as childhood.
For the study, researchers from the Mayo Clinic examined the medical records of 813 adults with rheumatoid arthritis from the Rochester Epidemiology Project for the years 1980-2007. Then they matched them by age, gender and calendar year to 813 healthy adults as the control group.
The height, weight and smoking status of the study participants were also noted. About 30 percent of the patients in each group were obese and 68 percent were women.
The researchers found that the incidence of rheumatoid arthritis rose by 9.2 per 100,000 women from 1985-2007 and obesity accounted for 52 percent of the increase.
While smoking is known to be a significant risk factor for developing rheumatoid arthritis, the rate of smokers remained constant over the years studied. Therefore smoking was ruled out as a factor in the rise in rheumatoid arthritis.
Fat Cells and Inflammation
While the researchers don’t know exactly how obesity triggers rheumatoid arthritis, they do think the link has to do with the activity of the fat cells themselves.
Unlike osteoarthritis, a form of arthritis that is caused by wear and tear on the joints, rheumatoid arthritis is an autoimmune disease that occurs when the body's immune system attacks the lining around joints. The resulting inflammation leads to the destruction of bone and cartilage. The researchers believe it's the fat cells that spur the inflammation. In the past, other research has found that fat cells are important mediators of inflammation. They are immunologically active and produce proteins that are inflammatory.
Along with many other molecules that increase inflammation, fat cells produce the female hormone estrogen. And given that autoimmune disorders are more prevalent in women, it’s no surprise that three out of four people who have rheumatoid arthritis are women.
While the link between estrogen and rheumatoid arthritis is less clear, the obesity connection is overwhelming. In addition to the current study, past experience treating obese patients tells us that drugs used to treat rheumatoid arthritis generally don't work very well in obese patients.
Is Losing Weight the Answer?
If being obese increases your risk of rheumatoid arthritis, does losing weight help? The researchers say yes. Not only does it help relieve stress on painful and inflamed joints, losing weight usually makes the drugs work better.
About Juvenile Arthritis
Juvenile arthritis affects 300,000 children in the U.S. While there are many forms of juvenile arthritis, one common thread among them is that they can have a serious, even life-threatening impact on a young child.
As July is Juvenile Arthritis Awareness Month, we are joining the Arthritis Foundation in their campaign to help parents recognize signs of the disease and locate resources available for families affected by it.
If your child experiences joint pain, swelling or stiffness in one or more joints for a period of six weeks or longer, seek medical attention as early diagnosis and medical treatment is necessary to prevent permanent joint damage.
Thankfully, advances in research have produced new treatments that moderate the effects of juvenile arthritis and can enable a child with the disease to live an active, full childhood. For additional information and resources, contact the Arthritis Foundation.
Arthritis Care and Research