Autoimmune diseases are increasingImpact-Photography/Shutterstock
Our immune system helps to fight off infections from viruses and bacteria—but sometimes it can turn on itself by mistake. So what is autoimmune disease, and why do you need to know about it? “Autoimmune disease occurs when the immune system attacks a person’s own cells and tissues,” says Daniela Cihakova, MD, PhD, an immunologist at Johns Hopkins University. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), this can happen in almost any part of the body, from the brain to muscles, skin, and other organs. And the research is clear—the number of people with one of these conditions has been increasing in the last several decades. The National Institutes of Health (NIH) estimates that 23.5 million Americans are now affected, with the American Autoimmune Related Diseases Association (AARDA) putting the estimate even higher, at 50 million. “Some autoimmune disorders, such as type 1 diabetes and autoimmune thyroid disease, are thought to be on the rise,” says Emily Somers, PhD, an epidemiologist at the University of Michigan’s School of Public Health. “These changes over time suggest that environmental factors are involved.” Find out the difference between type 1 and type 2 diabetes.
They affect young women most frequentlyKjetil-Kolbjornsrud/Shutterstock
Dr. Cihakova says about 80 percent of people with autoimmune conditions are women, with some diseases like Sjogren’s syndrome having a women-to-men ratio as high as 9:1. The U.S. Department of Health and Human Services‘ Office on Women’s Health says these conditions tend to develop during the childbearing years. “Females have a higher susceptibility to autoimmune diseases than men—in fact, autoimmune diseases as a group rank among the leading 10 causes of death for women,” Dr. Somers says. “For many years it was assumed that hormones such as estrogen were involved, but more recently, it has been suggested that genetic factors linked to the X chromosome may be involved.” Because females have two X chromosomes while men only have one, the second may give an extra “dose” of X that may make women more susceptible to X-linked conditions. A recent study from the University of Michigan showed how different genetic expressions in women could increase their chances of autoimmune-related diseases. Plus, ” females and males often differ in their susceptibility to the effects of environmental agents” that might impact autoimmunity, Dr. Somers says. But overall, the reason for the sex disparity is “a mystery,” she says. Read how one woman beat the chronic pain of the autoimmune condition multiple sclerosis.