A new study found that people with atopic dermatitis are more likely to develop inflammatory bowel disease, including ulcerative colitis and Crohn's disease.
Atopic dermatitis, or eczema, is an inflammatory skin condition that leads to itchy, red patches on the skin's surface. The condition impacts about 10% of people in the United States. However, reports suggest eczema cases are increasing among children.
Inflammatory bowel disease (IBD) includes conditions like Crohn's disease and ulcerative colitis. Symptoms of IBD include diarrhea, abdominal pain, cramping, and weight loss. Although the exact number is unknown, experts estimate that around 1.3% of the population has one of these bowel disorders.
While eczema affects the skin and IBD is a digestive tract condition, both involve severe inflammation and changes in the immune system.
Recently, scientists from the Perelman School of Medicine at the University of Pennsylvania discovered that eczema may be linked to IBD.
Their research, which appears in JAMA Dermatology, found that adults and children with atopic dermatitis have a higher risk of developing IBD, including Crohn's disease and ulcerative colitis.
To conduct the research, the scientists used data from 409,431 children and 625,083 adults with atopic dermatitis. The participants were matched with individuals without eczema and categorized by eczema severity.
Previous research has examined the association between eczema and IBD, but this investigation looked at links between eczema severity and the risk of IBD, ulcerative colitis, and Crohn's disease separately.
The scientists found that children with atopic dermatitis had a 44% increased risk of IBD and a 74% increased risk of Crohn's disease. As the severity of eczema increased, so did the risk for IBD and Crohn's. For example, if a child had severe atopic dermatitis, their risk of Crohn's disease was five times higher.
However, the researchers found no link between atopic dermatitis and an increased risk of ulcerative colitis unless the eczema was severe.
Among adult participants, the scientists found that those with atopic dermatitis had a 34% increased risk of IBD, a 36% higher risk of Crohn's disease, and a 32% increased risk of ulcerative colitis. Moreover, the risk increased as eczema severity worsened.
According to the study authors, "shared genetic and environmental factors, immune cell activation, and alterations in skin and gut microbiota" might explain the association between eczema and IBD.
"Atopic dermatitis and IBD can cause changes in the microbiome, chronic inflammation, and the dysfunction in the skin and gut barrier respectively," said senior author Joel M. Gelfand, M.D., the James J. Leyden, M.D. Endowed Professor in Clinical Investigation in the Department of Dermatology at Penn.
"There are also specific cytokines, certain kinds of proteins, that play a role in immune system activity and that seem to be related to atopic dermatitis and IBD," Gelfand adds. "For example, we think dysfunction of types of T cells common to both atopic dermatitis and IBD, could be the culprits. Those need to be explored further to uncover both what's happening at a microscopic level and what proteins or structures could be targeted to treat one or both conditions."
Still, Gelfand says the absolute increased risk of developing IBD is small among individuals with eczema. However, with the sheer number of people impacted by the skin condition, healthcare professionals should be aware of the risks, particularly when choosing systemic atopic dermatitis treatments for people exhibiting inflammatory bowel disease symptoms.
- JAMA Dermatology. Risk of Inflammatory Bowel Disease in Patients With Atopic Dermatitis.
- Penn Medicine News. Inflammatory Bowel Disease Linked to Atopic Dermatitis, Penn Medicine Research Finds.