Atopic dermatitis: Common type of eczema linked to higher risk of IBD - Medical News Today

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Experts note that atopic dermatitis can occur in children as well as adults. vladans/Getty Images

• Inflammation and immune factors associated with atopic dermatitis are also seen in people with a variety of autoimmune diseases, possible due to shared genetic and environment factors.
• Researchers from the University of Pennsylvania have found both children and adults with atopic dermatitis have an increased risk for inflammatory bowel disease (IBD).
• This risk varies depending on age, atopic dermatitis severity, and type of IBD.

About 223 million people around the world have atopic dermatitis — a chronic skin condition causing dryness, itching, and rash.

Of that number, about 43 million are children ages 1 to 4.

Atopic dermatitis is the most common type of eczema and because it is associated with inflammation, previous research shows people with this skin disease are at a higher risk for heart diseases, asthma, chronic kidney disease, and autoimmune diseases such as rheumatoid arthritis, celiac disease, and the two types of inflammatory bowel disease (IBD) — Crohn's disease and ulcerative colitis.

Now, researchers from the University of Pennsylvania are providing more insight into how atopic dermatitis increases a person's risk for IBD.

The scientists say they found that both children and adults with atopic dermatitis have an increased risk for IBD, however, the risk varies depending on age, atopic dermatitis severity, and type of IBD.

This study was recently published in the journal JAMA Dermatology.

Inflammatory bowel disease (IBD) is a term for two conditions (ulcerative colitis and Crohn's disease) that are characterized by chronic inflammation of the digestive tract.

It is an autoimmune disease, meaning the body's immune system mistakes healthy tissues in the digestive tract as something foreign, causing it to attack.

IBD refers to two main diseases:

• Crohn's disease causes inflammation of the lining of the digestive tract and can affect any area of the digestive system, including the mouth, esophagus, stomach, and intestines.
• Ulcerative colitis refers to inflammation and/or ulcers mainly in the large intestine.

Sometimes the distinction between Crohn's disease and ulcerative colitis cannot be made based on presenting symptoms and diagnostic tests. Their diagnosis is referred to as indeterminate colitis. A person may be initially diagnosed with one condition or the other, but over time their diagnosis can evolve into the other disease.

Researchers still do not know exactly what causes IBD. However, there are certain known risk factors for IBD including age, ethnicity, genetics, and environmental factors.

There is currently no cure for IBD.

However, the condition can be managed with a combination of lifestyle changes — including diet and managing stress — in addition to medications. Occasionally surgery to help alleviate symptoms.

According to Dr. Joel Gelfand, a professor in clinical investigation and the director of the Center for Clinical Sciences in Dermatology at the Perelman School of Medicine at the University of Pennsylvania and a senior author of this study, said his team decided to study the potential link between IBD and atopic dermatitis in both children and adults as another chronic skin condition called psoriasis has long been known to be associated with IBD and has some shared genetics.

"Less work has been done with atopic dermatitis, which is a very common skin disorder, and IBD," he told Medical News Today. "Both atopic dermatitis and IBD are diseases with barrier dysfunction, microbiome alterations, and chronic inflammation suggesting commonalities between the two diseases."

This is not the first study to look at a link between atopic dermatitis and IBD. A study of a Korean population published in 2020 found people with any atopic disease — including atopic dermatitis — were at an increased risk for developing IBD. The risk increased depending on how many atopic diseases a person had.

A study in 2022 found a causal link between atopic dermatitis and IBD, but not IBD and atopic dermatitis.

Conversely, a study published in 2021 reported atopic dermatitis was not independently associated with IBD development.

For this study, Gelfand and his team compared data from more than 409,000 children and 625,000 adults with atopic dermatitis and compared them to more than 1.8 million children and almost 2.7 million adults without the disease.

Upon analysis, the scientists reported a "statistically significant" increased risk of incident or new-onset IBD among 44% of children and 34% of adults with atopic dermatitis, compared to the control groups.

Additionally, researchers reported that the IBD risk increased with worsening atopic dermatitis severity.

"The results are important… the association is stronger with increasing severity of atopic dermatitis," Gelfand said. "I was a bit surprised that in children the association was stronger for Crohn's disease than ulcerative colitis."

"Both ulcerative colitis and atopic dermatitis are thought to be Th2 diseases, so we hypothesized a stronger relationship between atopic dermatitis and ulcerative colitis compared to atopic dermatitis and Crohn's disease," he added. "This finding is a reminder of the importance of epidemiological studies, which is the science of understanding the distribution and determinants of health in humans. It is not uncommon for biologically derived hypotheses to be reversed when studied in patients."

"The association in adults with more severe atopic dermatitis approaches the strength of association we see with psoriasis and IBD, which I think is a striking finding that needs more exploration," Gelfand noted.

Gelfand said he believes these findings are important for better understanding the health trajectories of people with atopic dermatitis.

"Treatments for atopic dermatitis are improving dramatically, but we will need to determine if these treatments reduce or increase (the) risk of other immune-mediated diseases over time," he explained. "For example, biologics that target IL4/13, such as dupilumab, can be incredibly effective for atopic dermatitis but also seem to induce other immune problems such as psoriasis and inflammatory arthritis in a small subset of patients."

"We have published a number of studies evaluating (the) risk of infection, neuropsychiatric disorders, cardiovascular disease, and malignancy risk in atopic dermatitis," Gelfand added. "We are trying to better understand long-term health outcomes for people with atopic dermatitis and the impact novel atopic dermatitis treatments have on overall health."

Medical News Today also spoke with Dr. Rudolph Bedford, a gastroenterologist at Providence Saint John's Health Center in California, about this study.

He said he was not surprised to hear about a link between atopic dermatitis and IBD as he does see patients with various skin manifestations in inflammatory bowel disease.

"They probably share some type of genetic predisposition in terms of the various genetic targets and that manifests in some type of pathophysiologic way in terms of developing either atopic dermatitis or some form of IBD," Bedford explained. "There is some type of immune cell activation, and I'm sure other environmental factors, and also the gut microbiota, that have something to do with the initiation of dermatitis, and then leading or eventually seeing inflammatory bowel disease."

"I think that certainly if dermatologists are more clued in, they might be able to identify more patients that may be predisposed to developing inflammatory bowel disease," he added. "Atopic dermatitis is a disease of children and adults, and it certainly may signal those patients with severe atopic dermatitis that are more likely… to have inflammatory bowel disease moving forward."

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