Investigating the Relationship Between Atopic Dermatitis and Irritable Bowel Syndrome

Abstract

Research Question: In a cohort of patients with atopic dermatitis (AD), is there an increased prevalence of irritable bowel syndrome (IBS) compared to the general population and if so, what might be the contributing factors in this relationship?

Background and Significance: AD is a chronic, recurrent inflammatory skin condition affecting 15-20% of children and 1-3% of adults worldwide.1 The hygiene hypothesis proposes that the rise in atopic disorders since the 1970s in developed countries is due to reduced “infectious pressure” from a Westernized lifestyle. Modern urban environments lack the microbial exposure which supports a diverse mucosal microbiome and promotes immunologic “priming.” For this reason, studies suggest a potential link between the microbiome and the development of atopic disorders, including asthma, allergic rhinitis, and AD. Although IBS affects an estimated 11.8% of the North American population2, the pathogenesis of IBS remains poorly understood. Evidence suggests a certain subtype of IBS may result from an imbalance in the microbial diversity in the gut, known as dysbiosis. Data strongly suggest that dysbiosis can signal an immune-related cascade in IBS. To our knowledge, no research has been done to evaluate the correlation between clinically diagnosed AD and IBS or the involvement of the microbiome in the development of both conditions. In this study, we investigated the relationship between IBS and AD in a cohort of subjects at board-certified dermatology offices. We also examined potential associations with selected covariates (e.g. demographic data, elements of past medical history, food intolerances) to further probe several secondary hypotheses.

Materials and Methods: Participants over the age of 12 were recruited and consented based on inclusion criteria, including a clinical diagnosis of AD made by a board-certified dermatologist. Study participants were surveyed for the presence of IBS and IBS-related symptoms according to the Rome IV Criteria. They were also asked about other predictors and aspects of the past medical history.

Results: The prevalence of IBS in our cohort of AD patients is 7.7%, compared to the estimated prevalence of IBS in the general population of 11.8%. However, we observed that a majority of individuals with AD experience regular abdominal discomfort (9/13, 69.2%) and food allergies, intolerances, and/or sensitivities (8/13, 61.5%). Among those with adult-onset AD, we observed all patients with adult-onset AD (3/3, 100%) also had lactose intolerance. Among those with childhood-onset AD, we observed 40% (4/10) patients also had nut allergies. There was no association with consumption of probiotic-rich foods or supplements, environment of upbringing, or mode of delivery at birth with the development of IBS in AD patients.

Conclusion: There was no association between AD and IBS as hypothesized when compared to the prevalence of IBS in the general population. However, a majority of patients with AD in this cohort develop gastrointestinal symptoms on a regular basis and a majority also develop food allergies, intolerances, and/or sensitivities. The data also supports that lactose intolerance is associated with adult-onset AD, and nut allergies are associated with childhood-onset AD.