Association between atopic dermatitis and attention deficit hyperactivity disorder in U.S. children and adults.

BACKGROUND: Atopic dermatitis (AD) is associated with chronic itch, allergic disease and sleep disturbance, all of which might increase the risk of attention deficit (hyperactivity) disorder (ADD/ADHD). Previous analyses have found a consistent association between AD and ADD/ADHD, although the underlying factors contributing to such an association remain underexplored. Additionally, the relationship has been underexplored in adults. OBJECTIVES: To determine if childhood and adult AD and AD severity are associated with ADD/ADHD and to delineate the factors contributing to such an association. METHODS: We analysed data on 354 416 children aged 2-17 years and 34 613 adults age 18+ years from 19 U.S. population-based surveys, including the National Health Interview Survey 1997-2013 and the National Survey of Children's Health 2003/4 and 2007/8. RESULTS: In multivariate models adjusting for age, sex, sociodemographics, allergic disease and healthcare utilization, AD was associated with ADD/ADHD in both children [adjusted odds ratio (95% confidence interval), 1·14 (1·03-1·26)] and adults [1·61 (1·25-2·06)]. Children with both severe AD and only 0-3 nights of adequate sleep per week had much higher odds of ADD/ADHD [16·83 (7·02-40·33)] than those with 0-3 nights of adequate sleep per week [1·83 (1·47-2·26)] or mild-moderate AD alone [1·56 (1·22-1·99)]. AD was most strongly associated with severe ADHD. AD unaccompanied by other allergic disease was also associated with increased risk of ADD/ADHD in children. Among children with AD, history of anaemia, headaches and obesity were associated with even higher odds of ADD/ADHD. Asthma, insomnia and headaches increased the odds of ADHD in adults with AD, although underweight body mass index was protective. CONCLUSIONS: Atopic dermatitis is associated with increased odds of ADD/ADHD in adults and children. Several factors increase the risk of ADHD in adults and children with AD.

Naturally occurring tolerance acquisition to foods in previously allergic children is characterized by antigen specificity and associated with increased subsets of regulatory T cells.

BACKGROUND: Food allergy affects approximately 6-8% of children, and increasing in prevalence. Some children naturally outgrow their food allergy without intervention, but the mechanisms by which this occurs remain poorly understood. We sought to investigate the role of regulatory T cells in the development of naturally acquired tolerance. METHODS: Fifty-eight children (1-18 years) with either egg or peanut allergy, recent acquisition of natural tolerance to egg or peanut, or no food allergy were studied. Peripheral blood mononuclear cells (PBMC) from these groups were stimulated with relevant antigen for 48 h and flow cytometry performed to characterize both surface (CD3, CD4, CD25, CD14, CD19, and CD127) and intracellular markers (IL-10, Foxp3, and IL-5). RESULTS: Resting PBMC from naturally tolerant patients had significantly increased CD3+CD4+CD25+CD127loFoxp3+ cells, when compared to allergic or control patients (mean 6.36 vs. 2.37 vs. 2.62%, respectively, P < 0.05). Upon stimulation with relevant antigen, naturally tolerant patients also had increased IL-10-expressing CD25+CD127lo cells (6.33 vs. 1.65 vs. 0.7, P < 0.01), Foxp3+ cells (mean 12.6 vs. 5.42 vs. 3%, P < 0.01), and CD4+ cells (mean 4.48 vs. 1.59 vs. 0.87%, P < 0.01); the increase was not observed in PBMCs from allergic or control patients. Additionally, this upregulation was only seen with relevant antigen stimulation and not upon stimulation with unrelated antigen. CONCLUSION: The increased CD3+CD4+CD25+CD127lo cells at baseline and upon stimulation and increased induction of IL-10-producing cells of several types, including Tr1 cells, from naturally tolerant patients suggests an important role for regulatory T cell subsets in the acquisition of natural tolerance.