Background: Atopic dermatitis (AD) and attention-deficit/hyperactivity disorder (ADHD) are frequent paediatric conditions with high medical relevance. A possible relationship between atopic diseases (i.e., AD, asthma, and allergic rhinitis) has long been discussed, but convincing evidence is still missing.
Methods: We investigated the relationship between AD and ADHD in two cross-sectional studies and in two birth cohort studies considering lifestyle factors, environmental factors, and atopic comorbidities as potential confounders. To quantify the strength of association between AD and ADHD, data from the four epidemiologic studies were summarized by means of a meta-analysis. Odds ratios (OR) were pooled for the association between prevalent or previous AD and prevalent ADHD from the four studies adjusted for age, sex, and atopic comorbidity (allergic rhinitis, asthma).
Results: The epidemiologic studies conducted consistently indicate an association between AD and ADHD which is independent of environmental exposures and other comorbidities. Particularly infant AD appears to be associated with later development of ADHD symptoms. Sleeping problems due to AD are suggested as playing an important role for the observed association between AD and ADHD. The pooled OR (95 % confidence interval (95 %CI)) for the association between AD and ADHD was 1.43 (1.25-1.64).
Discussion: Four new epidemiologic studies consistently indicate a positive association between AD and ADHD. Compared to children without AD, children with previous or prevalent AD have an approximately 43 % increased risk to be diagnosed with ADHD or to display clinical ADHD symptoms. Following our findings, the biological mechanisms underlying the observed comorbidity between AD and ADHD require further investigation in order to subsequently develop targeted therapeutic and preventive strategies.