Increased attention-deficit/hyperactivity symptoms in atopic dermatitis are associated with history of antihistamine use.

BACKGROUND: Epidemiologic evidence indicates a relevant association between atopic dermatitis (AD) and attention-deficit/hyperactivity disorder (ADHD). Underlying mechanisms and ways to best identify subgroups of AD patients at risk for ADHD are poorly understood.

AIMS OF THE STUDY: To compare sociodemographic, clinical and psychosocial characteristics of children with AD, ADHD, comorbid AD/ADHD and age-matched healthy controls and to investigate aspects of AD related to ADHD symptoms.

METHODS: Applying a factorial design, we investigated 4 groups of children aged 6-12 years: AD-only (ie, without ADHD), ADHD-only (ie, without AD), AD + ADHD and healthy controls (HC; ie, no AD/no ADHD). Using validated instruments, ADHD symptoms and other behavioural problems, quality of life, parenting stress and sleeping problems were compared between groups. In children with AD-only, clinical signs (objective SCORAD), symptoms (POEM, VAS pruritus, VAS sleeping problems) and previous treatment of AD were assessed to investigate disease patterns related to ADHD symptoms.

RESULTS: Compared to HC (n = 47), children with AD-only (n = 42), ADHD-only (n = 34) and comorbid AD + ADHD (n = 31) had significantly increased behavioural problems and decreased quality of life. Children with AD-only had significantly higher levels of ADHD symptoms than HC. In children with AD-only, previous use of antihistamines was significantly associated with increased ADHD symptoms (OR 1.88; 95% CI 1.04-3.39). Current clinical signs and AD symptoms were unrelated to the level of ADHD symptoms.

CONCLUSIONS: Even if the clinical diagnosis of ADHD is excluded, children with AD show increased levels of ADHD symptoms. Further investigations need to determine whether early antihistamine exposure is a major risk factor for ADHD or a surrogate for previous AD severity and/or associated sleeping problems.