Association between allergic sensitization and attention deficit hyperactivity disorder (ADHD)

The increase in prevalence and burden of allergic diseases, i.e., eczema, asthma, and rhinitis, has been matched by parallel trends in a worldwide increase in attention deficit hyperactivity disorder (ADHD) diagnoses. Research data concerning the causal association between ADHD and allergies are conflicting. Allergic sensitization is the most important risk for development of allergic diseases.

We investigated the relationship between allergic sensitization in patients with physician-diagnosed ADHD.

Eighty patients were enrolled in the study. Forty patients were allocated into the ADHD group who presented with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnosis of ADHD to an outpatient pediatric developmental and behavioral clinic and the other 40 were enrolled in the control group. All patients were performed skin prick testing to common allergens and were evaluated for allergic diseases with focused history and physical examination.

The prevalence of any positive skin prick test (SPT) in ADHD patients was higher than the control, 67.5% and 45.0%, respectively. (p = 0.043) The five most common sensitizing allergens were as follows: D. farinae, 42.5 %, D. pteronyssinus 40.0%, Bermuda grass 37.5%, American cockroach 35.0%, German cockroach 30.0% and Johnson grass 30.0% in ADHD children D.farinae 32.5 %, D. pteronyssinus, 32.5%, German cockroach 22.5%, American cockroach 20.0% and Bermuda grass 20.0% in control children. No significant differences were detected between the groups on type of allergen except Johnson grass. Sensitization to Johnson grass was significantly higher in the ADHD group, 30.0% in ADHD cases and 10.0% in control cases. (p = 0.048) The frequency of allergic rhinitis was higher in the ADHD group. (p = 0.008) No differences between groups were observed regarding other allergic diseases, asthma, eczema, allergic conjunctivitis, food allergy and urticaria. (p > 0.05)

Our results suggest that there were increased rates of allergic sensitization and allergic rhinitis in ADHD children. Therefore, assessment of allergic sensitization may be beneficial in children diagnosed with ADHD.