Association of Allergic Diseases and Attention Deficit Hyperactivity Disorder in Children: A Large-Scale Cohort Study

Background: The burden of attention deficit hyperactivity disorder (ADHD) has increased during the last few decades, as in allergic disorders. In some observational studies, ADHD has been linked to allergic diseases, but the evidence remains limited. The aim of this study was to investigate whether allergic disorders are associated with ADHD in a large cohort of patients. Methods: : Data from this cohort was retrieved from 860,089 children aged 5 to 16 years of age and collected from the pediatric database from Health Services of İzmir, Turkey, recorded from January 1, 2013, to December 31, 2023, and analyzed. The person-years and the association between allergic disorders (respiratory, skin, other allergies including food, drug, allergies and anaphylaxis and any of these) and ADHD were estimated by relative risks. Results: : The incidence of allergic disorders in the last 11 years was 7.8% (64,137 cases). Respiratory allergies (61,728; 6.7%) were the most common, followed by skin allergies (7,152; 0.9%). The other allergy group (2031 cases; 0.2%) was the least common, including anaphylaxis, food and drug allergies. The incidence of ADHD was determined as 5.3% and, as expected, was more common in boys (7.2%). The relative risk estimations showed a positive association between allergy groups and ADHD (RR 1.99, 95% CI 1.96-2.02) for both genders. A positive association was not observed only in the boy group with the other allergy group (RR 1.13, 95% CI 0.99-1.29). Conclusion: An association between allergic disorders and ADHD has been observed. Considering the nature of the data population-based cohorts might be suggested.