Serum Interleukin-6 Level in Children With Attention-Deficit Hyperactivity Disorder (ADHD)

Introduction: Attention-deficit hyperactivity disorder (ADHD) is a common neurobehavioral disorder in children, but its specific etiology and pathophysiology are still incompletely understood. Objectives: This case-control study aimed to measure the level of serum interleukin-6 (IL-6) as a predictor of the immunologic status in children with ADHD, and to study its correlation with severity of symptoms. Subjects and Methods: 60 ADHD children who met the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, criteria for ADHD and 60 control children were subjected to complete history taking, clinical examination, and psychometric tests. Serum interleukin-6 of ADHD patients and control children was measured by enzyme-linked immunosorbent assay. Results: The mean serum level of IL-6 was 22.35 (95% confidence interval [CI], 17.68-26.99) in ADHD patients, and it was 5.44 (95% CI, 4.81-6.06) in controls. A significantly higher level of IL-6 was reported in ADHD patients compared with controls (P =.001). No significant correlation was found between serum IL-6 level and either the Intelligence Quotient (IQ) or the Conners’ Parent Rating Scale score. Conclusion: Serum IL-6 values were significantly higher in ADHD patients compared to healthy control children. Increased production of IL-6 may play a role in the pathogenesis of ADHD.