Serum Levels of Interleukin-6 and Tumor Necrosis Factor Alpha in Children With Attention-Deficit Hyperactivity Disorder.

Background: Attention-deficit hyperactivity disorder (ADHD) is a common disorder in children, but its etiology and pathogenesis are still unclear.

Aims: The aims of this study were to measure the level of serum interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) as markers of immune system involvement in children with ADHD, and to study their correlation with symptoms severity of ADHD.

Materials And Methods: The study was conducted on 80 children diagnosed as ADHD based on the criteria adapted from the . Eighty healthy children of matched age and sex served as a control group. All children enrolled in the study were subjected to history taking, clinical examination, and psychometric tests. Assay for serum IL-6 and TNF-α for all patients and controls was performed using enzyme-linked immunosorbent assay.

Results: The mean serum level of IL-6 was 26.11 ± 11.14 and 6.23 ± 2.52 in children with ADHD and controls, respectively. Children with ADHD showed significantly higher serum IL-6 levels than the control group ( = 0.001). Serum IL-6 showed no significant correlation with the intelligence quotient (IQ) or the Abbreviated Conners' Rating Scale scores for parents. However, TNF-α showed no significant differences between the two groups and no significant correlation with the IQ or the Abbreviated Conners' Rating Scale scores for parents.

Conclusion: Serum IL-6 levels were significantly higher in children with ADHD compared to controls; however, the IL-6 levels did not correlate with ADHD symptoms severity. Increased IL-6 levels may contribute to the etiology of ADHD.