Increased Serum Level of CCL5 in Children with Attention‑Deficit/Hyperactivity Disorder: First Results about Serum Chemokines.

Objective: Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder and its aetiology is not fully understood. This study aimed to determine whether the CCL5 and CCL11 influence the ADHD aetiology by comparing serum CCL5 and CCL11 levels of children with ADHD and typical development.

Methods: This study included 45 (27 males, mean age = 8.9 ± 1.7 years) treatment-naive patients diagnosed with ADHD and 35 (20 males, mean age = 8.8 ± 1.6 years) healthy controls. Participants ranged in age between 6-12 years and completed the Conners Teacher Rating Scale that assesses ADHD presentation and severity. CCL5 and CCL11 serum levels were also measured using enzyme-linked immunosorbent assay kits.

Results: Significantly higher serum CCL5 levels were found in children with ADHD compared to healthy controls ( < 0.001). No significant difference was found between the mean serum CC11 level of the patients and controls ( = 0.93). In addition, there was no significant correlation between the serum CCL5 and CCL11 levels and predominant presentations of ADHD and disease severity.

Conclusion: This study suggests that there are higher levels of serum CCL5 in drug naive children with ADHD, this findings suggest that CCL5 might play a role in the pathophysiology of ADHD. Moreover, these changes in peripheral blood may have therapeutic value. In addition, these results help to understand the role of chemokines in elucidating the etiopathogenesis of ADHD. Our results can be considered as the first step in investigating the role of CCL5 in ADHD, and further research is needed to support these initial findings.