Elevated neutrophil-to-lymphocyte ratio in children and adolescents with attention-deficit/hyperactivity disorder

Abstract

Objective Inflammation is reported to play a substantial role in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). Neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) are inexpensive and potentially interesting biomarkers of inflammation. In this cross-sectional and retrospective study, we investigated the relationship between NLR, PLR and ADHD. Methods This study consisted of 100 children and adolescents with ADHD (85 of those receiving psychopharmacological treatment), and 99 physically and mentally healthy children. Results The mean NLR and PLR were significantly higher in patients than in controls. There was no significant difference between patients who received psychopharmacological treatment for ADHD and patient that did not with regard to NLR and PLR. No associations were found between NLR and PLR and ADHD symptom severity. The significance of NLR is not influenced by medication use, age and sex. Conclusions Our findings suggest that NLR and PLR may be inflammation biomarkers in children and adolescents with ADHD. Moreover, the significance of NLR is not influenced by medication use, age and sex. Prospective studies that address alterations in NLR and PLR and other pro-inflammatory cytokines following ADHD treatment may provide additional information about the inflammatory mechanisms in ADHD. Key points The mean NLR and PLR were significantly higher in patients than in controls. The significance of NLR is not influenced by medication use, age and sex. No associations were found between NLR and PLR and ADHD symptom severity. Prospective studies that address alterations in NLR and PLR and other pro-inflammatory cytokines following psychopharmacological treatment of ADHD may provide additional information about the inflammatory mechanisms in ADHD