Neutrophil-to-lymphocyte ratio and platelet distribution width: A potential new peripheral biomarker in adolescent depression

Objective: The aim of this study is to evaluate the role of inflammation in the underlying pathophysiology of ado-lescent depression by evaluating neutrophile-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and hemogram parameters and also to determine whether there is a relationship between depression severity and inflammatory parameters. Method: This retrospective study was carried out on 93 major depressive disorder (MDD) patients and 65 healthy control. Clinical features such as diagnosis date, diagnosis during admission to hospital using DSM-5 diagnostic criteria, comorbid phys-ical and psychiatric illness, drug use, previous psychiatric diagnosis, history of suicide attempt were determined. In addition, hemogram parameters of the participant included in the study in the hospital data system were used. Results: NLR and platelet distribution width (PDW) were found to be statistically significantly higher in the patient group than in the control group (p<0.05). A weakly significant positive correlation (p =0.039, r=0.165) was found between NLR and depression seve-rity scale; a positive correlation was found between PDW and depression scale scores and depression severity scale total scores (p<0.001, r=0.317; p<0.001, r=0.320, respectively). Discussion: NLR and PDW were found to be significantly higher in patients with MDD than in healthy controls, and it supports the possible role of low-grade inflammation in the pathophysiology of MDD. In the next years, prospective studies in which hemogram parameters are evaluated together with proinflammato-ry cytokines will more clearly illuminate the role of inflammation and platelet activation in the etiology of MDD in adolescents.