Association Between Mood Disorder Severity, Treatment Response and Systemic Inflammatory Markers: Exploring the Role of NLR, PLR, MLR, and SII

Background: In this study, the relationship between treatment response, clinical features of episodes such as psychosis, suicidal behavior, and agitation, duration of hospitalization, and systemic inflammation markers Systemic Inflammatory Index (SII), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) in bipolar affective disorder manic episode (BAD-M), bipolar affective disorder—depressive episode (BAD-D), and major depressive disorder (MDD) were investigated.

Methods: The NLR, MLR, PLR, and log SII were measured using parameters from a complete blood count. Admission and discharge Young Mania Rating Scale and Hamilton Depression Rating Scale scores were evaluated. This is a retrospective study conducted with a total of 451 inpatients, 122 (27.10%) of whom were diagnosed with BAD-M, 60 (13.20%) with BAD-D, and 269 (56.60%) with MDD.

Results: The patients with manic episodes have higher levels of NLR (P=.019), MLR (P=.002), and log SII (P=.007). In the bipolar depression and mania groups, the patients with and without treatment responses did not differ in terms of inflammation markers; the log PLR value was found to be higher in the unipolar depression group in the patients who did not reach remission (P=.048).

Conclusion: This study reveals associations between inflammation markers and different types of mood episodes. Higher NLR, MLR, and log SII levels in bipolar mania and lower NLR levels in agitated unipolar depression provide clues about changes in inflammation across different episodes. Studies with larger samples are needed to evaluate the relationship between inflammatory markers, the severity of mania and depression, and the response to treatment.

Cite this article as: Kucukkarapinar M, Erbil D, Keles İ, Karadag F. Association between mood disorder severity, treatment response and systemic inflammatory markers: Exploring the role of NLR, PLR, MLR, and SII. Psychiatry Clin Psychopharmacol. 2024;34(1):19-28.