J Korean Soc Biol Ther Psychiatry.  2022 Oct;28(3):119-126.

Inflammatory Biomarkers and Bipolar Disorder: Neutrophil/Lymphocyte Ratio, Monocyte/Lymphocyte Ratio and Platelet/Lymphocyte Ratio

• Heo J
• Lee Y

Abstract

Objectives
：Neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR), and platelet/lymphocyte ratio (PLR) are indicators of inflammation. Several studies have evaluated their relationship with bipolar disorder severity, but the results are controversial. Here, we investigate the relationship between inflammatory ratios and the severity and clinical characteristics of bipolar disorder.
Methods
：We retrospectively reviewed the medical records of bipolar disorder patients who met the inclusion criteria and admitted to Kosin University Gospel Hospital between January 2010 and August 2021. NLR, MLR and PLR were measured according to the complete blood count. Severity was assessed by the Young Mania Rating Scale (YMRS) in hypo/manic episode patients, the Hamilton Rating Scale for Depression (HAMD) in depressive episode patients. Patients are grouped by presence of two clinical features, current psychotic features and history of suicide attempts.
Results
：181 subjects, of whom 123 were women and 58 men, were included. Subjects with higher NLR had higher HAMD scores (N=36, r=0.337, p=0.045). We found no significant correlation between YMRS and the inflammatory biomarkers. Patients with previous suicide attempts exhibited a greater PLR than those without previous suicide attempts (N[SA+]=52, N[SA-]=129, p=0.035). There was no significant difference in inflammatory ratios with respect to psychotic features.
Conclusions
：We found a possible correlation between the severity of bipolar depression and inflammatory indicators in the Korean population, in addition to correlation between previous suicidal attempt of bipolar disorder and inflammatory indicators. A well-designed prospective study involving a larger cohort is needed in the future.

Keyword

Bipolar disorder; Neutrophil/lymphocyte ratio; Platelet/lymphocyte ratio; Depression; Suicide attempt