Cross-sectional study of neutrophil-lymphocyte, platelet-lymphocyte and monocyte-lymphocyte ratios in mood disorders.

OBJECTIVE: Neutrophil-lymphocyte, monocyte-lymphocyte and platelet-lymphocyte ratio are inexpensive and reproducible biomarkers of inflammation found to be elevated in mood disorders. This study aimed to compare inflammatory ratios between bipolar disorder and major depressive disorder and between bipolar disorder manic episodes and bipolar disorder depressive episodes. METHOD: We included 142 Caucasian patients (major depressive disorder: n = 36; bipolar disorder manic episode: n = 66; bipolar disorder depressive episode: n = 40). We measured white blood cells, neutrophils, lymphocytes, monocytes, platelets, glucose, and total cholesterol. Neutrophil-lymphocyte ratio, monocyte-lymphocyte ratio, and platelet-lymphocyte ratio were calculated. RESULTS: Neutrophil-lymphocyte ratio and monocyte-lymphocyte ratio were significantly higher in bipolar disorder manic episodes when compared to bipolar disorder depressive episodes and major depressive disorder episodes after adjustment for age, sex, body mass index, and smoking. CONCLUSION: To our knowledge, our study is the first one to compare inflammatory ratios between different bipolar disorder phases and major depressive disorder episodes. In accord with previous studies on other inflammatory mediators, we found higher neutrophil-lymphocyte and monocyte-lymphocyte ratios in bipolar manic episodes, suggesting that inflammatory changes occur especially during acute episodes of mania.

Neutrophil/lymphocyte ratio and platelet/lymphocyte ratio in mood disorders: A meta-analysis.

The immune and inflammatory system is involved in the etiology of mood disorders. Neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and monocyte/lymphocyte ratio (MLR) are inexpensive and reproducible biomarkers of inflammation. This is the first meta-analysis exploring the role of NLR and PLR in mood disorder. We identified 11 studies according to our inclusion criteria from the main Electronic Databases. Meta-analyses were carried out generating pooled standardized mean differences (SMDs) between index and healthy controls (HC). Heterogeneity was estimated. Relevant sensitivity and meta-regression analyses were conducted. Subjects with bipolar disorder (BD) had higher NLR and PLR as compared with HC (respectively SMD = 0.672; p < 0.001; I2 = 82.4% and SMD = 0.425; p = 0.048; I2 = 86.53%). Heterogeneity-based sensitivity analyses confirmed these findings. Subgroup analysis evidenced an influence of bipolar phase on the overall estimate whit studies including subjects in manic and any bipolar phase showing a significantly higher NLR and PLR as compared with HC whereas the effect was not significant among studies including only euthymic bipolar subjects. Meta-regression showed that age and sex influenced the relationship between BD and NLR but not the relationship between BD and PLR. Meta-analysis was not carried out for MLR because our search identified only one study when comparing BD to HC, and only one study when comparing MDD to HC. Subjects with major depressive disorder (MDD) had higher NLR as compared with HC (SMD = 0.670; p = 0.028; I2 = 89.931%). Heterogeneity-based sensitivity analyses and meta-regression confirmed these findings. Our meta-analysis supports the hypothesis that an inflammatory activation occurs in mood disorders and NLR and PLR may be useful to detect this activation. More researches including comparison of NLR, PLR and MLR between different bipolar phases and between BD and MDD are needed.