Introduction: With an increasing prevalence of major depressive disorder (MDD) in population there is a particular interest in finding a suitable biomarker for diagnosis and prognosis of the disease. Many studies have shown that MDD is linked to a systemic inflammatory process, so blood elements counts and ratios have been suggested to be promising indicators in the management and effectiveness of the disease therapy. The aim of this retrospective study was to compare absolute and relative white blood cells counts and to search for any changes in their ratios before and after the therapy of the patients.
Methods: Our study included 36 patients who were admitted to hospital with either a new diagnosis or a recurrent episode of MDD and who were treated by a standard protocol. The peripheral blood samples were collected both at admission and at hospital discharge. Absolute white blood cell count and counts of neutrophils, lymphocytes, monocytes, platelets, as well as mean platelet volume, red blood cell distribution width, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, and monocyte/lymphocyte ratio before and after hospitalization (14–29 days) were evaluated and compared. The test of normality was performed and, accordingly, single t-test or Mann-Whitney U-test was used for data analysis.
Results: There were no significant differences between any blood cell ratios in blood samples before and after stay in hospital and appropriate treatment. Monocyte count was significantly higher in MDD patients after hospital discharge (p=0.007), there was a significantly higher difference in discharged patients suffering from MDD recurrent episode (F.33) compared to newly diagnosed MDD (F.32) patients (p=0.010). In patients treated with venlafaxine (N=23) there was a significant increase in monocyte/lymphocyte ratio observed at the end of hospitalization (p=0.018).
Conclusions: The pharmacotherapy and additive treatment of the patients suffering from MDD led only to mild changes in blood cells counts. As our study included only a small number of patients, and blood cell parameters and ratios were compared after a relatively short duration of treatment, further and more detailed research is needed for final conclusions.
