Comparison of bipolar disorder patients with healthy controls in terms of inflammatory biomarkers

OBJECTIVE: The available evidence suggests that the main pathological processes underlying Bipolar Disorder and the potential harmful effects of mood episodes are closely related to changes in disorder activity and mood status. Although there are several studies on the existence of a relationship, the results are contradictory. Inflammatory changes occur in various episodes of Bipolar Disorder (BD) Type 1. These changes can be considered as peripheral symptoms of the disorder. In this study, we aimed to compare the inflammatory biomarkers in the BD patients in the manic, depressive and euthymic period with the healthy controls.

METHODS: Interleukins (IL) and tumour necrosis factor (TNF) values were measured and compared in 78 healthy controls with 108 patients with BD.

RESULTS: There was a statistically significant difference between the patient and control groups in terms of age (p = .040) and educational status (p = .002). There were no statistically significant differences between the BD subgroups with regard to clinical variables such as the age of onset (p = .862), duration of disease (p = .389) and the age of hospitalization (p = .092). In the subgroup of mania, the rate of psychiatric hospitalization was higher than depression or other subgroups (p = .047). When the blood values of peripheral biomarkers (IL-2, IL-4, IL-8, IL-10 and TNFα) were compared, there was no statistically significant difference between the values of the peripheral biomarkers of all BD patients and the control group. The levels of IL10 were higher in the control group than in the BD group, but not statistically significant.

CONCLUSIONS: As a result, there was no statistically significant difference between the two groups when comparing serum concentrations of basic IL and TNF in the BD group and control group. There was no difference in the comparison among the patient groups. IL-2 and IL-4 and manic episodes of IL-2 in manic episode were not significant. Therefore, in order to clarify the relationship between inflammatory biomarkers in BD and its possible association with pharmacological treatments, biomarker measurements are required in larger patient samples and ideally at different mood stages and even at different times of the same attack.