Immune Biomarkers Identified in Patients With Bipolar Disorder During Manic Episodes

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The immune system dysregulation may lead to or exacerbate neuropsychiatric conditions such as bipolar disorder.

Researchers evaluated the potential of a diagnostic biomarker blood test for bipolar disorder.
Researchers evaluated the potential of a diagnostic biomarker blood test for bipolar disorder.

Research efforts throughout recent years have revealed that the immune system dysregulation triggers pathophysiologic changes of the central nervous system, which may then lead to or exacerbate serious neuropsychiatric conditions such as bipolar disorder. A recent report published in Neuropsychiatric Disease and Treatment supports these notions, which implicate the aberrant immune system activity and systemic inflammation in patients diagnosed with bipolar disorder.

The association between neuropsychiatric disorders and platelet activation has previously been described. More specifically, platelets may indicate biochemical changes in the brain across various psychiatric conditions. In the current study, investigators compared mean platelet volume, the accurate measure of platelet size and an indicator of platelet function, in patients diagnosed with bipolar disorder according to the DSM-IV (n=132), with that of age- and sex-matched typical, healthy control participants (n=135). Only patients with manic episodes during admission were included in the analyses.

The patients' hemogram values included: white blood cell (WBC), neutrophil, lymphocyte, platelet, and red blood cell (RBC) counts, as well as hemoglobin, hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW), MPV, and plateletcrit (PCT). Researchers used the peripheral venous blood samples to perform the analysis because the central nervous system is difficult to access.

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Results show that there were significant differences in the mean WBC count, as well as in the median NLR (ie, the ratio of the absolute neutrophil-to-lymphocyte counts), PLR (ie, the ratio of the absolute platelet-to-lymphocyte counts), neutrophil, lymphocyte, MPV, and PCT values, between the patients with bipolar disorder and control participants. More specifically, the mean count, and the median values, of the above measures were significantly greater among patients with bipolar disorder compared with those of controls. Conversely, hemoglobin was significantly lower in individuals with bipolar disorder compared with that of controls. Researchers did not find statistically significant differences with regard to the MCV, MCH, RDW, or platelet values.

Thus, these data support the hypothesis that the aberrant immune system function occurs in patients with bipolar disorder during manic episodes, and “the development of new preventive and therapeutic options can be expedited through the understanding of this mechanism because it is through this mechanism that inflammation may pathologically affect brain function and thereby induce and/or perpetuate bipolar disorder,” the authors concluded.

Reference

Mert DG, Terzi H. Mean platelet volume in bipolar disorder: the search for an ideal biomarker. Neuropsychiatr Dis Treat. 2016;12:2057-2062.

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