Plasma miRNA Profiles in Chronically Treated Bipolar Disorder Patients: A Case–Control Study

Objective: This study aimed to determine the molecular repercussions of chronic treatment and potential biomarker candidates by comparing the expression profiles of 34 selected miRNAs in peripheral plasma of patients with bipolar disorder receiving pharmacotherapy for at least one year with healthy controls. Methods: The study included 40 patients with bipolar disorder and 40 age- and sex-matched healthy controls. The miRNA fraction was obtained from plasma samples isolated from peripheral blood. 34 target miRNAs were quantified on the Biomark Real-Time PCR Dynamic ArrayTM IFC platform. Control and bipolar groups were compared based on Ct values. Results: After applying multiple comparison corrections, we found that the following miRNAs significantly decreased in the bipolar group: hsa-miR-222-3p, hsa-miR-574-3p, hsa-miR-145-5p, and hsa-miR-195-5p. Conversely, hsa-miR- 25-3p exhibited an increase. The most notable increases were seen in hsa-miR-92a-3p, with a fold change of 1.25 (p ＜ 0.001; q = 0.009), and hsa-miR-486-5p, with a fold change of 1.67 (p = 0.002; q = 0.033). Additionally, other miRNAs showed raw p values less than 0.05, but they lost statistical significance after false discovery rate correction. Conclusion: Peripheral plasma miRNA profiles in chronic bipolar disorder revealed elevated miR-92a-3p and miR-486-5p and decreased miR-222-3p, miR-574-3p, miR-145-5p and miR-195-5p. These miRNAs may be suitable for evaluation as minimally invasive biomarker candidates in bipolar disorder, and their potential clinical use in diagnosis, prognosis, and treatment monitoring should be investigated with further studies.