MicroRNAs (miRNAs), a class of small, non-coding RNA molecules with gene regulatory functions, have emerged to play a critical role in the pathogenesis of a variety of diseases. Recently, circulating miRNAs have been reported as potential biomarkers for various pathologic conditions. The present study was performed to investigate the potential role of circulating miRNAs as diagnostic biomarkers for mild cognitive impairment (MCI). We collected 66 patients with MCI and 76 normal controls from our previous cross-sectional cohort study. Seven miRNAs (miR-206, miR-132, miR-193b, miR-130b, miR-20a, miR-296, and miR-329) related to Alzheimer's disease (AD) were detected in serum using a quantitative real-time PCR (qRT-PCR) method. Each miRNA's diagnostic performance was evaluated by receiver operating characteristic curves and the areas under curves (AUC) analysis. The levels of miR-206 and miR-132 in MCI patients' serum were significantly elevated compared to normal controls. Combining detection of miR-206 and miR-132 achieved the highest AUC of 0.981, followed by test of miR-206 (AUC = 0.880) and miR-132 (AUC = 0.912) separately. Importantly, miR-206 and miR-132 were respectively correlated with the Montreal Cognitive Assessment score in MCI patients. These results preliminarily indicated that circulating miR-206 and miR-132 as novel miRNAs upregulated in MCI patient were potential biomarkers for diagnosis of MCI.
Keywords: Biomarkers; diagnosis; microRNA; mild cognitive impairment; serum.