Circulating miR-134 is a potential biomarker for diagnosis and monitoring of major depressive disorder.

to investigate the diagnostic value of circulating miR-134 in major depressive disorder (MDD). Plasma miR-134 levels were determined in patients with MDD, bipolar disorder (BD), and schizophrenia (SCZ), as well as in healthy controls using quantitative real-time PCR. The diagnostic value of circulating miR-134 was assessed using receiver-operator characteristic (ROC) curve analysis. A chronic unpredictable mild stress (CUMS) rat model was established to evaluate the miR-134 expression pattern in serum and diseased brain tissues. Plasma miR-134 levels in MDD patients were significantly lower than those in healthy controls and patients with BD or SCZ. In addition, plasma miR-134 levels could be used to discriminate MDD patients from healthy controls (areas under the curve (AUC) = 0.901), healthy controls + patients with BD or SCZ (AUC = 0.864), patients with SCZ (AUC = 0.856), patients with SCZ or BD (AUC = 0.828), and patients with BD (AUC = 0.799), respectively. In CUMS rats, the miR-134 levels in plasma (P < 0.001), prefrontal cortex (P = 0.031), and hippocampus (P = 0.006) were consistently reduced compared with those in control group, with the exception of those in olfactory bulb (P = 0.565). Circulating miR-134 a potential biomarker for MDD diagnosis and monitoring.