In addition, miRNA and circRNA can restore their abnormal functions in depression by regulating specific signals, which may imply the impairment of genes implicated in pathways of MDD etiopathogenesis, such as neuroinflammation, brain-derived neurotrophic factor (BDNF), neurotransmitters, hypothalamic–pituitary–adrenal (HPA) axis, PI3K/Akt signal, and et al. [14]. Here, BDNF is linked to depressive symptom measurement.