In addition to the coestablished roles of BDNF in modulating neuroplasticity in neurodegenerative diseases and depression, a few other fundamental factors that may have a profound effect in such diseases are currently being explored, such as miRNAs, a class of small noncoding RNAs that can typically bind to the 3′-UTRs of mRNAs to induce repression or degradation. Here, BDNF is linked to major depressive disorder.