Regarding miRNA alterations, the abundances of specific genera such as Bacteroides and Dialister in MDD patients were highly correlated with the expression of several miRNAs involved in the function of MDD-associated and neurotrophins signaling pathway, circadian rhythm, and dopaminergic synapses among others [73] addressing the involvement of microbiota-miRNA interactions in the microbiota-gut-brain axis. This evidence concerns the gene BDNF and major depressive disorder.