Conversely, serotonin regulates BDNF expression through its effects on neurogenesis and synaptic transmission. Disruptions in this interaction can contribute to mood disorders [9,10]. Serotonergic drugs, like selective serotonin reuptake inhibitors (SSRIs), increase serotonin activity, which in turn elevates BDNF levels, supporting neuronal health and improving mood [11]. This evidence concerns the gene BDNF and mood disorder.