This mechanism underscores a broader neurotrophic dimension to MDD, where chronic stress and depression are associated with a loss of synaptic integrity and an imbalance between pro-survival factors (like mature BDNF, brain-derived neurotrophic factor) and pro-degenerative signaling pathways (e.g., via p75 neurotrophin receptor) [45]. The gene discussed is BDNF; the disease is major depressive disorder.