In comparison with stroke, the main factors promoting MDD are psychosocial stressors, and the main pathophysiology of depression is associated with decreased monoamine levels, an altered hypothalamic-pituitary-adrenal axis [21], inflammation [22], neuro-plasticity and neurogenesis controlled by BDNF [22], and structural and functional brain changes (Fig. 2) [23, 24]. The gene discussed is BDNF; the disease is major depressive disorder.