BDNF and major depressive disorder: Animal experiments have demonstrated that the ethanol, aqueous, and ethyl acetate extracts of Rhizoma Gastrodiae, GAS, 4‐hydroxybenzyl alcohol, and vanillin can all improve depression in mice prominently,11 which exert antidepressant effects primarily through multiple pathways like monoamine neurotransmitter, antioxidant, anti‐inflammatory, BDNF, and HPA axis regulations.12, 13