GSTM1 and major depressive disorder: For the first time, this study used fNIRS to investigate differences in oxy-Hb activation among the groups with healthy-low resilience, healthy-high resilience, depression-low resilience and depression-high resilience, and further explored the mediating role of resilience levels in the degree of depression in oxy-Hb activation, to reveal how resilience might protect individuals from depressive symptoms and what neural mechanisms could underlie this “protective” effect.