GSTM1 and depressive symptom measurement: The 53‐channel functional near‐infrared spectroscopy (fNIRS) was used to monitor the concentration of oxy‐hemoglobin (Oxy‐Hb) in the brain, whereas the participants performed the verbal fluency task, and the degree of depression was scored using the 17‐item Hamilton Rating Scale for Depression (HAMD‐17).