When comparing the data between schizophrenia and depression, oxy-Hb (p = 0.011, mean difference = −10.88, effect size = 1.242, CI of difference = −19.56 to −2.192), total-Hb (p = 0.019, mean difference = −14.23, effect size = 1.161, CI of difference = −26.41 to −2.057), oxy-Hb/blood-Hb (p = 0.003, mean difference = −0.8110, effect size = 1.560, CI of difference = −1.371 to −0.2510), and total-Hb/blood-Hb (p = 0.008, mean difference = −1.070, effect size = 1.396, CI of difference = −1.890 to −0.2505) in schizophrenia were significantly lower than the depression data. This evidence concerns the gene GSTM1 and depressive symptom measurement.