As mentioned earlier, a one-way analysis of variance with Welch’s correction and Games–Howell post hoc tests showed that serum cortisol levels were significantly higher in patients with schizophrenia than in patients with MDD (p < 0.01; Fig. 1A) and that there was no significant difference in serum IGF-1 levels between patients with MDD and schizophrenia (p = 1.0; Fig. 1B). This evidence concerns the gene IGF1 and schizophrenia.