There was a significant difference in IGF-1 levels between the two groups, and serum IGF-1 levels were significantly increased in patients with first-episode and drug-naïve depression (MDD:149.81 ± 34.35 ng/ml, control:128.23 ± 25.83 ng/ml, p<0.05). The gene discussed is IGF1; the disease is major depressive disorder.