A positive correlation was found between IGF-1 levels and the diagnosis of MDD (r = 0.50, p < 0.01), the number (r = 0.43, p < 0.01) and duration of depressive episodes (r= 0.37, p < 0.01) and the severity of symptoms on the MADRS (r = 0.46, p < 0.01), and a negative correlation was demonstrated between IGF-1 and the results of cognitive function tests [41]. The gene discussed is IGF1; the disease is major depressive disorder.