BDNF and major depressive disorder: Taking into account the above arguments, our goals were: 1) to compare peripheral levels of IGF-1 in MDD patients and HC; 2) to elucidate possible associations between changes in IGF-1 expression and crucial characteristics of the current DE and MDD course; 3) to evaluate the dynamics of the neurotrophin levels after 8 weeks of treatment with vortioxetine.