In another study by Schaefer M et al depression was reported up to 70% in HCV patients in the interferon era related to interferon may be due to alteration in monoamine metabolism, high apoptosis rate, altered function of hypothalamic pituitary axis and reduced level of brain derived neurotropic factor (BDNF).17 However, that higher rate could be due to a difference in the treatment medication. This evidence concerns the gene BDNF and major depressive disorder.