BDNF and major depressive disorder: Consistent with this, BDNF has emerged as a critical mediator for the efficacy of various antidepressants by reversing the reduced neuroplasticity in the PFC and hippocampus in depression; the same improvement in neuroplasticity also occurs after chronic antidepressant treatment (Castrén and Rantamäki, 2010; Duman and Monteggia, 2006).