BDNF and schizophrenia: BDNF is one of the important neurotropic factors that plays a role in the neurodevelopmental model and schizophrenia pathophysiology [27].Although the source of BDNF in the serum has not yet been clearly discovered because blood can pass through the brain barrier in both directions [28], the serum BDNF gives us have an idea about cortical BDNF [29].