BDNF and schizophrenia: The association between serum BDNF levels and antipsychotics remains poorly understood and relevant studies have given contradictory results: while some studies have indicated the different role of some SGAs (clozapine, quetiapine or risperidone) in serum BDNF levels compared to FGAs [8]–[11], [15], [53]–[56], some others failed to find any differences in serum BDNF levels following treatment with antipsychotics [16], [57], or even any differences in serum BDNF levels between patients with schizophrenia and healthy controls [58], [59].