BDNF and schizophrenia: It has been revealed that serum BDNF levels in the patients treated with clozapine are higher than those treated with risperidone or typical antipsychotics (Dong et al., 2021), However, it has been shown that serum levels of BDNF of patients with schizophrenia do not raise after antipsychotic treatment (Pirildar et al., 2004).