Although, there is no concensus regarding the best way to monitor increased BBB permeability in patients with schizophrenia, several novel candidates including matrix metalloproteinase-9(MMP-9), ubiquitin carboxy-terminal hydrolase-L1(UCHL-L1), neurofilaments, brain derived neurotropic factor (BDNF), miRNA in addition to S100B and glial fibrillary acidic protein (GFAP) are available for future studies, and preferably aggregated and applied in panels of several biomarkers (86). Here, MMP9 is linked to schizophrenia.