SLC6A3 and schizophrenia: On the other hand, associations between striatal DAT and plasma levels of metabolites involved in the methionine cycle have been reported in schizophrenia (Yang et al., 2022a) and metabolic syndrome (Hartstra et al., 2020), implicating the potential roles of methylation reactions or oxidative stress in DAT expressions (Kim & Andreazza, 2012; Wiers et al., 2018; Yang et al., 2022a).