“…Several lines of evidence suggest that ketamine use influence cytokines, growth factors, and neurotrophic factors productions (Becker, Grecksch, Schwegler, & Roskoden, ; Chen, Chang, Lin, Ueng, & Chen, ; Fan, Luo, et al, ; Fan, Zhang, et al, ). Previously, we reported that serum levels of BDNF and nerve growth factor in chronic ketamine users were significantly lower than those in healthy subjects (Ke et al, ).…”