Associations of plasma interleukin-6 with plasma and cerebrospinal fluid monoamine biosynthetic pathway metabolites in treatment-resistant depression

The findings of the current study extend current evidence that plasma IL-6 levels are elevated in TR-MDD, after adjusting for body mass index. Additionally, plasma IL-6 and serotonin regulation may vary between healthy and TR-MDD populations. Lastly, our study finds no association between plasma IL-6 and CSF monoamine pathway metabolites, suggesting that further research is needed to elucidate the association of IL-6 and depression.