Indeed, inflammatory status has been shown to predict responsiveness to electroconvulsive therapy and ketamine treatment [189,190,191], and, while the treatment of TRD patients with a TNF neutralizing antibody, infliximab, showed no overall differences between groups in terms of symptom improvement, post-hoc analysis demonstrated a significant interaction between the treatment and baseline level of inflammation (as measured by CRP) [192]. Here, CRP is linked to treatment resistant depression.