Inflammatory Biomarker and Response to Antidepressant in Major Depressive Disorder: a Systematic Review and Meta-Analysis

Inadequate response to antidepressant treatment, in a significant proportion of patients diagnosed with Major Depressive Disorder, contributes to the large burden of disability associated with the disease; thus, predicting treatment response is one of the most important challenge for clinicians who deal with depressed patients. The cytokine hypothesis of depression suggests that altered pheripheral cytokine levels are involved in the pathophysiology of depressive disorder and in modulating response to treatment. Present meta-analysis aimed to investigate the association between cytokine levels at baseline and response to antidepressant therapies. Authors performed a systematic search of PubMed and Embase databases for studies published between 2010 and January 2021: of 3345 identified records, 31 studies met the inclusion criteria for the qualitative synthesis, whereas 19 studies were eligible for quantitative analysis. Patients who failed to respond to antidepressant had aberrant inflammatory process, namely higher baseline levels of C-Reactive Protein and Interleukine-8, which is associated with treatment outcome in Major Depressive Disorder. Despite these promising results, further investigations are needed in order to replicate the data and to examine the potential role of inflammatory marker as a novel predictive tool for pharmacological treatment of depressive disorder.