The Tale of Depression and Inflammation Unraveled: On Depression Measurement Levels and Next Steps

Abstract

The evidence for a link between the immune-inflammatory system and depression is highly robust. Strong pillars in the evidence include, among others, the observations that interferon treatment in a large proportion of those treated leads to clinically relevant depressive symptoms, and the large number of case-control studies summarized in meta-analyses pointing to elevated peripheral inflammatory markers in persons with a major depressive disorder versus those without. However, meta-analyses of inflammatory markers typically show small to moderate effect sizes and large heterogeneity.