Can Gut Flora Changes Be New Biomarkers for Depression?

The document from 2017 explores the potential of gut flora changes as biomarkers for major depressive disorder (MDD). It reviews the gut-brain axis and how gut microbes may influence psychological disorders like depression. The paper discusses current and emerging biomarkers for MDD, including neuroactive steroids, plasma, and serum protein biomarkers, inflammatory markers, and the kynurenine pathway. It cites studies that have found altered levels of these biomarkers in MDD patients and suggests that gut flora changes, such as specific proportions of Prevotella and Klebsiella, could indicate depressive states. The document emphasizes the need for further research to understand the relationship between gut flora and depression better and to develop new diagnostic and treatment strategies. However, it does not provide conclusive evidence that gut flora changes are currently used as biomarkers for depression.