This project contains the protocol, manuscript, and supplementary materials for a systematic review conducted according to PRISMA 2020 guidelines. The review synthesizes evidence from 89 studies (2014–March 2025) examining gut microbiota composition in adults with major depressive disorder (MDD) compared to healthy controls. Primary objectives: (1) characterize gut microbiome alterations in MDD; (2) evaluate biological mechanisms (SCFAs, inflammation, tryptophan-kynurenine pathway, HPA axis); (3) assess translational potential for diagnostic biomarkers and psychobiotic interventions. The study protocol was developed a priori and registered prospectively to ensure methodological transparency and minimize selective reporting.
Cicoli et al. (Thu,) studied this question.