Altered gut microbial diversity, composition, and metabolomic potential in patients with major depressive disorder and recent suicide attempt

This study investigates the role of the gut microbiome in suicidal behavior among individuals with major depressive disorder (MDD). Fecal samples from 50 hospitalized patients with MDD, including 35 with recent suicide attempts (60 % female) and 15 without a history of suicide (73 % female), were analyzed using 16S rRNA and shotgun sequencing to assess microbiome diversity and metabolic potential. Results revealed that suicide attempters exhibited significantly greater microbial richness and distinct beta-diversity patterns. Notably, they had higher levels of Fenollaria timonensis and lower levels of Corynebacterium aurimucosum. Additionally, 25 metabolic pathways differed between groups, with several linked to energy metabolism and amino acid processing—processes previously associated with MDD and suicidal behavior. These findings suggest that microbiome composition may influence suicide risk through gut-brain axis-mediated pathways, although due to the exploratory nature of this study further investigation is needed to validate our findings. Given the microbiome's modifiability, future research should explore microbial-targeted interventions as a potential strategy for suicide prevention in individuals with MDD.