A gut bacteria signature associated with depressive symptoms is reported in two papers published in Nature Communications. The findings identify specific gut bacteria that are involved in the synthesis of key chemical messengers linked with depression, and associated differences across ethnicities.
Despite being a leading cause of mortality and economic disparity, depression remains poorly understood as the causes are unclear, and treatment options are limited. The gut microbiome is thought to play a role in depressive disorders, but the underlying biological mechanisms are understudied. Moreover, both the microbiome and depressive symptom levels are known to vary substantially across ethnic groups. Therefore, any future interventions for depression targeting the microbiome require an understanding of microbiome-depression associations across ethnicities.
Jos Bosch, Anja Lok, Susanne de Rooij and colleagues studied a group of 3,211 individuals from the HELIUS study microbiome cohort, consisting of six ethnic groups living in urban Amsterdam, including Dutch, South-Asian Surinamese, African Surinamese, Ghanaian, Turkish and Moroccan. Linking microbiota data with demographic, behavioural, and depression data, the authors identified a microbial signature predictive of depressive symptoms that was largely invariant across the ethnic groups studied.
In a co-published paper, Najaf Amin, Robert Kraaij, Djawad Radjabzadeh and colleagues, compared the gut microbiota characteristics of 1,054 participants from a separate cohort in the Netherlands, named the Rotterdam Cohort, and found 13 microbial taxa associated with depressive symptoms, such as Eggerthella, Subdoligranulum and Coprococcus. These findings were then replicated in the HELIUS study cohort. The authors found that these bacteria are involved in the synthesis of known chemical messengers associated with depression, such as glutamate, butyrate, serotonin and gamma amino butyric acid (GABA). The faecal microbiome was studied as a proxy of the gut microbiome in both studies.
Although the clinical impacts of these findings need to be confirmed experimentally, together the two studies further reinforce the link between gut microbiome composition and depression, and suggest it may be a useful target for future therapies.
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