Gut microbiota and major depressive disorder: A bidirectional Mendelian randomization

Area of Science:

• Microbiome research
• Psychiatric genetics
• Human health

Background:

• Observational studies suggest a link between gut microbiota and depression.
• The causal relationship between gut microbiota and major depressive disorders (MDD) remains unclear.

Purpose of the Study:

• To investigate the bidirectional causal relationship between gut microbiota composition and MDD.
• To explore the potential of gut microbiota in reducing MDD risk.

Main Methods:

• A two-sample Mendelian randomization (MR) study was conducted.
• Genome-wide association study (GWAS) data for gut microbiota (n=18,340) and MDD (n=480,359) were utilized.
• Inverse-variance weighted meta-analysis and sensitivity analyses were performed.

Main Results:

• The Actinobacteria class and Bifidobacterium genus showed protective causal effects against MDD.
• The Ruminococcus genus also demonstrated a protective effect on MDD.
• Streptococcaceae family and genus showed a potential anti-protective effect, though not consistently supported by all analyses. No significant effect of MDD on gut microbiota was found.

Conclusions:

• Specific gut bacteria, including Actinobacteria and Bifidobacterium, may play a protective role in MDD.
• Further research is warranted to translate these findings into clinical practice for MDD prevention or treatment.