Bipolar disorder and the gut microbiome: A systematic review

Area of Science:

• Neuroscience
• Microbiology
• Psychiatry

Background:

• The gut microbiome plays a crucial role in host metabolism and interacts with the central nervous system via the gut-brain axis.
• Short-chain fatty acids, such as butyrate, are microbial metabolites that can influence host physiology.
• Understanding the gut microbiota in bipolar disorder (BD) is essential for identifying potential biomarkers and therapeutic targets.

Purpose of the Study:

• To review and synthesize findings on gut microbiota alterations in individuals with bipolar disorder (BD).
• To explore the potential link between gut dysbiosis, butyrate production, and inflammation in BD pathophysiology.

Main Methods:

• A systematic literature search was conducted on PubMed using keywords related to bipolar disorder and microbiome/microbiota.
• Inclusion criteria focused on studies comparing gut microbiota in distinct BD and healthy control (HC) groups.
• Thirteen relevant articles published in English were identified and analyzed.

Main Results:

• Lower alpha-diversity of gut microbiota was observed in BD patients compared to HC in most studies.
• Reduced abundance of Faecalibacterium prausnitzii (a butyrate producer) was a common finding in BD, although one study reported an increase.
• Alterations in Bacteroides species were also noted, with some studies showing increased abundance in BD and others showing decreased abundance.

Conclusions:

• Gut dysbiosis, characterized by low alpha-diversity and altered abundance of Faecalibacterium and Bacteroides, may be a feature of BD.
• Reduced butyrate production and associated inflammation could contribute to the pathophysiology of bipolar disorder.
• Further research with larger sample sizes is needed to confirm these findings and explore therapeutic implications.