Gut Microbiota-Brain Axis and Related Biomarkers

The relationship between dysbiosis and the pathophysiology of schizophrenia spectrum disorders (SSD) is an increasingly explored and researched area within psychiatry and neurology. While the precise mechanisms remain incompletely understood, evidence suggests that the gut microbiota may influence brain function through the gut-brain axis. This chapter provides a comprehensive review of studies conducted over the past 12 years (2011–2023) with the aim of investigating the biomarker potential of altered microbiota and associated metabolites in constructing diagnostic models for SSD, assessed through the receiver operating characteristic (ROC) analysis. Aggregate findings across these studies identified a total of 30 metabolites associated with the dysregulation of intestinal flora, constituting a potential disease signature as confirmed by enrichment analysis. In addition, significant alterations were observed in 7 phyla, 34 families, and 62 genera of bacteria. Bacillota emerged as the most prevalent phylum in all studies (100%), followed by Actinomycetota (91%) and Pseudomonadota (82%). Among families, Lachnospiraceae (80%), known for the production of anti-inflammatory molecules, stood out, and its most frequent genera, including Coprococcus, Dorea, Roseburia, and Blautia, exhibited reduced abundance in the feces of individuals with SSD. Models utilizing either metabolites or bacteria consistently demonstrated excellent performance (AUCs ranging from 80% to 99%).