Gut Microbiota and Cognitive Function: A Review of Neurobiological Mechanisms of the Gut–Brain Axis
TL;DR
Current evidence supports the gut microbiota as a significant cognitive modulator via the microbiota–gut–brain axis, and larger randomized controlled trials and standardized protocols are necessary to confirm long-term efficacy and clinical utility.
Abstract
Introduction: The gut microbiota is a key regulator of the gut–brain axis, essential for neurological, immune, and metabolic balance. Emerging evidence links microbial dysbiosis to cognitive impairments—including memory, attention, learning, and executive function—via neuroinflammation, metabolic signals, and neurotransmitter pathways. Method: This review systematically evaluates current evidence on the gut microbiota–cognition relationship, emphasizing neurobiological mechanisms. A literature search in PubMed, Scopus, Web of Science, and Google Scholar (up to 2026) using relevant keywords identified animal studies, human observational research, and clinical trials, which were qualitatively synthesized. Results: Findings show that gut microbiota affects cognition through neural, immune, metabolic, and epigenetic networks. Animal studies consistently report that dysbiosis reduces hippocampal neurogenesis, synaptic plasticity, and BDNF expression, while increasing neuroinflammation and impairing learning/memory. Human studies suggest that microbiota-targeted interventions—probiotics, prebiotics, synbiotics, and diet—may enhance cognitive performance by boosting short-chain fatty acids, modulating inflammation, regulating neurotransmitters, improving gut barrier function, and strengthening brain-region connectivity for memory and attention. However, heterogeneous study designs, interventions, and populations lead to inconsistent outcomes, underscoring the need for more rigorous trials. Conclusion: Current evidence supports the gut microbiota as a significant cognitive modulator via the microbiota–gut–brain axis. Dysbiosis may drive cognitive decline through neuroinflammation and altered neural signaling. While microbiota-based therapies show promise for preventing or alleviating cognitive impairment, larger randomized controlled trials and standardized protocols are necessary to confirm long-term efficacy and clinical utility. Deeper molecular insights into gut–brain communication are crucial for developing personalized therapeutic strategies for neurological and cognitive disorders.