The Potential Role of Biotics on Cognitive Impairment by Modulating Gut Microbiota: An Updated Review of Effects and Mechanisms

Cognitive impairment is a serious public health problem, with severe decline progressing to dementia. Early prevention and long-term management are therefore crucial for cognitive impairment, yet current treatments remain limited. Recent evidence highlights the gut microbiota and the gut-brain axis as vital regulators of cognitive impairment. In this context, various “biotics” including probiotics, prebiotics, synbiotics and postbiotics have shown potential impact on cognitive impairment by modulating the gut microbiota. This narrative review synthesizes recent literature to summarize the effects and mechanism of biotics on cognitive impairment from preclinical and clinical evidence. Findings indicate that biotics improve cognitive impairment by modulating gut microbiota dysbiosis, restoring intestinal and blood-brain barrier integrity, and attenuating neuroinflammation and oxidative stress. Furthermore, biotics appear to enhance neurotransmitter balance, neurotrophic factor expression and synaptic plasticity. Although clinical trials exhibit heterogeneity and are often influenced by biotics’ formulation, dosage, duration and host factors, the evidence generally suggests meaningful cognitive benefits. In conclusion, this review elucidates biotics’ potential benefits on cognitive impairment with multifaceted mechanisms, highlighting their promise as microbiota-targeted interventions and informing future research directions for optimized strategies.