Silent Intruders: The Gut Virome in Brain Aging and Cognitive Decline

Recent advances in next-generation sequencing have revealed that the virome-the set of viruses residing in the gastrointestinal tract-is a fundamental yet still underexplored component of the human intestinal ecosystem. Despite the prevalence of research focused on bacterial alterations, recent findings suggest a significant role for viral elements within the intestinal microbiota, namely latent viruses, bacteriophages and eukaryotic viruses, in influencing brain health. Alterations in the gut virome may, in particular, contribute to the processes underlying brain aging, cognitive decline, and neurodegenerative diseases such as Alzheimer's, Parkinson's, and multiple sclerosis (MS). This review highlights the potential of intestinal viruses to modulate gut barrier integrity, systemic immune response and neuroimmune inflammation. Such interactions could promote conditions of chronic neuroinflammation, alterations in synaptic plasticity, and neuronal vulnerability. A more comprehensive understanding of the role of the gut virome could potentially result in novel approaches to the early detection and treatment of neurocognitive disorders in adults and older individuals.