Age-driven dysbiosis: gut microbiota in the pathogenesis and treatment of aging disorders

Aging, a complex physiological and molecular process, has undergone significant changes, of which gut microbiome composition has surfaced as an important key in the maintenance of neurological health. Recent studies have revealed the significant impact of age-related gut dysbiosis in the induction of neuroinflammation, metabolic syndrome, disruptions in gut-brain axis, and age-related neurological decline. Although significant studies have revealed the impact of the microbiome-gut-brain axis in individual neurological diseases, an aging-focused holistic synthesis has not yet been adequately developed. This review provides a critical assessment of the involvement of age-related dysbiosis of gut microbiota in the development and progression of neurological disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and cognitive aging of the elderly, and to focus on age-related microbial patterns and mechanisms of dysbiosis related to neurological aging, including inflammation and immune system dysregulation, metabolic changes, oxidative stress, barrier dysfunction, and gut-brain communication through enteroendocrine, enteric neural, and vagal mechanisms, and to emphasize disease-specific and common microbial patterns of dysbiosis and beneficial and harmful microbial roles in aging diseases. This review assesses some of the latest promising therapies aimed at the microbiota, such as probiotics, prebiotics, dietary therapies, fecal microbiota transplantation, as well as pharmacological therapies, and critically discusses their limitations in terms of interindividual variability and their generalisation and applicability. Focusing on mechanistic, comparative, and translation aspects, this review offers a comprehensive approach to neurological aging due to gut microbiota and identifies gaps for future precision microbiome-based interventions.