Microbes and ageing beyond the gut: the oral microbiome and frailty, sarcopenia and neurocognitive disorders in the elderly-a scoping review protocol

Introduction Population ageing is a global phenomenon that has resulted in an increase in the number of patients with chronic diseases and geriatric syndromes. Frailty, sarcopenia and neurocognitive disorders are among the most prevalent conditions affecting older adults and have a direct effect on their quality of life, and can impact the burden and budgets of health systems. Recently, the oral microbiome has gained attention as it may be a factor that potentially influences the onset and progression of these syndromes. However, this is still a new line of research that has not been deeply explored. This scoping review protocol aims to explore how the oral microbiome may be associated with the onset of prevalent geriatric syndromes, frailty, sarcopenia and neurocognitive disorders, providing a picture of the current evidence and potential gaps for future research. Methods and analysis The scoping review will follow the Johanna Briggs Institute (JBI) methodology and will be reported accordit to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews guidelines (PRISMA-ScR). Searches will be conducted in Medline, Embase, Cochrane Central, CINAHL, LILACS and Epistemonikos from inception to December 2025. Independent reviewers will perform the study selection and data extraction. A descriptive analysis of information will be conducted, highlighting oral microorganisms associated with these syndromes and emerging trends in the evidence. Original research studies in any language will be included. We will include randomised controlled trials, cohort studies, case–control studies and other relevant designs if they investigate the oral microbiome and its relation to geriatric syndromes in adults aged 65 or older, regardless of geographic location or setting. Ethics and dissemination Ethics approval is not required.