Current evidence on the association of tongue strength with cognitive decline in older adults and the known risk factors of frailty, sarcopenia and nutritional health: a scoping review protocol

Introduction: Evidence suggests that the pathology underlying cognitive decline leading to dementia begins 15–20 years before cognitive symptoms emerge. Thus, identifying biomarkers in this preclinical phase is critically important. Age-related decrease in muscle mass and strength, a known risk factor for sarcopenia, frailty and cognitive decline, also affects the tongue. This paper describes an a priori protocol by a multidisciplinary team to address the following questions relating to adults ≥50 years of age: (1) What is the current evidence on the association of tongue strength with cognitive decline? (2) How does tongue strength associate with frailty and sarcopenia? (3) What is the association of tongue strength with nutritional health?

Methods and analysis: Search terms will be identified then multiple electronic databases (PubMed, PsycINFO (Ovid), Scopus, Embase (Ovid), CINAHL and Web of Science) searched systematically for peer-reviewed articles published in English that address the following inclusion criteria: (1) human studies, (2) participants ≥50 years of age and (3) studies with tongue pressure values measured in relation to at least one of the following: frailty, sarcopenia, nutritional health, cognitive function and dementia (Alzheimer’s, vascular, frontotemporal and Lewy body). Grey literature also will be searched to identify additional studies, clinical trials and policy papers appropriate for inclusion. The search will be from database inception. After removing duplicates, two research team members will independently screen abstracts and identify articles for full-text review. The team will use a data charting tool for data extraction. Data will be analysed quantitatively and qualitatively.