Tongue strength and cognitive decline in older adults: A scoping review

There is a need to identify non-invasive, accessible biomarkers of cognitive decline and dementia risk. Frailty, sarcopenia and poor nutritional health are known to increase the risk of cognitive impairment and decreased tongue strength is a key component of all these. It remains unclear, though, if tongue strength holds potential as a non-invasive biomarker of cognitive decline. This scoping review mapped evidence from adults ≥50 years of age to document associations between tongue strength and cognitive decline, as well as the known risk factors of frailty, sarcopenia, and poor nutritional health.

The JBI scoping review methodology and the PRISMA-ScR guided the review process. Six databases were searched: PubMed, PsycINFO (Ovid), Scopus, Embase (Ovid), CINAHL, and Web of Science.

Of 3409 records identified, 59 studies with 27,073 participants met eligibility criteria; these were published between 2011 and 2024, with 45 studies cross-sectional and 14 longitudinal, including two RCTs. Although measurement methods varied across the studies, there was evidence that decreased tongue strength in older adults was associated with cognitive decline (including Mild Cognitive Impairment and dementia), physical frailty, sarcopenia, and poorer nutritional health.

Tongue strength holds promise as a new biomarker of cognitive decline and dementia risk. Effective interventions exist to strengthen the tongue. This further supports the importance of measuring tongue strength to optimise older adults' health and cognitive function. Further culturally diverse, longitudinal studies are needed to validate the observed associations and establish specific tongue strength cutoff values to determine stages of cognitive decline.