Muscle aging such as sarcopenia adversely affects motor activities. However, few studies have elucidated the aging physiological mechanism of tongue concerted with the changes muscle composition. The present study aimed to examine the tongue composition changes to detect the effect of tongue fat mass on tongue pressure and swallowing function with aging. Twenty community-dwelling elderly without head and neck cancer, stroke, or neuromuscular disease and 20 healthy young were included. Tongue volume, tongue fat mass, tongue lean muscle mass, and tongue fat percentage were evaluated with 3D magnetic resonance imaging (MRI) and Dixon MRI. Tongue pressure was also measured. Swallowing function among elderly individuals was assessed via videofluorography, which was evaluated using the penetration-aspiration scale (PAS) and normalized residue ratio scale (NRRS). Tongue fat mass and tongue fat percentage significantly increased with aging. The tongue fat percentage of elderly participants was 20%, which was two times greater than that of young participants. No significant difference was observed in tongue volume and tongue lean muscle mass. A significantly negative correlation was observed between tongue fat mass and tongue fat percentage as well as tongue pressure. Conversely, tongue volume was not significantly correlated with tongue pressure. Tongue muscle composition exhibited no effect in the PAS and NRRS. Increase of fat mass is a major change in tongue composition with aging, which is associated with low tongue pressure. Thus, attention must be paid not only to tongue quantity but also to the quality of tongue muscles.
Keywords: Aging; Deglutition; Deglutition disorders; Dixon MRI; Intramuscular fatty infiltration; Tongue pressure.