Age-Specific Clinical and Brain Features of Masticatory and Swallowing Performance

Mastication and swallowing are the fundamental processes for food intake and the primary functions of living. The clinical and neurological features associated with individual differences in masticatory performance and swallowing performance have remained unexplored.

The study focuses on the age-specific association between masticatory/swallowing performance and oral/systemic/nutritional factors and their association with functional brain connectivity.

One-hundred and eighteen healthy adults (48 older age, 27 middle-aged and 43 younger age) were recruited for food-mixing and repetitive saliva swallowing tests, respectively, indexed for masticatory and swallowing performance, as well as oral, systemic and nutritional factors, including mid-upper arm and calf circumferences. Structural and resting-state (rs) functional magnetic resonance imaging was acquired. Seed-based connectivity analyses were conducted to investigate the association between swallowing performance and rs-functional connectivity (rs-FC) of the sensorimotor network.

(a) In contrast to mastication, individual swallowing performance was not associated with oral or systemic factors. (b) In older adults, higher mid-upper arm and calf circumferences were associated with both higher masticatory and swallowing performance (a statistically significant interaction, p = 0.018). (c) In older adults, higher swallowing performance was associated with stronger rs-FC between the cerebellum and basal ganglia (p = 0.008, corrected for small volume), whilst higher masticatory performance was associated with stronger rs-FC between the cerebellum and primary sensorimotor cortices (p = 0.045, corrected for small volume).

Our findings reveal age-specific associations between swallowing, mastication, nutritional factors and brain functional connectivity. The findings highlight the association between the brain and individual differences in masticatory and swallowing performance.