Effects of aging and sarcopenia on tongue pressure and jaw-opening force.

AIM: Aging and sarcopenia reduce not only body strength, but also the strength of swallowing muscles. We examined how aging and sarcopenia affect tongue pressure and jaw-opening force. METHODS: A total of 97 older adults (97 men, mean age 78.5 ± 6.6 years; 100 women, mean age 77.8 ± 6.2 years) were enrolled. Classification of sarcopenia was based on the Criteria of Asian Working Group for Sarcopenia. To investigate which variable between aging and sarcopenia was a significant independent variable on tongue pressure and jaw-opening force, multivariate linear regression analysis was carried out. RESULTS: The mean tongue pressure was 26.3 ± 7.8 kPa in men and 24.6 ± 7.2 kPa in women. The mean jaw-opening force was 6.3 ± 1.6 kg in men and 5.2 ± 1.3 kg in women. Tongue pressure in men, aging and sarcopenia were significant independent variables, whereas only sarcopenia was a significant independent variable in women. Jaw-opening force in men and sarcopenia were significant independent variables, whereas neither aging nor sarcopenia were significant independent variables in women. CONCLUSIONS: We found different characteristics in the effects of aging and sarcopenia based on site and sex. We suggested that aging decreased tongue pressure more than jaw-opening force, and affected men more than women. Sarcopenia affected tongue pressure and jaw-opening force, with the exception of jaw-opening force in women. Considering these characteristics is useful to predict the decline of swallowing function, and provide appropriate interventions preventing dysphagia. Geriatr Gerontol Int 2017; 17: 295-301.

Facial vibrotactile stimulation activates the parasympathetic nervous system: study of salivary secretion, heart rate, pupillary reflex, and functional near-infrared spectroscopy activity.

We previously found that the greatest salivation response in healthy human subjects is produced by facial vibrotactile stimulation of 89 Hz frequency with 1.9 µ m amplitude (89 Hz-S), as reported by Hiraba et al. (2012, 20011, and 2008). We assessed relationships between the blood flow to brain via functional near-infrared spectroscopy (fNIRS) in the frontal cortex and autonomic parameters. We used the heart rate (HRV: heart rate variability analysis in RR intervals), pupil reflex, and salivation as parameters, but the interrelation between each parameter and fNIRS measures remains unknown. We were to investigate the relationship in response to established paradigms using simultaneously each parameter-fNIRS recording in healthy human subjects. Analysis of fNIRS was examined by a comparison of various values between before and after various stimuli (89 Hz-S, 114 Hz-S, listen to classic music, and "Ahh" vocalization). We confirmed that vibrotactile stimulation (89 Hz) of the parotid glands led to the greatest salivation, greatest increase in heart rate variability, and the most constricted pupils. Furthermore, there were almost no detectable differences between fNIRS during 89 Hz-S and fNIRS during listening to classical music of fans. Thus, vibrotactile stimulation of 89 Hz seems to evoke parasympathetic activity.