Clinically Measuring Orofacial Somatosensation in a Cohort of Healthy Aging Adults

PURPOSE

Humans experience the world through sensations of touch, taste, smell, vision, and audition. Alterations in sensory acuity occur across the adult life span in all types of sensation. The purpose of this study was to describe possible differences in lip and tongue somatosensation (sense of pressure) for healthy older adults using clinically available measurement tools as compared with previously published data using the same protocol.

METHOD

A total of 33 healthy adults (ages 60-93 years; M = 70.5 years; 19 women) completed bilateral assessment of lip and tongue pressure detection and discrimination using two-point discrimination discs and Von Frey hair monofilaments. Participants reported basic health information and completed a pure-tone hearing threshold assessment within the same session.

RESULTS

Descriptive results are presented for individual data points from healthy aging adults. Group data are compared with previously published data from a cohort of healthy young participants. Although there were no statistically significant differences between the two healthy groups, variations in standard deviations in older adults were observed.

CONCLUSIONS

Two-point discrimination and tactile detection and discrimination using Von Frey hair monofilaments can be used to assess labial and lingual pressure detection and discrimination in healthy aging adults. While not reaching statistical significance, on average, older adults demonstrated increased threshold estimates compared with younger adults with increases in standard deviations up to 11.5 times larger than the younger cohort. Subtle differences in somatosensation across the ages may be important for future comparisons with clinical populations across the life span. These assessment techniques can be used with an aging population to complete objective orofacial somatosensory testing.

Somatosensory function in old age

Sensory decline is viewed as an inevitable consequence of the ageing process. However, reports of declines have not been a consistent finding across the sensory systems. Reports from psychophysical studies indicate that the most common declines with ageing are in vision and audition and, to a lesser degree, olfaction and gustation. Findings for the somatosensory system (mechanoreception, warming and cooling thermoreception and pain) are less conclusive. Factors that contribute to individual differences in sensory ratings beyond chronological ageing include stimulus factors including stimulus type and body location, response measures and instructions, systemic disease that may affect the peripheral or central nervous system and environmental factors that may affect the skin integrity.

The relationship between labial vibrotactile detection and pure-tone hearing thresholds in healthy, ageing adults

PURPOSE

Orofacial anatomy is unique from other body systems in that oral musculature inserts directly into the underlying cutaneous skin, allowing for tight temporal synchronicity between somatosensory and auditory performance feedback to maintain correct orofacial behaviours across the lifespan. Unfortunately, little is currently known regarding the changes in orofacial sensory capacities associated with ageing and how these somatosensory and auditory changes may impact feedback during functional behaviours such as speech or swallowing. The purpose of this descriptive study was to begin assessing the relationship between the auditory and labial somatosensory system in healthy ageing adults.

METHOD

Pure-tone hearing thresholds were determined for 500, 1000, 2000 and 4000 Hz. Using a 2-alternative forced choice paradigm, 60 adults (19-84 years) completed vibrotactile detection thresholds (VDT) at the 5 and 10 Hz test frequencies.

RESULT

A significant difference for age by group was identified at the 5 Hz test frequency. Spearman Correlations identified a significant correlation between age and pure tone hearing thresholds and the 5 Hz test frequency threshold.

CONCLUSION

A relationship between pure tone hearing thresholds and labial somatosensory was identified. Future studies will begin the processing of modelling the complex multivariate sensorimotor relationship in healthy individuals before moving to a disordered population.

Controversies in fat perception

Nutritional fat is one of the most controversial topics in nutritional research, particularly against the background of obesity. Studies investigating fat taste perception have revealed several associations with sensory, genetic, and personal factors (e.g. BMI). However, neuronal activation patterns, which are known to be highly sensitive to different tastes as well as to BMI differences, have not yet been included in the scheme of fat taste perception. We will therefore provide a comprehensive survey of the sensory, genetic, and personal factors associated with fat taste perception and highlight the benefits of applying neuroimaging research. We will also give a critical overview of studies investigating sensory fat perception and the challenges resulting from multifaceted methodological approaches. In conclusion, we will discuss a multifactorial approach to fat perception to gain a better understanding of the underlying mechanisms that cause varying fat sensitivity which could be responsible for overeating. Such knowledge might be beneficial in new treatment strategies for obesity and overweight.