Jiang, R.-S. | bioRxiv Science

bioRxiv2019

Influence of age and gender on taste function of healthy subjects

ObjectivesTo determine the influences of age and gender on the taste functions of healthy Taiwanese. MethodsWe evaluated taste functions of healthy Taiwanese using the whole mouth suprathreshold taste test, along with the taste quad test. In the whole-mouth test, we applied in a counterbalanced order sweet, sour, salty, and bitter solutions, each at 5 different suprathreshold concentrations to subjects, who were instructed to sip and swish in mouth twice. Each subject had to indicate the taste quality, and to rate the intensity and unpleasantness/pleasantness of each taste of the solutions. In the quad test, the 4 quadrants of the tongue surface were tested by dripping one concentration of sweet, sour, salty, or bitter solutions for 6 times. Subjects then indicated the taste quality, and rated the intensity of the solution. ResultsSubjects were divided into groups based on their gender and age: 20-39 years, 40-59 years, or [≥] 60 years. We found that in the whole mouth taste test, the total correct identification score dropped with age. But identifying sweet and salty qualities was not affected by age. No differences were found between male and female, except women scored better than men for sweet quality in the age group of 40-59 years. The total correct identification score of the taste quad test also decreased with an increased age of the taste quad test, without gender differences. ConclusionBoth age and gender affected the taste functions in healthy Taiwanese to some extent, and differences were dependent on age, tongue region, and taste quality.

physiology↗

bioRxiv2017

SMELL-S and SMELL-R: olfactory tests not influenced by odor-specific insensitivity or prior olfactory experience

Smell dysfunction is a common and underdiagnosed medical condition that can have serious consequences. It is also an early biomarker of Alzheimers disease that precedes detectable memory loss. Clinical tests that evaluate the sense of smell face two major challenges. First, human sensitivity to individual odorants varies significantly, leading to potential misdiagnosis of people with an otherwise normal sense of smell but insensitivity to the test odorant. Second, prior familiarity with odor stimuli can bias smell test performance. We have developed new non- semantic tests for olfactory sensitivity (SMELL-S) and olfactory resolution (SMELL-R) that overcome these challenges by using mixtures of odorants that have unfamiliar smells. The tests can be self-administered with minimal training and showed high test-retest reliability. Because SMELL-S uses odor mixtures rather than a single molecule, odor-specific insensitivity is averaged out. Indeed, SMELL-S accurately distinguished people with normal and dysfunctional smell. SMELL-R is a discrimination test in which the difference between two stimulus mixtures can be altered stepwise. This is an advance over current discrimination tests, which ask subjects to discriminate monomolecular odorants whose difference cannot be objectively calculated. SMELL-R showed significantly less bias in scores between North American and Taiwanese subjects than conventional semantically-based smell tests that need to be adapted and translated to different populations. We predict that SMELL-S and SMELL-R will be broadly effective in diagnosing smell dysfunction, including that associated with the earliest signs of memory loss in Alzheimers disease.\n\nSignificance statementCurrently available smell testing methods can misdiagnose subjects with lack of prior experience or insensitivity to the odorants used in the test. This introduces a source of bias into clinical tests aimed at detecting patients with olfactory dysfunction. We have developed smell tests that use mixtures of 30 molecules that average out the variability in sensitivity to individual molecules. Because these mixtures have unfamiliar odors, and the tests are non-semantic, their use eliminates differences in test performance due to the familiarity with the smells or the words used to describe them. The SMELL-S and SMELL-R tests facilitate smell testing of diverse populations, without the need to adapt the test stimuli.

neuroscience↗