Normative values for the assessment of gustatory function using liquid tastants

Test-retest reliability and normative data for "Seven-iTT", a test for the assessment of taste and oral trigeminal function

BACKGROUND

Assessment of taste and somatosensory perception in clinical practice lacks fast tests that are validated and reliable. Recently, a 12-item identification test for taste and oral trigeminal perception, and its shorter version, the Seven-iTT, was developed. The objectives of this study were to evaluate its test-retest reliability and establish normative data.

NEW METHOD

Two-hundred participants (120 women, 80 men) with a good sense of taste performed a whole-mouth identification test using 12 filter-paper strips impregnated with low and high concentrations of sweet, sour, salty, bitter, astringency, and spiciness. Fifty of them repeated the task, with a median interval of 122 days from the first visit. Test-retest reliability was determined using Spearman correlation and the Bland-Altman plot method.

RESULTS

There was a significant correlation in identification score between the first and the second session for both versions of the test (r ≥ 0.28; p ≤ 0.048). The Bland-Altman plot reflected a good congruence between the results of the two sessions. Additionally, frequencies of correct identification were consistent between sessions, with women outperforming men (p = 0.005). Hypogeusia was established at Seven-iTT score of 3 of less.

COMPARISON WITH EXISTING METHODS

The identification test combines taste and somatosensory perception, thus creating a more detailed diagnosis tool. Scores were correlated with self-rated taste perception.

CONCLUSION

The present results confirmed the applicability of Seven-iTT for a reliable, fast evaluation of taste and somatosensory perception in the general population, that can be extended to clinical practice.

Time-frequency analysis of gustatory event related potentials (gERP) in taste disorders

In taste disorders, the key to a correct diagnosis and an adequate treatment is an objective assessment. Compared to psychophysical tests, EEG-derived gustatory event-related potentials (gERP) could be used as a less biased measure. However, the responses identified using conventional time-domain averaging show a low signal-to-noise ratio. This study included 44 patients with dysgeusia and 59 healthy participants, who underwent a comprehensive clinical examination of gustatory function. gERPs were recorded in response to stimulation with two concentrations of salty solutions, which were applied with a high precision gustometer. Group differences were examined using gERP analyzed in the canonical time domain and with Time-Frequency Analyses (TFA). Dysgeusic patients showed significantly lower scores for gustatory chemical and electrical stimuli. gERPs failed to show significant differences in amplitudes or latencies between groups. However, TFA showed that gustatory activations were characterized by a stronger power in controls than in patients in the low frequencies (0.1-4 Hz), and a higher desynchronization in the alpha-band (8-12 Hz). Hence, gERPs reflect the altered taste sensation in patients with dysgeusia. TFA appears to enhance the signal-to-noise ratio commonly present when using conventional time-domain averaging, and might be of assistance for the diagnosis of dysgeusia.

Effect of Age and Gender on Taste Function as Measured by the Waterless Empirical Taste Test

The effect of age and gender on taste function is rarely investigated. Therefore, we tried to study the effect of age and gender on taste function as evaluated by the Waterless Empirical Taste Test (WETT®). The WETT® consists of 40 strips that are coated with one of five tastants (sucrose, citric acid, sodium chloride, caffeine, or monosodium glutamate). Each tastant is prepared with four different concentrations. These 40 strips are interspersed with an additional 13 tasteless strips. To implement the WETT®, a strip was placed on the middle portion of the tongue. The subjects closed their mouth and tasted the strip. They then chose one of six answers (sweet, sour, salty, bitter, brothy, or no taste at all). If the answer was correct, one score was acquired. One-hundred-and-twenty healthy men and women were collected in this study. Among them, there were 40 subjects in each age group of 20-39 years, 40-59 years, and ≥60 years. The overall taste and individual tastant function decreased with age, particularly between subjects aged 20-39 years and those aged ≥60 years. The overall taste and individual tastant function were better in females than in males, especially for subjects aged older than 59 years. Our results show that taste function is affected by both age and gender.

A Simple Taste Test for Clinical Assessment of Taste and Oral Somatosensory Function-The "Seven-iTT"

Taste dysfunctions may occur, for example, after viral infection, surgery, medications, or with age. In clinical practice, it is important to assess patients' taste function with rapidity and reliability. This study aimed to develop a test that assesses human gustatory sensitivity together with somatosensory functions of astringency and spiciness. A total of 154 healthy subjects and 51 patients with chemosensory dysfunction rated their gustatory sensitivity. They underwent a whole-mouth identification test of 12 filter-paper strips impregnated with low and high concentrations of sweet, sour, salty, bitter (sucrose, citric acid, NaCl, quinine), astringency (tannin), and spiciness (capsaicin). The percentage of correct identifications for high-concentrated sweet and sour, and for low-concentrated salty, bitter and spicy was lower in patients as compared with healthy participants. Interestingly, a lower identification in patients for both astringent concentrations was found. Based on the results, we proposed the Seven-iTT to assess chemo/somatosensory function, with a cut-off of 6 out of 7. The test score discriminated patients from healthy controls and showed gender differences among healthy controls. This quantitative test seems to be suitable for routine clinical assessment of gustatory and trigeminal function. It also provides new evidence on the mutual interaction between the two sensory systems.

Validation of the clinical applicability of the brief self-administered waterless empirical taste test during the era of COVID-19

BACKGROUND

This study was performed to test the clinical applicability of a new taste test, the Brief Self-Administered Waterless Empirical Taste Test (B-WETT) in the era of COVID-19.

METHODS

Sixty healthy volunteers and 60 patients experiencing gustatory dysfunction were enrolled. All subjects received both the Self-Administered WETT and the new B-WETT which are comprised of disposable plastic strips containing sucrose, citric acid, sodium chloride, caffeine, and monosodium glutamate tastants to evaluate taste function. The healthy volunteers were re-tested with the WETT and B-WETT after an inter-test interval of at least 7 days to measure retest reliability.

RESULTS

The sum scores of five tastants of the first test were 25.7 for males and 29.5 for females in WETT, and 12.4 for males and 15.2 for females in B-WETT. There were significant differences in the sum scores between males and females whether in WETT or B-WETT. The sum scores strongly correlated between WETT and B-WETT, whether in healthy volunteers or in patients with gustatory dysfunction (r >0.7). There was also a strong correlation between the first and second tests of B-WETT for the sum scores.

CONCLUSION

This study shows that B-WETT is a valid and reliable taste test, and is convenient for use in the era of COVID-19 to evaluate the taste function of patients.

[Analysis of clinical characteristics in the patient with olfactory disorders]

Objective:To analyze the etiology and clinical features of patients with olfactory disorders （OD） , and to explore the importance of gustatory testing in patients with OD. Methods:Clinical data of 335 consecutive patients with OD who seek medical consultation in the smell and taste center from the year 2015 to 2021 was retrospectively analyzed. The clinical characteristics of patients with OD were analyzed thorough a structured interview of medical history, otolaryngologic examinations, olfactory tests（Sniffin' Sticks test） and gustatory function test（whole-mouth taste test）. SPSS 17.0 software was used to analyze the clinical characteristics of patients with OD and related factors which have effect on gustatory function. Results:Among the patients， 36.4% of them caused by head trauma, 22.1% for upper respiratory tract infection（URTI）, 15.5% for rhinosinusitis diseases（RSD）, 11.9% for idiopathic, 9.6% for congenital anosmia, and 4.5% for other causes, respectively. The features were different in patients with different kinds of OD: most patients with head trauma were anosmic（χ²=27.958, P<0.001）, and no difference was found in gender and age（P>0.05 for both）; most patients with URTI were anosmic（χ²=21.568, P<0.001）, and female patients were more than male（χ²=5.898, P<0.05）, elder patients were more than younger（χ²=12.963, P<0.001）; most patients with RSD were anosmic（χ²=12.106, P<0.05）, and male patients were more than female（χ²=4.655, P<0.05）; elder patients were more than younger for idiopathic OD（χ²=5.284, P<0.05）, but no sex difference was found（P>0.05）; patients with congenital anosmia were all lost their smell since they were born, and no sex difference was found in the disease（P>0.05）. Fifty-seven of 146（39%） patients whose gustation was assessed had gustatory dysfunction. Gustatory function was significantly associated with the causes of OD（r=0.368, P<0.05）, but not related to olfactory function, age and sex（P>0.05 for all）. Conclusion:The leading causes of olfactory dysfunction were head trauma, URTI, RSD, and idiopathic causes. Each of OD had its own distinct clinical features. Gustatory dysfunction were common in patients with OD, and gustatory function was related to the causes of OD. High priority should be given to gustatory function evaluation for the patients with OD.

Safety, Pharmacodynamics, and Pharmacokinetics of P2X3 Receptor Antagonist Eliapixant (BAY 1817080) in Healthy Subjects: Double-Blind Randomized Study

Background and Objective

There is no licensed treatment for refractory chronic cough; off-label therapies have limited efficacy and can produce adverse effects. Excessive adenosine triphosphate signaling via P2X3 receptors is implicated in refractory chronic cough, and selective P2X3 receptor antagonists such as eliapixant (BAY 1817080) are under investigation. The objective of the study was to investigate the safety and tolerability of ascending repeated oral doses of eliapixant in healthy volunteers.

Methods

We conducted a repeated-dose, double-blind, randomized, placebo-controlled study in 47 healthy male individuals. Subjects received repeated twice-daily ascending oral doses of eliapixant (10, 50, 200, and 750 mg) or placebo for 2 weeks. The primary outcome was frequency and severity of adverse events. Other outcomes included pharmacokinetics and evaluation of taste disturbances, which have occurred with the less selective P2X3 receptor antagonist gefapixant.

Results

Peak plasma concentrations of eliapixant were reached 3–4 h after administration of the first and subsequent doses. With multiple dosing, steady-state plasma concentrations were reached after ~ 6 days, and plasma concentrations predicted to achieve ≥ 80% P2X3 receptor occupancy (the level required for efficacy) were reached at 200 and 750 mg. Increases in plasma concentrations with increasing doses were less than dose proportional. After multiple dosing, mean plasma concentrations of eliapixant showed low peak–trough fluctuations and were similar for 200- and 750-mg doses. Eliapixant was well tolerated with a low incidence of taste-related adverse events.

Conclusions

Eliapixant (200 and 750 mg) produced plasma concentrations that cover the predicted therapeutic threshold over 24 h, with good safety and tolerability. These results enabled eliapixant to progress to clinical trials in patients with refractory chronic cough.

Clinical Trial Registration

Clinicaltrials.gov: NCT03310645 (initial registration: 16 October, 2017).

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01126-1.

There are few effective treatments for patients with a long-term (chronic) cough. It is thought that chronic cough is caused by nerves becoming oversensitive, wrongly causing a cough when there is no need. We tested a new drug called eliapixant in 47 healthy men. Eliapixant reduces the excessive nerve signaling responsible for chronic cough. We looked for side effects of eliapixant and measured how it behaves in the body. In particular we looked for side effects relating to the sense of taste because gefapixant, a similar drug to eliapixant, can affect taste. Participants took one of four eliapixant doses or a placebo twice daily for 2 weeks. The highest levels of eliapixant in the blood were seen 3–4 h after taking the drug, and stable concentrations were seen after about 6 days. At the two highest doses, eliapixant reached concentrations in the body that should be high enough to work in patients with chronic cough. Side effects were generally similar between eliapixant and placebo. Taste-related side effects were mild and went away without needing treatment. The positive results of this study meant that eliapixant could be tested in patients with chronic cough.

Gustatory event-related potential alterations in olfactory dysfunction patients

The phenomenon that longstanding impaired olfactory function is associated with the decreased gustatory function was described in present studies, which was seems attributed to mutual chemosensory interactions. And the interaction between olfaction and gustation still needs more research to figure out. The objective of the study was to investigate how the taste was influenced by olfactory impairment in the central pathway. We tested 33 subjects with normal (n = 19) or impaired (n = 14) olfactory function for their gustatory event-related potentials (gERPs). Validated tests were used for olfactory and gustatory testing (Sniffin’ Sticks, gERPs, and three-drop test). This study reported an objective gustatory function decline in olfactory dysfunction participants. However, it also reported the increased gustatory event-related potentials of olfactory dysfunction participants, especially at the frontal electrode (F_Z) and electrode 16 (E16), and the reduced latency of P2 peak of them at electrode 21 (E21), while no obvious difference was observed at the centro-parietal electrode (P_Z). Inferior insula might be the main response area for the increase in gERPs, and this increase averaged amplitude of the P2 component may attribute to compensation of the secondary gustatory response that occurred in the gustatory processing of olfactory-impaired patients.

Associations between Taste and Smell Sensitivity, Preference and Quality of Life in Healthy Aging-The NutriAct Family Study Examinations (NFSE) Cohort

Taste and smell function decline with age, with robust impairment in the very old. Much less is known about taste and smell function in young and middle aged. We investigated taste and smell sensitivity via thresholds in a sub-sample of the NutriAct Family Study (NFS), the NFS Examinations cohort (NFSE; N = 251, age M = 62.5 years). We examined different aspects relating to taste and smell function: the degree to which taste and smell sensitivity relate to another and to taste and smell preferences, the role of gender and age, as well as effects on Quality of Life (QoL). Taste thresholds were highly correlated, but no correlation was observed between taste and smell thresholds and between thresholds and preference. Women were more sensitive for both taste and smell than men. We found no effect of age on sensitivity and no effect of sensitivity on QoL. All null findings were complemented by Bayesian statistics. Together our results indicate the independence of taste and smell despite their overlap during sensorial experiences. We found no evidence for age-related sensory decline, which could be due to our sample’s characteristics of non-clinical volunteers with good dental health and 93% non-smokers.

Effect of cross-cultural differences on thickness, firmness and sweetness sensitivity

Sensitivity of the somatosensory system may be influenced by multiple physiological parameters. Variations in oral physiology can arise from cross-cultural differences which may potentially affect sensory sensitivity. The aim of this case study was to quantify texture and taste sensitivity in Dutch (Caucasian) and Chinese (Asian) adults living in the Netherlands. Eighty-five healthy subjects were recruited including 44 Dutch (Caucasian) adults (29 females, 22.8 ± 2.3 yrs) and 41 Chinese (Asian) adults (30 females, 24.5 ± 2.1 yrs) living in the Netherlands for less than 1 year. Three sets of stimuli were used to quantify sensitivity of thickness (maltodextrin solutions differing in viscosity), firmness (agar gels differing in fracture stress) and sweetness (sucrose solutions differing in concentration). The 2-Alternative Forced Choice (2-AFC) ascending staircase method was used to determine texture and taste sensitivity. Unstimulated and stimulated saliva flow rate, fungiform papillae density (FPD), lingual tactile threshold and PROP taster status were determined and are referred to as physiological and sensory consumer characteristics. No significant differences were observed between Chinese and Dutch adults for thickness (Dutch 2.60 mPas, Chinese 2.19 mPas), firmness (Dutch 10.5 kPa, Chinese 10.3 kPa) and sweetness sensitivity (Dutch 0.012 g/mL, Chinese 0.017 g/mL). No significant differences were observed between Chinese and Dutch adults for saliva flow rate, lingual tactile threshold and PROP taster status. The relationships between the three sensory sensitivities (thickness, firmness, sweetness) and five physiological and sensory consumer characteristics (unstimulated and stimulated saliva flow rate, FPD, lingual tactile threshold, PROP taster status) were analyzed. Only one out of 15 relationships, firmness sensitivity and FPD, was significantly and weakly related suggesting that inter-individual variation in these consumer characteristics is almost unrelated to sensory sensitivity. We conclude that in this case study thickness, firmness and sweetness sensitivities do not differ between Dutch and Chinese adults living in the Netherlands. Saliva flow rate, fungiform papillae density, lingual tactile threshold and PROP taster status do not explain inter-individual variation in sensory sensitivity between these consumers.

High prevalence of long-term olfactory dysfunction confirmed by olfactory testing after a community COVID-19 outbreak

Purpose

The prevalence of long-term olfactory and gustatory dysfunction in participants suffering from sudden chemosensory loss due to coronavirus disease 2019 (COVID-19) is unknown. Furthermore, evaluations of the reliability of participants’ self-reporting of olfactory function (SOF) and gustatory function (SGF) using extended objective psychophysical testing are missing.

Methods

In this population-based cohort study in a PCR-tested community in Thuringia, Germany, olfactory function was extensively examined 4 months after a COVID-19 outbreak using the “Sniffin Sticks” test battery to determine the TDI_a score, i.e., the sum of results obtained for threshold, discrimination, and identification scores averaged for both nasal sides. Gustatory function was assessed using the three-drop test resulting in the gustatory composite score (CS_g). The data were compared with SOF and SGF.

Results

Of 43 adult convalescents (median age: 68 years; 58% female) after SARS-CoV‑2 infection, 18 participants (42%) had olfactory complaints due to SOF, one participant (2%) complained of taste disturbance due to SGF. The TDI_a was 22.0 ± 5.9. Normosmia, hyposmia, and anosmia were seen in 17, 18, and eight participants, respectively. TDI_a correlated with SOF (r_s = −0.434, p = 0.004); CS_g was 23.5 ± 2.7. Normogeusia and hypogeusia were objectified in 39 and four participants, respectively. The prevalence of long-term olfactory dysfunction and gustatory dysfunction in the study group was 60.5 and 9.3%, respectively.

Conclusion

The SOF was reliable, especially for participants who felt a sudden chemosensory dysfunction during the outbreak. At 4 months after SARS-CoV‑2 infection, a high proportion of participants were dysosmic, whereas nearly all of them had normal taste function.

Normative data on the subjective gustatory function of Chinese adults

PURPOSE

the study aims to assess the gustatory function of healthy Chinese adults with the whole-mouth test based on five basic tastants, including umami taste.

METHODS

the study recruited 464 participants reporting a normal sense of smell/taste (227 females and 237 males with an age range of 19-65 years). A drop (approximately 0.1 mL) of liquid tastant was applied on the anterior third of the extended tongue of each subject. The taste solutions involved 5 tastants (sour, sweet, salty, umami, and bitter) and 7 concentrations. Taste perception scores and recognition scores of the five basic tastants were obtained with this whole-mouth taste method.

RESULTS

total taste score of recognition showed a significant negative correlation with age. The elder group (51-65 years) had the lowest scores. The 10th percentile of total taste score of recognition in the group of 36 to 50 years was used to distinguish normogeusic subjects from hypogeusic subjects. The perception scores and recognition scores of females were higher than those of males. The perception and recognition thresholds of salty, umami, and bitter for females were lower than those for males. Total taste score of recognition for non-smokers was significantly higher than that of smokers. The whole-mouth method showed a high test-retest reliability with an intra-class correlation coefficient (ICC) from 0.774 to 0.833.

CONCLUSION

this whole-mouth method is simple and time-saving and can be easily adjusted to obtain reliable data. The gustatory function was significantly negatively correlated with age. Females were more sensitive to the sour, salty, umami and bitter tastes than males. The gustatory function of non-smokers was more sensitive.

The Etiologies and Considerations of Dysgeusia: A Review of Literature

BACKGROUND

Dysgeusia is a prevalent qualitative gustatory impairment that may affect food intake and quality of life. The facial (VII), glossopharyngeal (IX), and vagus (X) nerves are the three cranial nerves responsible for sensing taste. Typically, dysgeusia is considered a general term for all taste disorders. In addition, dysgeusia may be a symptom of underlying systemic conditions such as diabetes mellitus, chronic kidney disease, respiratory infections, and nutritional deficiencies. Various subjective and objective diagnostic approaches are available to aid clinicians, each with its own set of benefits and drawbacks.

HIGHLIGHTS

Taste impairment can lead to a lack of enjoyment while eating, food aversion, and malnutrition, resulting in a decrease in the quality of life and loss of muscle mass. Therefore, the present review aims to address the probable etiologies, diagnostic aids, and management of dysgeusia. A broad search for studies was conducted using PubMed, Web of Science, Scopus, and Google Scholar. In addition, relevant studies found in the references of the selected articles were also studied.

CONCLUSION

Oral health care providers should be aware of the possible etiologies of dysgeusia, diagnostic tools, and treatment options. Accurate diagnosis of the cause of taste dysfunction has a significant impact on the management of taste impairment.

Assessment of gustatory function in aging people using event-related potentials

Gustatory dysfunctions are more frequent than other chemosensory dysfunctions in aging people. Gustatory event-related potentials (ERPs) has been suggested as a reliable and effective approach for assessing gustatory functions in young and middle subjects, but has rarely been investigated in aging people, leaving influencing factors of ERPs in that population not completely understood. In this study, we analyzed gustatory ERPs results of aging participants and characterized potential impacting factors, including age, sex, BMI, drinking, smoking, hypertension, diabetes, cognition and psychophysical test scores of gustation and olfaction. Our results revealed three components (P1, N1 and P2) in gustatory ERPs upon salty stimulation. Significant differences between responses collected from different recording electrodes were observed: minimum latencies and maximum amplitudes of P1 were detected at frontal electrode, and maximum amplitudes of N1 and P2 were detected at central and centro-parietal electrodes, respectively. Major cortical sources of components P1, N1 and P2 were located at bilateral insula, frontal operculum, and orbitofrontal cortex. Diabetes was positively associated with latencies of P1. Sex was positively associated with amplitudes of P1, N1 and P2. Hypertension was negatively associated with amplitudes of P1 and P2. In conclusion, gustatory ERPs in aging people exhibited a specific topographical distribution, represented by sex-related differences and negative impacts of diabetes and hypertension.

Taste dysfunction in children - a clinical perspective and review of assessment methods

Taste dysfunction has been associated with aging and is therefore thought to be less common in children. However, children can face medical conditions influencing their taste function. Measuring and understanding taste dysfunction in children may foster the development of treatments/interventions mitigating the detrimental effects of taste dysfunction on children's appetite and quality of life. But measuring loss of taste function requires adequate tools. This review was conducted to (1) provide an overview of etiologies (i.e., disease and iatrogenic) associated with taste dysfunction in a pediatric population; (2) to investigate which tools (psychophysical tests and questionnaires) are available to assess taste function in children; and (3) to identify what tools can be and are actually used in clinical practice. It is concluded that only a minority of available tools to assess taste function in children are readily suitable for a pediatric clinical setting. Considering the profound impact of taste dysfunction in the pediatric setting, developing and implementing a standard taste test that is sensitive, simple, and practical to use with children is pertinent.

[Reliability of whole-mouth taste test in assessment of gustatory function in healthy adults]

Objective:The purpose of this study was to evaluate the test-retest reliability of gustatory function using whole-mouth taste tests in healthy adults. Methods:Fifty healthy subjects were tested by whole-mouth taste test. The taste test involved 5 tastants（sour, sweet, salty, umami and bitter） and 7 concentrations. The tastant solutions were administered in a pseudo-random order starting with the lowest concentration. Record the perception and recognition scores of each tastant separately. The same operator performed test again by the same method two weeks later. The relative reliability and absolute reliability of the whole-mouth taste test were evaluated with intraclass correlation coefficient（ICC） and standard errors of measurement（SEM）, SEM% respectively. Results:The intraclass correlation coefficient of the perception scores of the sour, sweet, salty, umami and bitter in healthy subjects were from 0.753 to 0.819, ICC values of recognition score range from 0.751 to 0.828. In terms of absolute reliability, the SEM and SEM% values of perception scores were 0.329-0.463 and 6.60%-9.07% respectively; SEM of recognition scores were 0.425-0.581 and SEM%=9.09%-14.66%. Conclusion:The whole-mouth taste test could be a reliable tool for gustatory function test with good test-retest reliability in healthy adults.

Peri-threshold Trigeminal Stimulation with Capsaicin Increases Taste Sensitivity in Humans

Introduction

Taste perception is affected by trigeminal stimuli, i.e., capsaicin. This has been studied at suprathreshold concentrations. However, little is known about taste perception at threshold level in the presence of low concentration of capsaicin. The aim of the study was to explore whether taste sensitivity for sweet, sour, salt, bitter, and umami is modulated by the presence of capsaicin in the peri-threshold range.

Methods

Fifty-seven adults (age range 19–85 years; 32 women) with functional gustation participated in the study. Based on their perception of phenylthiocarbamide (PTC), the group was stratified into non-tasters (n = 20) and tasters (n = 37). Threshold for sweet (sucrose), sour (citric acid), salty (sodium chloride), bitter (quinine-hydrochloride), and umami (sodium-glutamate) tastes was estimated using a single-staircase paradigm (3-alternative forced choice; volume per trial 0.1 ml) with or without 0.9-µM capsaicin added. This capsaicin concentration had been determined in pilot studies to be in the range of oral perception thresholds.

Results

The addition of capsaicin produced lower taste thresholds for sweet, sour, salty, and bitter but not for umami. In contrast, neither PTC taster status nor sex affected these results.

Conclusion

The current results indicate that a low concentration of capsaicin increases gustatory sensitivity.

Implications

The current findings provide evidence supporting different effects of capsaicin on taste perception at threshold level. It has implications for boosting taste sensitivity or flavor enjoyment with low concentration of capsaicin.

Assessment of Taste Function

Taste disorders, impacting well-being and physical health, can be caused by many etiologies including the use of medication. Recently, taste disturbance is also considered as one of the predominant symptoms of COVID-19 although its pathogenesis requires further research. Localized taste disorders may be overlooked considering that whole-mouth taste perception is insured through several mechanisms. Individuals often fail to discern taste from flavor, and interviews/surveys are insufficient to properly assess taste function. Hence, various taste assessment methods have been developed. Among them, psychophysical methods are most widely applied in a clinical context. Less-biased electrophysiological, imaging, or morphological methods are used to a much lesser degree. Overall, more research is needed in the field of taste.

Avaliação do paladar de idosos e sua relação com estado nutricional e hábitos alimentares

Objetivos: avaliar a prevalência de disgeusia (distorção ou diminuição do paladar) e a associação com o estado nutricional e as práticas alimentares em um grupo de idosos, assim como identificar os gostos mais afetados e preservados.Métodos: estudo transversal com amostra recrutada no Centro de Lazer para idosos no município de Porto Alegre, RS. Avaliou-se o paladar, através de tiras gustativas (“tastestrips”), e o estado nutricional, através do Índice de Massa Corporal. As práticas alimentares foram investigadas através de questionário. Para análise estatística utilizou-se os testes qui-quadrado e ANOVA, com nível de significância de p <0,05.Resultados: foram avaliados 62 idosos (84% feminino, média de 70±7,6 anos), prevalência de disgeusia foi 19,4% (n=12), detectou-se 58% de sobrepeso (n=36), 40,5% de eutrofia (n=25) e 1,5% de baixo peso (n=1), não sendo encontrada associação entre alteração de paladar e estado nutricional (p=0,397). Cerca de 55% dos idosos apresentaram consumo elevado de sódio. Não houve diferença na média de pontos para o gosto ácido entre os idosos que temperam a salada com limão ou vinagre e os que não o fazem (p=0,054 e p=0,935, respectivamente). A média de pontos para o gosto salgado não diferiu entre os que preparam as refeições com temperos ricos em sódio e os que não os utilizam (p=0,055). O doce foi o gosto mais preservado, enquanto o ácido mostrou-se mais reduzido.Conclusões: apesar de evidências contrárias, não se identificou impacto das alterações de paladar sobre o estado nutricional e as práticas alimentares. Ainda assim, novos estudos que incluam essas variáveis se fazem necessários.

A Pilot Study of the Waterless Empirical Taste Test

OBJECTIVES

This study was performed to test the clinical applicability of a new taste test-the waterless empirical taste test (WETT).

METHODS

Sixty healthy volunteers and 20 patients with oral cancer were enrolled. They all received the conventional solution-based whole-mouth suprathreshold taste test (WMTT), which contained sucrose, citric acid, sodium chloride, and caffeine solutions for tastants, along with the WETT. The WETT used plastic strips to deliver tastants. The strip was embedded with sucrose, citric acid, sodium chloride, caffeine, or monosodium glutamate taste enhancer in 4 different concentrations. Each strip was tested twice. Thirty of the healthy volunteers received the WETT again to measure a retest reliability. Case-control matching by age and gender was used to compare the scores of WMTT and WETT between 13 healthy volunteers and 13 patients with oral cancer.

RESULTS

The correlation was not high between the WMTT and WETT (r < 0.7) whether in the healthy volunteers or in patients with oral cancer. In terms of retest reliability of the WETT, the mean total score was 24.9 ± 7.3 for the first test and 25.8 ± 8.4 for the second test. The intraclass correlation coefficient was 0.85 (P < .001). When case-control matching was performed, the WMTT scores were not significantly different between 13 healthy volunteers and 13 patients with oral cancer (P = .266), but the WETT scores were significantly lower in patients with oral cancer (P = .017).

CONCLUSION

This study showed that the results of the WETT were not highly correlated with those of the WMTT. However, its retest reliability was high, and its results were significantly different between the healthy volunteers and the patients with oral cancer.

Assessment of odor hedonic perception: the Sniffin' sticks parosmia test (SSParoT)

Qualitative olfactory dysfunction is characterized as distorted odor perception and can have a profound effect on quality of life of affected individuals. Parosmia and phantosmia represent the two main subgroups of qualitative impairment and are currently diagnosed based on patient history only. We have developed a test method which measures qualitative olfactory function based on the odors of the Sniffin' Sticks Identification subtest. The newly developed test is called Sniffin' Sticks Parosmia Test (SSParoT). SSParoT uses hedonic estimates of two oppositely valenced odors (pleasant and unpleasant) to assess hedonic range (HR) and hedonic direction (HD), which represent qualitative olfactory perception. HR is defined as the perceivable hedonic distance between two oppositely valenced odors, while HD serves as an indicator for overall hedonic perception of odors. This multicenter study enrolled a total of 162 normosmic subjects in four consecutive experiments. Cluster analysis was used to group odors from the 16-item Sniffin' Sticks Identification test and 24-additional odors into clusters with distinct hedonic properties. Eleven odor pairs were found to be suitable for estimation of HR and HD. Analysis showed agreement between test-retest sessions for all odor pairs. SSparoT might emerge as a valuable tool to assess qualitative olfactory function in health and disease.

More Than Smell-COVID-19 Is Associated With Severe Impairment of Smell, Taste, and Chemesthesis

Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, and generally lacked quantitative measurements. Here, we report the development, implementation and initial results of a multi-lingual, international questionnaire to assess self-reported quantity and quality of perception in three distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19. In the first 11 days after questionnaire launch, 4039 participants (2913 women, 1118 men, 8 other, ages 19-79) reported a COVID-19 diagnosis either via laboratory tests or clinical assessment. Importantly, smell, taste and chemesthetic function were each significantly reduced compared to their status before the disease. Difference scores (maximum possible change ±100) revealed a mean reduction of smell (-79.7 ± 28.7, mean ± SD), taste (-69.0 ± 32.6), and chemesthetic (-37.3 ± 36.2) function during COVID-19. Qualitative changes in olfactory ability (parosmia and phantosmia) were relatively rare and correlated with smell loss. Importantly, perceived nasal obstruction did not account for smell loss. Furthermore, chemosensory impairments were similar between participants in the laboratory test and clinical assessment groups. These results show that COVID-19-associated chemosensory impairment is not limited to smell, but also affects taste and chemesthesis. The multimodal impact of COVID-19 and lack of perceived nasal obstruction suggest that SARS-CoV-2 infection may disrupt sensory-neural mechanisms.

Influence of age and sex on taste function of healthy subjects

The purpose of this study was to determine the influence of age and sex on the taste functions of healthy Taiwanese. Subjects were divided into groups based on their sex and age: 20-39 years, 40-59 years, or ≥ 60 years. We evaluated the taste functions of subjects using the whole mouth suprathreshold taste test and the taste quad test. For the whole-mouth test, subjects were instructed to sip and swish sweet, sour, salty, and bitter solutions, each at 5 different suprathreshold concentrations. Each subject was required to indicate the taste quality, and to rate the intensity and unpleasantness/pleasantness of each taste of the solutions. For the quad test, the 4 quadrants of the tongue surface were tested by applying a drop of one concentration of sweet, sour, salty, or bitter solutions 6 times. Subjects then indicated the taste quality and rated the intensity of the solution. We found that in the whole mouth test, the total correct identification score dropped with age, but the ability to identify sweet and salty qualities was not affected by age. No differences were found between males and females, except women scored better than men for sweetness in the 40-59 years age group. The intensity rating scores were higher in the 20-39 years age group, regardless of sex. With regard to the pleasantness of tastants, female subjects in the 20-39 years age group found sweet solution more pleasant than the older subjects did. In the quad test, the total correct identification score decreased with age, but there were no differences between males and females. Thus, our findings showed that both age and sex affected the taste functions of healthy Taiwanese to some extent, and differences were dependent on tongue region and taste quality.

The impact of obstructive apnea sleep syndrome on chemical function

OBJECTIVE/HYPOTHESIS

To investigate the impact of obstructive sleep apnea syndrome (OSAS) on the olfactory and gustatory functions, and the potential mechanisms affecting olfactory and gustatory functions.

MATERIALS AND METHODS

A total of 120 men between the ages of 41 and 70 (mean age (SD) = 56 ± 7.5) were divided into three groups according to polysomnography results: snoring group, mild to moderate OSAS group, and severe OSAS group. Olfactory and gustatory functions were evaluated by the Sniffin' Sticks test and the triple-drop method, respectively. Otorhinolaryngologic examination, as well as sleep and quality of life questionnaires, were completed by all subjects one day before or after polysomnography.

RESULTS

There was a significant difference in odor thresholds (THR), odor discrimination (OD), odor identification (OI), thresholds-discrimination-identification (TDI) (p < 0.001, p < 0.001, p = 0.003, p < 0.001), and total taste score (p = 0.004, p = 0.021, p = 0.006) in all three groups. Of the subjects in the OSAS group, 43 (54%) exhibited olfactory dysfunction, including 18 subjects (45%) in the mild to moderate group and 25 subjects (63%) in the severe group. Significant negative correlations were found between all olfactory parameters and polysomnography parameters. Furthermore, a negative correlation was present between the total taste scores and the apnea-hypopnea index (AHI).

CONCLUSION

Men with OSAS exhibited impairment in olfactory and gustatory functions. Significant correlations were found between AHI and olfactory parameters, as well as between AHI and total taste scores.

Bitter Taste Perception of the Human Tongue Mediated by Quinine and Caffeine Impregnated Taste Strips

Objectives:

Tests for gustatory function have become increasingly important in diagnosis and treatment of patients with taste disorders. While caffeine and quinine hydrochloride solutions have been used for global testing of bitter perception, only quinine has been used to test regional bitter perception by means of taste strips. The aim of the present study was to validate caffeine impregnated taste strips as an alternative to quinine taste strips for assessment of regional bitter perception.

Methods:

A total of 46 healthy volunteers (mean age/range, 23/19-27 years) were included in this study. Quinine and caffeine impregnated taste strips were pairwise presented at different parts of the tongue. Perceived intensity and hedonic dislike were evaluated using labeled magnitude scales. Additionally, gustatory function was assessed using the taste strips test and overall sense of taste was rated using visual analog scales.

Results:

Assessment of gustatory function demonstrated scores within the normogeusic range in most included subjects (mean/SD, 13.1/2.5). Notably, equally concentrated quinine and caffeine impregnated taste strips placed on different regions of the tongue did not lead to significant differences in perceived intensity or hedonic dislike, whereas quinine and caffeine impregnated taste strips of different concentrations placed on the same region on the tongue led to significant differences of perceived intensity and hedonic dislike. Furthermore, no correlation was found between self-assessment of gustatory function and taste strips scores.

Conclusion:

Caffeine seems to be a valid bitter compound for regional testing using taste strips and may be used alternatively to quinine.

Taste Function in Healthy Taiwanese Adults

Objective

In this work, our aim was to measure the taste function of healthy Taiwanese adults using 2 commonly used taste tests.

Methods

The taste function of 102 healthy Taiwanese adults was evaluated using the whole-mouth suprathreshold taste test and the taste quad test. In the whole-mouth taste test, 5 concentrations of sweet, bitter, sour, and salty solutions were sipped and swished in the mouth twice in a counterbalanced order. A total of 40 tests were done to give a maximum score of 40 for correct quality identification of tastant solutions. In the taste quad test, the 4 quadrants of the tongue were tested using high concentration drops of sweet, bitter, sour, and salty solutions 6 times. A total of 96 tests were done to give a maximum score of 96 for correct quality identification of tastant solutions.

Results

The score of the whole-mouth taste test ranged from 33 to 40 with a mean of 38.6 for men and from 31 to 40 with a mean of 38.9 for women. The score of the taste quad test ranged from 40 to 91 with a mean of 75 for men and from 38 to 96 with a mean of 78 for women. Sex was shown not to affect the taste function.

Conclusions

Our result showed that sex did not affect the taste function of healthy Taiwanese adults.

Re-Test Reliability of Gustatory Testing and Introduction of the Sensitive Taste-Drop-Test

The sense of taste holds a key integrate role in assessing the flavor of food before swallowing is initiated. If the expectations for taste are not met, palatability and pleasure of the food can decrease. In patients suffering from taste disorders, this may impair appetite and nutritional state. Testing gustatory function can be important for diagnostics and assessment of treatment effects. However, the gustatory tests applied are required to be both sensitive and reliable. In this study, we investigate the re-test validity of popular Taste Strips gustatory test for gustatory screening. Furthermore, we introduce a new sensitive Taste-Drop-Test, which was found to be superior for detecting a more accurate measure of tastant sensitivity.

Development of a Gustatory Function Test for Clinical Application in Korean Subjects

PURPOSE

To obtain validated clinical values suitable for developing a gustatory function test, including umami taste, in a Korean population.

MATERIALS AND METHODS

The investigation involved 297 participants with self-reported normal sense of taste and smell. Liquid solutions were used for the assessment of gustatory function. The test consisted of 30 taste solutions [six concentrations of five tastants (sweet, bitter, salty, sour, and umami)]. For evaluation of overall gustatory function, the number of detected or correctly recognized taste thresholds was combined to form a "taste score."

RESULTS

Mean values of each detection and recognition threshold for the five tastes in men were consistently lower than those of women. The 10th percentile of taste score for recognition was used as the cut-off value for distinguishing normogeusia from hypogeusia. In subgroup analysis, total taste score from recognition thresholds revealed a significant negative correlation with age, indicating lower scores for increasing age. Taste score for non-smokers was significantly higher than that of smokers, in terms of detection and recognition of taste sensitivities.

CONCLUSION

This gustatory function test was easy to perform, affordable, and time-saving, with the capacity to self-produce and obtain reliable data. Gustatory function was more sensitive in young people, women, and non-smokers.

Influence of Japanese consumer gender and age on sensory attributes and preference (a case study on deep-fried peanuts)

BACKGROUND

Detailed exploration of sensory perception as well as preference across gender and age for a certain food is very useful for developing a vendible food commodity related to physiological and psychological motivation for food preference. Sensory tests including color, sweetness, bitterness, fried peanut aroma, textural preference and overall liking of deep-fried peanuts with varying frying time (2, 4, 6, 9, 12 and 15 min) at 150 °C were carried out using 417 healthy Japanese consumers. To determine the influence of gender and age on sensory evaluation, systematic statistical analysis including one-way analysis of variance, polynomial regression analysis and multiple regression analysis was conducted using the collected data.

RESULTS

The results indicated that females were more sensitive to bitterness than males. This may affect sensory preference; female subjects favored peanuts prepared with a shorter frying time more than male subjects did. With advancing age, textural preference played a more important role in overall preference. Older subjects liked deeper-fried peanuts, which are more brittle, more than younger subjects did.

CONCLUSION

In the present study, systematic statistical analysis based on collected sensory evaluation data using deep-fried peanuts was conducted and the tendency of sensory perception and preference across gender and age was clarified. These results may be useful for engineering optimal strategies to target specific segments to gain greater acceptance in the market. © 2017 Society of Chemical Industry.

Exploring Ethnic Differences in Taste Perception

It is well known that nutritional intake can vary substantially as a function of demographic variables such as ethnicity and/or sex. Although a variety of factors are known to underlie the relationship between these demographic variables and nutritional intake, it is interesting to speculate that variation in food intake associated with ethnicity or sex may result, in part, from differences in the perceived taste of foods in these different populations. Thus, we initiated a study to evaluate taste responsiveness in different ethnic groups. Moreover, because of the known differences in taste responsiveness between males and females, analyses were stratified by sex. The ethnic groups tested differed significantly from one another in reported perceived taste intensity. Our results showed that Hispanics and African Americans rated taste sensations higher than non-Hispanic Whites and that these differences were more pronounced in males. Understanding the nature of these differences in taste perception is important, because taste perception may contribute to dietary health risk. When attempting to modify diet, individuals of different ethnicities may require personalized interventions that take into account the different sensory experience that these individuals may have when consuming foods.

A self-administered test of taste function using "Taste Strips"

BACKGROUND

Assessment of gustatory function with impregnated taste strips is an established and validated method. In clinical routine, application of the tests is often limited due to lack of time or costs associated with administering the test. The aim of the study was to develop a procedure suitable for self-administration of the "Taste Strips" test.

METHODS

The investigated participants (n = 65; 22 males, 43 females; mean age 36.7 ± 19.2 years; range, 20 to 83 years) were tested twice in a randomized crossover procedure. On 1 occasion, an examiner administered the established and validated "Taste Strips" test. On another occasion, test subjects administered the taste strips themselves. Results of both test methods were compared.

RESULTS

The mean score (± standard deviation [SD]) of the assisted taste test (11.6 ± 2.6) was significantly lower compared to the mean self-administered taste test that yielded 12.3 ± 2.6 points (Wilcoxon test: z = 2.836; p < 0.01). Comparison of mean values showed minimal difference of the tested procedures of 0.7 ± 1.9 points with a significant positive correlation of test results (r65 = 0.734; p < 0.01).

CONCLUSION

Although a small difference between test results was observed, the new test procedure seems to be an adequate screening tool for assessment of taste function with less personnel effort, leading to improved management of patients with chemosensory disorders.

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.

No Difference in Perceived Intensity of Linoleic Acid in the Oral Cavity between Obese and Nonobese Individuals

Findings from studies examining interactions between fat taste and dietary fat intake or body weight are mixed. A convenience sample of 735 visitors to the Denver Museum of Nature & Science ≥8 years old rated the taste intensity of edible taste strips impregnated with varying concentrations (%v/v) of linoleic acid (LA) (blank = 0.0, low = 0.06, medium = 0.15, high = 0.38). Percent body fat (BF%) was measured using bioelectrical impedance. Fat taste intensity was rated as significantly different across all concentrations (P < 0.001) except between the blank and low concentrations (P = 0.1). Ratings increased monotonically across concentrations. Children (<18 years; N = 180) rated all concentrations as more intense than adults (P < 0.001 for all). Women and girls rated the highest concentration as more intense than men and boys (P < 0.02 for all). BF% was not correlated with fat taste intensity ratings. Self-reported dietary intake indicated that obese individuals’ intensity ratings for medium and high concentrations of LA were inversely related to recent mono- and poly-unsaturated fat exposure (r = −0.19 to −0.27; P < 0.03 for all). No such associations were observed in the nonobese group. Findings suggest that factors other than simple adiposity status influence fat taste intensity ratings, and that participants in fat taste studies should receive standardized meals prior to testing.

Impaired taste and increased mortality in acutely hospitalized older people

Taste ability is known to be impaired in elderly and even more so in acutely hospitalized elderly people. To our knowledge, no study has investigated the association between taste impairment and mortality. Our aim was to examine this association in acutely hospitalized older people. In a prospective study, 200 acutely hospitalized elderly people ≥70 years of age were included between November 2009 and October 2010 at the Oslo University Hospital, Norway. Exclusion criteria were cognitive impairment, nursing home residency, and terminal diseases. Comorbidity was registered with the Cumulative Illness Rating Scale, in addition to recording of age, gender, smoking, education, and number of medications. Taste ability was assessed quantitatively with the "taste strips method" in 174 patients (mean age: 84 years). Mortality until 1 January 2012 was obtained from hospital records. Fifty-six patients died during the observation period. The relative risk of death in total taste score quartile 4 compared with total taste score quartile 1 was 0.31 (95% confidence interval [95% CI]: 0.14-0.69, P = 0.004), after adjusting for age, gender, smoking, education, and Cumulative Illness Rating Scale. Adjusted 1-year mortality decreased from 30% in total taste score quartile 1 to 9% in total taste score quartile 4. Thus, impaired taste appears to be strongly associated with mortality in acutely hospitalized elderly people.

Prognostication of recovery time after acute peripheral facial palsy: a prospective cohort study

OBJECTIVE

Owing to a lack of prospective studies, our aim was to evaluate diagnostic factors, in particular, motor and non-motor function tests, for prognostication of recovery time in patients with acute facial palsy (AFP).

DESIGN

Prospective cohort study.

SETTING

University hospital.

PARTICIPANTS

259 patients with AFP.

MEASUREMENTS

Clinical data, facial grading, electrophysiological motor function tests and other non-motor function tests were assessed for their contribution to recovery time.

RESULTS

The predominant origin of AFP was idiopathic (59%) and traumatic (21%). At baseline, the House-Brackmann scale (HB) was >III in 46% of patients. Follow-up time was 5.6±9.8 months with a complete recovery rate of 49%. The median recovery time was 3.5 months (95% CI 2.2 to 4.7 months). The following variables were associated with faster recovery: Interval between onset of AFP and treatment <6 days versus ≥6 days (median recovery time in months 2.1 vs 6.5; p<0.0001); HB ≤III vs >III (2.2 vs 4.6; p=0.001); no versus presence of pathological spontaneous activity in first electromyography (EMG; 2.8 vs probability of recovery <50%; p<0.0001); no versus voluntary activity in EMG (probability of recovery <50% vs 3.1; p<0.0001); normal versus pathological ipsilateral electroneurography (1.9 vs 6.5; p=0.008), normal versus pathological stapedius reflexes (1.6 vs 3.3; p=0.003).

CONCLUSIONS

Start of treatment and grading, but most importantly EMG evaluated for pathological spontaneous activity and the stapedius reflex test are powerful prognosticators for estimating the recovery time from AFP. These results need confirmation in larger datasets.

Individual differences in sour and salt sensitivity: detection and quality recognition thresholds for citric acid and sodium chloride

Taste sensitivity is assessed with various techniques, including absolute detection and quality recognition. For any stimulus, one might expect individual differences in sensitivity to be reflected in all measures, but they are often surprisingly independent. Here, we focus on sensitivity to sour and salty taste, in part because processing of these qualities is poorly understood relative to other tastes. In Study 1, we measured retest reliability for detection (modified, forced-choice staircase method) and recognition (modified Harris-Kalmus procedure) for both citric acid (CA) and sodium chloride (NaCl). Despite good retest reliability, individual differences in detection and recognition were weakly correlated, suggesting that detection and recognition of sour and salty stimuli may reflect different physiological processes. In Study 2, a subset of subjects returned to contribute full detection (psychometric) functions for CA and NaCl. Thresholds estimated from full detection functions correlated with both staircase and recognition thresholds, suggesting that both tasks may reflect absolute sensitivity to some extent. However, the ranges of individual differences were systematically compressed for staircase thresholds relative to those from full detection functions. Thus, individual differences in sensitivity appear to interact with different test methodologies in lawful ways. More work will be required to understand how different taste phenotypes relate to one another.

Revisão: metodologias para análise da sensibilidade gustativa ao sal

A avaliação da sensibilidade gustativa ao sal é utilizada na área da saúde, bem como em análise sensorial aplicada à Ciência e Tecnologia de Alimentos, para avaliar o paladar e identificar ageusia e hipoageusia de diversas origens; notavelmente, identifica os indivíduos que apresentam risco ou consumo excessivo de sal. A adoção de um método acurado e reprodutível para avaliação do limiar gustativo ao sal permite seu uso de forma ampliada. Esta revisão integrativa tem como objetivo descrever as metodologias empregadas para avaliar o limiar de detecção e reconhecimento do cloreto de sódio. Foram utilizadas as bases de dados CINAHAL, LILACS e MEDLINE, e as palavras-chave taste threshold, sodium chloride e salt. Foram localizados 27 artigos de 1985 a 2009 e, nestes, empregados 29 testes de análise do limiar. A maioria dos artigos utilizou o estímulo da boca toda (75,9%), seguida da aplicação tópica na língua (24,1%), aplicação da solução em partes da língua (10,3%), eletrogustometria (6,4%), disco impregnado (3,4%) e aplicação de vácuo (3,4%). Houve grande variação nos procedimentos metodológicos e, em alguns, ausência de informações importantes. Os artigos não apresentam cálculo do tamanho amostral e os critérios de seleção dos julgadores foram também variados. Assim, existe uma dificuldade para a reprodutibilidade e as comparações dos artigos. Avaliações comparativas entre os diferentes métodos de avaliação do limiar gustativo ao cloreto de sódio quanto à sua reprodutibilidade podem trazer subsídios importantes para a escolha do método mais adequado a ser empregado em pesquisa e na prática clínica.

Examination of chemosensory functions in patients with dysosmia

Background

To examine changes of chemical sensory functions in patients with dysosmia.

Material/Methods

The 272 study subjects included 98 healthy volunteers, 86 subjects with hyposmia and 88 subjects with functional anosmia. Their chemical sensory functions were examined using olfactory event-related potentials (oERPs), trigeminal event-related potentials (tERPs), T&T olfactometer and triple drop method, respectively.

Results

The T&T results showed that the difference between patients and healthy subjects had statistical significance. The oERPs and tERPs results showed that patients with functional anosmia had N1 and P2 waves of prolonged latency and reduced amplitude when compared to healthy subjects with the difference of statistical significance. When compared to healthy subjects, patients with functional anosmia had clear hypogeusia and the difference had statistical significance. For the younger group there was significant difference between healthy subjects and patients in T&T, oERPs and tERPs results.

Conclusions

It is suggested by the apparently concomitant trigeminal nerve dysfunction and hypogeusia in patients with functional anosmia in this study that olfactory and nasal trigeminal function in young patients was clearly decreased. Our study suggests the possible application of oERPs, tERPs and three drops method in clinical diagnosis in Chinese populations and provides scientific evidence for treatment.

Smell and taste disorders

Smell and taste disorders can markedly affect the quality of life. In recent years we have become much better in the assessment of the ability to smell and taste. In addition, information is now available to say something about the prognosis of individual patients. With regard to therapy there also seems to be low but steady progress. Of special importance for the treatment is the ability of the olfactory epithelium to regenerate.

Gustatory function after radiofrequency tongue base reduction in patients with obstructive sleep apnea

OBJECTIVES

To investigate the changes in gustatory function as a complication after radiofrequency tongue base reduction (RTBR) in patients with obstructive sleep apnea (OSA).

STUDY DESIGN

Before-and-after study.

SETTING

Academic tertiary medical center.

SUBJECTS AND METHODS

Thirty-four patients with suspected velopharyngeal collapse only underwent uvulopalatopharyngoplasty (UPPP group). Twenty-five patients with velopharyngeal and retrolingual collapse underwent concurrent UPPP with RTBR (RTBR group). All patients were evaluated before surgery and at 1 and 4 weeks after surgical treatment. A questionnaire was given to assess symptoms of hypogeusia, dysgeusia, hyposmia, and sensation of the tongue. Electrogustometry (EGM) in 4 areas was used to determine gustatory function.

RESULTS

Postoperative values for subjective symptoms did not significantly change following surgical treatment in either group. EGM thresholds of all tested in both groups did not significantly change 1 week and 4 weeks after surgery.

CONCLUSIONS

Gustatory function remained unchanged after RTBR in patients with OSA. The authors suggest that RTBR is a safe procedure in terms of taste sensation in OSA patients.

A study about the frequency of taste disorders

Although 5% of the general population exhibit a functional anosmia, little is known about the frequency of gustatory disorders. Whenever taste function has been tested within large sociodemographic studies, so far only short test versions were applied making the interpretation difficult. Using two psychophysical taste tests, the validated "taste strips" and suprathreshold taste solutions of the four basic tastes sweet, sour, salty and bitter we investigated 761 healthy subjects within the age range of 5-89 years. Prior to testing, all subjects rated their taste function. According to testing with the taste strips, 5.3% scored below the result considered as hypogeusia. All four taste sprays were correctly identified by 82.3% of all subjects. Results of the two taste tests correlated positively (r = 0.33, p < 0.001), and there was a significant negative correlation between age and test results. However, we never observed complete ageusia. Misinterpretations of tastes were surprisingly common. In summary, hypogeusia was present in 5% while complete ageusia seems to be very rare, in contrast to misinterpretations of tastes.

Olfactory and gustatory function in healthy adult Chinese subjects

OBJECTIVE: To investigate the effect of age and gender on olfactory and gustatory function and to establish test methodology and normative values in Chinese subjects.

STUDY DESIGN: Cross-sectional study.

SETTING: The center laboratory and the Department of Otolaryngology—Head & Neck Surgery, Beijing Tongren Hospital.

SUBJECTS AND METHODS: The T&T olfactometer, the Sniffin' Sticks olfactory test, olfactory event-related potentials (oERPs), trigeminal event-related potentials (tERPs), and the triple drop method for gustatory testing were used to examine the chemosensation in 90 healthy adults (45 men and 45 women).

RESULTS: Older subjects (age 51–65 years) showed worse olfaction compared with younger subjects (age 18–35 years) when both T&T (younger —1.71 ± 0.41, older —0.92 ± 0.95; P < 0.01) and Sniffin' Sticks (threshold, discrimination, identification score: younger 33.17 ± 2.83, older 30.89 ± 3.35; P < 0.05) testing were performed. Measurement of oERPs revealed that older patients (N1 471 ± 85 ms, P2 676 ± 93 ms) had longer latencies compared with younger ones (N1 368 ± 57 ms, P2 561 ± 74 ms, P < 0.05) of N1/P2 wave. The results of trigeminal nerve-related potential examination showed that N1/P2 latencies were longer and amplitudes were lower in older people (N1 384 ± 98 ms/—5.01 ± 4.00 uv, P2 568 ± 95 ms/6.53 ± 3.62 uv) compared with younger patients (N1 316 ± 31 ms/—7.20 ± 3.43 uv, P2 472 ± 66 ms/8.72 ± 3.09 uv; P < 0.05). Gustation was normal in all subjects, and there was no significant difference between younger and older groups.

CONCLUSION: Age and gender affect olfaction in Chinese adults as measured by standard testing methods used in other human populations. In healthy Chinese subjects, gustation was normal and did not vary with age. Our data provide preliminary normative values for future investigation of chemosensation in the Chinese population.

Normative data for a solution-based taste test

The aim of our study was to study gustatory function in a large portion of the general population using liquid tastants, extending previous research. Further, we investigated the test-retest reliability of the test used. Data from 944 healthy subjects were used (498 women and 446 men, mean age 45 years; age range 5-90 years). For lateralized assessment of gustatory function, liquid taste solutions were used with different concentrations of each tastant (sweet 0.03, 0.1, 0.4, 2 g/mL sucrose solution; sour 0.01, 0.05, 0.1, 0.15 mL citric acid; salty 0.025, 0.075, 0.15, 0.36 mL sodium chloride solution; bitter 0.0002, 0.0005, 0.001, 0.01 mL quinine hydrochloride). A drop (approximately 20 µL) of liquid tastant was applied on the right side or on the left side of the anterior/posterior third of the extended tongue. The taste test had a good test-retest reliability r (304) = 0.78 (P < 0.001) for the total score and r (304) = 0.77 (P < 0.001) for the right-sided measures and r (304) = 0.75 (P < 0.001) for the left-sided measures, respectively. Gustatory sensitivity was found to decrease with age; women were more sensitive to gustatory stimuli than men. Irrespective of the sex-related differences, the total score at the 10th percentile was 28 in subjects younger than 15 years, 26.1 for ages from 16 to 35 years, 25 for ages from 36 to 55 years, and 24 for subjects older than 56 years of age. In conclusion, this test is recommended for clinical assessment of the ability to taste. The test provides reliable data, which is easy to handle, inexpensive, timesaving and can be self-made.