Disorders of Taste and Smell

The association between parameters of physical activity and olfactory function-the importance of frequency and moderate intensity

Introduction

Overall physical activity (PA) has been linked to decreased olfactory dysfunction and could improve olfactory function. Additionally, decreased olfactory function can contribute to reduced overall PA levels, given its association with neurodegenerative disorders. This study aims to examine the relationship between specific PA parameters (duration, frequency, intensity) and olfactory function in adults.

Methods

A total of 3,527 participants from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 underwent assessments for weekly PA duration, frequency, and intensity, alongside a smell test (including odors such as chocolate, strawberry, grape, onion, smoke, natural gas, leather, and soap). Correlation analyses and binary logistic regressions using SPSS were used to evaluate associations.

Results

The total smell score exhibited small yet significant positive correlations with the duration, frequency, and volume of moderate PA (correlation coefficients ranging between 0.05 and 0.08; all p ≤ 0.05) and frequency of vigorous PA (correlation coefficient of 0.05; p < 0.05). For moderate PA, the duration, frequency, and volume were significantly and positively associated with the ability to correctly detect the smell of grapes while the frequency was significantly and positively associated with the ability to identify smoke and leather odors (odds ratios ranging from 1.01 to 1.07; p < 0.05). For vigorous PA, the frequency of PA was positively associated with the detection of grape smell (odds ratio of 1.05; p < 0.05).

Conclusion

Some parameters of an active lifestyle are associated with improved odds of accurately identifying odors by up to 7.4%. Moderate PA duration, frequency, and volume were linked to better olfactory scores, while high-intensity PA had limited associations.

Oral symptoms potentially associated with mild-to-moderate COVID-19 in tobacco users

INTRODUCTION

Coronavirus disease (COVID-19) is a worldwide infection characterized by various symptoms. Few studies have examined its oral manifestations. However, there is insufficient information on the oral manifestations of patients with COVID-19 who use tobacco products. Therefore, this cross-sectional study investigated oral symptoms of tobacco-using patients with mild-to-moderate COVID-19.

METHODS

This study used a convenience sample of non-hospitalized patients (aged ≥18 years) with mild-to-moderate COVID-19 diagnosed by polymerized chain reaction (PCR). This study excluded pregnant or lactating women or patients with serious COVID-19 complications, including those who required hospitalization or were on specific medications (antiviral, corticosteroid, antimicrobial, or immunosuppressive). Oral examinations were performed, including labial, buccal, and gingival mucosa, tongue, floor of the mouth, and palate, for any newly developed lesions associated with the onset of COVID-19. The salivary flow was determined using the passive drool collection technique.

RESULTS

Lip dryness, gingivitis, tongue lesions, and taste loss were the most commonly reported oral symptoms in patients with mild-to-moderate COVID-19. The most common general symptoms were tiredness and headache (63.9%), followed by dry cough, myalgia, sore throat, and fever. This study found 139 occurrences of oral symptoms, of which 52 were dry lips (27 tobacco non-users, and 25 tobacco users), and 11 were gingivitis (five non-users, and six tobacco users), and 12 tongue changes (eight non-users, and four tobacco users). Ageusia, or loss of taste sensation, was most commonly reported with or without other oral COVID-19 symptoms (55 occurrences: 36 non-users and 19 tobacco users). No significant differences were found in oral symptoms between tobacco non-users and tobacco users.

CONCLUSIONS

There is a need to expand the routine examination protocol for patients during future respiratory pandemics, as monitoring oral health allows dentists to improve the management of oral sequelae during a pandemic.

Short Communication: Stellate Ganglion Blockade for Persistent Olfactory and Gustatory Symptoms Post-COVID-19

One hundred ninety-five patients presenting with post-COVID symptomology, including parosmia and dysgeusia, underwent reversible stellate ganglion blockade. Stellate ganglion blockade was performed at an outpatient facility, and patients were evaluated via survey at seven days post-injection. Of the 195 participants, ages ranged from 18-69 years of age with the breakdown of sexes being females n = 157 and males n = 38. The most significant finding was a reported improvement in olfaction post-injection in 87.4% of subjects. The effectiveness of this novel treatment for post-COVID is promising and warrants further investigation.

Localization of BDNF and Calretinin in Olfactory Epithelium and Taste Buds of Zebrafish (Danio rerio)

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family and it is involved in several fundamental functions in the central and peripheral nervous systems, and in sensory organs. BDNF regulates the chemosensory systems of mammals and is consistently expressed in those organs. In zebrafish, the key role of BDNF in the biology of the hair cells of the inner ear and lateral line system has recently been demonstrated. However, only some information is available about its occurrence in the olfactory epithelium, taste buds, and cutaneous isolated chemosensory cells. Therefore, this study was undertaken to analyze the involvement of BDNF in the chemosensory organs of zebrafish during the larval and adult stages. To identify cells displaying BDNF, we compared the cellular pattern of BDNF-displaying cells with those immunoreactive for calretinin and S100 protein. Our results demonstrate the localization of BDNF in the sensory part of the olfactory epithelium, mainly in the ciliated olfactory sensory neurons in larvae and adult zebrafish. Intense immunoreaction for BDNF was also observed in the chemosensory cells of oral and cutaneous taste buds. Moreover, a subpopulation of olfactory sensory neurons and chemosensory cells of olfactory rosette and taste bud, respectively, showed marked immunopositivity for calcium-binding protein S100 and calretinin. These results demonstrate the possible role of BDNF in the development and maintenance of olfactory sensory neurons and sensory cells in the olfactory epithelium and taste organs of zebrafish during all stages of development.

The druggability of bitter taste receptors for the treatment of neurodegenerative disorders

The delivery of therapeutic drugs to the brain remains a major pharmacology challenge. A complex system of chemical surveillance to protect the brain from endogenous and exogenous toxicants at brain barriers hinders the uptake of many compounds with significant in vitro and ex vivo therapeutic properties. Despite the advances in the field in recent years, the components of this system are not completely understood. Recently, a large group of chemo-sensing receptors, have been identified in the blood-cerebrospinal fluid barrier. Among these chemo-sensing receptors, bitter taste receptors (TAS2R) hold promise as potential drug targets, as many TAS2R bind compounds with recognized neuroprotective activity (quercetin, resveratrol, among others). Whether activation of TAS2R by their ligands contributes to their diverse biological actions described in other cells and tissues is still debatable. In this review, we discuss the potential role of TAS2R gene family as the mediators of the biological activity of their ligands for the treatment of central nervous system disorders and discuss their potential to counteract drug resistance by improving drug delivery to the brain.

Machine Learning Enhances the Performance of Bioreceptor-Free Biosensors

Since their inception, biosensors have frequently employed simple regression models to calculate analyte composition based on the biosensor's signal magnitude. Traditionally, bioreceptors provide excellent sensitivity and specificity to the biosensor. Increasingly, however, bioreceptor-free biosensors have been developed for a wide range of applications. Without a bioreceptor, maintaining strong specificity and a low limit of detection have become the major challenge. Machine learning (ML) has been introduced to improve the performance of these biosensors, effectively replacing the bioreceptor with modeling to gain specificity. Here, we present how ML has been used to enhance the performance of these bioreceptor-free biosensors. Particularly, we discuss how ML has been used for imaging, Enose and Etongue, and surface-enhanced Raman spectroscopy (SERS) biosensors. Notably, principal component analysis (PCA) combined with support vector machine (SVM) and various artificial neural network (ANN) algorithms have shown outstanding performance in a variety of tasks. We anticipate that ML will continue to improve the performance of bioreceptor-free biosensors, especially with the prospects of sharing trained models and cloud computing for mobile computation. To facilitate this, the biosensing community would benefit from increased contributions to open-access data repositories for biosensor data.

Barriers to effective health care for patients who have smell or taste disorders

Objectives

Smell/taste disturbances are a common but underrated, under‐researched and under treated sensory loss and an independent risk factor for reduced longevity. This study aimed to characterise the experience of patients with these disorders in seeking help.

Design

The study was designed by patients together with clinicians through a dedicated workshop and conducted as a cross‐sectional survey to capture experiences in public and private healthcare settings internationally.

Setting

Primary, secondary and tertiary care.

Participants

Any members of the public self‐reporting a smell/taste disorder were invited to participate.

Main outcome measures

The survey captured information including experience of getting consultations and referrals to medical professionals, treatments offered, costs incurred and related problems with mental health.

Results

Of 673 participants; 510 female, 160 male, three not stated, self‐reported aetiology included sinonasal disease (24%), idiopathic (24%) and post‐viral olfactory dysfunction (22%); true gustatory disorders were typically rare. Failure of medical professionals to recognise the problem was a key concern ‐ 64%, 76% and 47% of GPs, ENT specialists and Neurologists acknowledged, respectively. Other issues included repeated ineffective treatments, difficulties getting referrals to secondary/tertiary care, mental health problems (60%) and a mean personal cost of £421 to seeking advice and treatment. Whilst the participants were self‐selecting, however, they do represent those who are seeking help and intervention for their disorders.

Conclusion

There is an unmet need for these patients in accessing health care including a clear need to improve education of and engagement with the medical profession in Otorhinolaryngology, General Practice and other specialties, in order to remove the current barriers they face.

Neuromechanisms of SARS-CoV-2: A Review

Recent studies have suggested the neuroinvasive potential of severe acute respiratory coronavirus 2 (SARS-CoV-2). Notably, neuroinvasiveness might be involved in the pathophysiology of coronavirus disease 2019 (COVID-19). Some studies have demonstrated that synapse-connected routes may enable coronaviruses to access the central nervous system (CNS). However, evidence related to the presence of SARS-CoV-2 in the CNS, its direct impact on the CNS, and the contribution to symptoms suffered, remain sparse. Here, we review the current literature that indicates that SARS-CoV-2 can invade the nervous system. We also describe the neural circuits that are potentially affected by the virus and their possible role in the progress of COVID-19. In addition, we propose several strategies to understand, diagnose, and treat the neurological symptoms of COVID-19.

Appetite, Metabolism and Hormonal Regulation in Normal Ageing and Dementia

Feeding and nutrition follow the growth trajectory of the course of life. The profound physiological changes that human body experiences during ageing affect separate aspects of food intake, from tastant perception to satiety. Concurrent morbidities, such as neurodegeneration, as seen in dementia, and metabolic syndrome, may further shape nutritional behaviours, status and adequacy. In an effort to fill the gap between the exhausting basic research and the actual needs of professionals caring for the exponentially expanding ageing population, the current review addresses major factors relevant to appetite and eating disturbances. Does age alter the perception of food modalities? Is food generally still perceived as alluring and delicious with age? Is there an interplay between ageing, cognitive decline, and malnutrition? What tools can we adopt for proper and timely monitoring? Finally, what anatomical and pathophysiological evidence exists to support a hypothesis of central regulation of metabolic perturbations in normal and accelerated cognitive impairment, and how can we benefit from it in health practice?

A case of anosmia and hypogeusia as a complication of propofol

Anesthetics represent an uncommon cause of taste and smell disorders. We describe a case of anosmia and hypogeusia for 6 weeks after recovery from a uterine curettage operation in a 32-year-old woman. The case is unusual because propofol was the only anesthetic used during surgery and anesthesia. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed no abnormality. This case may highly suggest that propofol could induce smell and taste disorders.

Causality Assessment of Olfactory and Gustatory Dysfunction Associated with Intranasal Fluticasone Propionate: Application of the Bradford Hill Criteria

Causality assessment is crucial to post-marketing pharmacovigilance and helps optimize safe and appropriate use of medicines by patients in the real world. Self-reported olfactory and gustatory dysfunction are common in the general population as well as in patients with allergic rhinitis and nasal polyposis. Intranasal corticosteroids, including intranasal fluticasone propionate (INFP), are amongst the most effective drugs indicated in the treatment of allergic rhinitis and nasal polyposis. While intranasal corticosteroids are associated with olfactory and gustatory dysfunction and are currently labeled for these adverse events, causality assessment has not been performed to date. Although there is no single widely accepted method to assess causality in pharmacovigilance, the Bradford Hill criteria offer a robust and comprehensive approach because nine distinct aspects of an observed potential drug–event association are assessed. In this literature-based narrative review, Hill’s criteria were applied to determine causal inference between INFP and olfactory and gustatory dysfunction.