Taste and smell perception in the elderly: effect of medications and disease

A population study on factors associated with unintentional falls among Iranian older adults

INTRODUCTION

Falls among older adults are a significant cause of disability, injury, and death worldwide. The high incidence of falls in older adults, combined with the increased susceptibility to injury of the older adult population, leads to severe global health issues. Further studies are needed to comprehensively evaluate the typical personal and environmental risk factors of falls in the Iranian elderly population. Future preventive strategies and intervention programs will be based on these findings. The study determined the risk factors associated with unintentional falls among a representative sample of older adults living in Tehran, the capital city of Iran.

METHODS

The study design was cross-sectional. The target population was men/women aged 65 years and over from the general population living in 22 different districts of Tehran who were selected by stratified random sampling. The researchers gathered the data using validated questionnaires and observations. The informed consent was obtained from all participants before starting the interview. Multivariate logistic regression analysis examined the association between falls occurring during the past 12 months with demographics/ socioeconomics and fall-related predictor factors.

RESULTS

The risk of falls was higher in women (47.0%) and those aged ≥ 75 years (44.1%). Older adults who were married had their fall risk reduced by 36.4% compared with other types of marital status. Older adults who were illiterate (48.1%), housewives (47.0%), and always had concerns about living expenses (53.9%) tended significantly to have a higher risk of falls. Moreover, participants who live with their family were less likely to fall than those who live alone (36.5% vs. 40.4%). Persons with safe homes were less likely to experience falls than persons with unsafe homes (30.9% vs. 41.4%). The logistic regression analysis showed that the female gender, being worried about living expenses, home safety, functional behavior, and function factors, were independently associated with the risk of falls during the past 12 months.

CONCLUSIONS

Our findings revealed that a wide range of intrinsic and extrinsic risk factors contributed to injurious falls; based on the literature, some are preventable. The present data may be helpful as a starting point and guide future efforts for health providers and policymakers to allocate additional resources and develop proper falls prevention or intervention programs at the community level.

Partial Reversal of Anosmia Following Platinum-Based Chemotherapy in a Patient With Colorectal Adenocarcinoma

Platinum-based chemotherapy is known to cause taste and smell changes (TSCs) via a host of mechanisms, including altered receptor activity, saliva/mucus production, and induction of receptor destruction via mitotic inhibition. In the literature to date, these changes have primarily resulted in worsening of taste and smell. In this case report, we document the first instance of an individual regaining their sense of olfactory detection following treatment with oxaliplatin for colorectal adenocarcinoma. We theorize that the improvement in his sense of smell may have resulted from oxaliplatin-induced destruction of his nasal polyps through the caspase-9/procaspase-9 apoptotic pathway, a pathway shared with other mechanisms of nasal polyp destruction. These findings were supported by nasal endoscopy and sphenoid sinusoscopy, which demonstrated no clinical persistence of nasal polyps, in contrast to nasal endoscopy prior to chemotherapy which demonstrated persistent nasal polyposis. Objective smell testing post-treatment revealed a diminished ability to discriminate odors. Chemotherapy-induced TSCs play a key role in poor weight gain, food aversion, emotional distress, and an overall decrease in quality of life, and patients should be informed of these potential consequences prior to starting treatment. However, in patients with anosmia secondary to nasal polyposis, treatment with platinum-based chemotherapy may provide an additional therapeutic benefit. Further studies may help elucidate the potential therapeutic benefits of these agents in managing steroid-resistant polyposis for patients suffering from olfactory dysfunction.

Drug-induced olfactory and gustatory dysfunction: Analysis of FDA adverse events reporting system

OBJECTIVES

With the COVID-19 pandemic, there is growing interest and research in olfactory and gustatory dysfunction (OGD). Drug-induced dysfunction is an often overlooked etiology. While several medications include smell or taste disturbance as a side effect, there are no publications describing which medications are most frequently implicated. We aim to describe the patterns of these adverse drug reactions (ADRs) using the FDA Adverse Events Reporting System (FAERS).

METHODS

The FAERS database was queried from 2011 to 2021 for terms describing ADRs related to OGD. Terms included anosmia, hyposmia, olfactory test abnormal, olfactory nerve disorder, hallucination olfactory, parosmia, ageusia, hypogeusia, dysgeusia, and taste disorder. We identified the top reported medications associated with general smell dysfunction, general taste dysfunction, reduced smell, and altered smell.

RESULTS

From 2011 to 2021, 16,091 ADRs were reported with OGD, of which13,641 (84.8%) and 2,450 (15.2%) were associated with gustatory and olfactory reactions, respectively. Zinc products (370 reports) and fluticasone propionate (214) were most commonly associated with olfactory dysfunction, specifically reduced olfaction. Varenicline (24) and fluticasone propionate (23) were most commonly associated with altered smell. Lenalidomide (490) and sunitinib (468) were most commonly associated with gustatory dysfunction. Antineoplastic and immunomodulating medications accounted for 21.6% and 36.3% of olfactory and gustatory ADRs, respectively. Among this category, immunoglobulin drugs were the most commonly associated with OGD ADRs.

CONCLUSION

Gustatory dysfunction is more commonly reported ADR compared with olfactory dysfunction. Immunologic/rheumatologic medications are the leading culprit of reported OGD. With increasing numbers of patients presenting to otolaryngologists for OGD, it is important to consider drug-induced etiology.

LEVEL OF EVIDENCE

III.

The Influence of Nutritional Status and Sleep Quality on Gustatory Function in Older Adults

Background and Objectives: Age-related declines in taste function are common. Taste acuity can be affected by nutritional status and sleep quality. This research aims to examine the effect of nutritional status and sleep quality on gustatory function in community-dwelling older adults. Materials and Methods: This cross-sectional study included 119 community-dwelling older adults (50.4% of whom were female). The gustatory function was evaluated using four liquid taste solutions (sweet, bitter, sour, and salty) each at four different concentrations and the Mini Nutritional Assessment (MNA) and Pittsburgh Sleep Quality Index (PSQI) was applied. Additionally, anthropometric measurements were taken. Results: The mean scores on the gustatory test for the sweet, bitter, sour, and salty tastes were 2.11 ± 1.27, 2.12 ± 1.03, 2.28 ± 1.03, and 1.98 ± 1.41, respectively. There were significant differences according to gender, polypharmacy, nutritional status, and sleep quality in identifying sweet tastes (all p < 0.05). It was also found that females and participants without polypharmacy had better scores for bitter tastes. When the gustatory functions were evaluated according to BMI classification, it was determined that underweight participants had a higher sour taste score than the obese ones. Multiple regression analysis revealed that age, MNA score, PSQI score, and gender accounted for a total of 20.4% of the variance in the sweet taste score. Conclusions: Determining the relationship between taste function, nutritional status, and sleep quality in older adults is important in terms of developing new strategies for older adults who have these problems.

Significance of furosemide in patients with cirrhosis treated with or without zinc acetate hydrate supplementation

BACKGROUND

The Japanese guidelines for the treatment of cirrhosis suggest zinc supplementation to prevent hepatic encephalopathy in patients with cirrhosis and zinc deficiency, although the factors that are associated with therapeutic efficacy remain unknown.

METHOD

A total of 159 patients with chronic liver diseases but without previous zinc supplementation were analyzed. Factors associated with serum zinc levels as well as the therapeutic efficacy of zinc supplementation were evaluated.

RESULT

Serum zinc levels decreased with the progression of liver diseases. A multiple linear regression analysis revealed that the serum levels of albumin and cholinesterase and the daily furosemide dose were independently associated with the serum zinc levels. The optimal furosemide cut-off dosage for patients with zinc deficiency (<60 μg/dl) was 5 mg/day. Among 34 patients receiving zinc acetate hydrate, overt hepatic encephalopathy occurred in 12 patients (35.4%). A multivariate analysis identified a minimal serum zinc level of 50 μg/dl after more than 12 weeks of zinc supplementation as a factor associated with overt encephalopathy development, while furosemide use was not associated. The Child-Pugh score at baseline was the only factor associated with the maintenance of sufficient serum zinc levels.

CONCLUSION

Although the furosemide dose was negatively correlated with the serum zinc level in patients with chronic liver diseases, furosemide use was not associated with the occurrence of overt encephalopathy in those receiving zinc supplementation. Serum zinc levels of ≥50 μg/dl were required to prevent overt encephalopathy development during zinc supplementation in both patients with and those without furosemide administration.

Computational Analysis of Olfactory Airspace in Patients With Unilateral Cleft Lip Nasal Deformity

OBJECTIVES

To evaluate the magnitude of olfactory recess opacity in patients with unilateral cleft lip nasal deformity (uCLND).

DESIGN

Subject-specific 3-dimensional reconstruction of the nasal airway anatomy was created from computed tomography images in 11 (4 males and 7 females) subjects with uCLND and 7 (3 males, and 4 females) normal subjects. The volume and surface area of each subject's unilateral and bilateral olfactory airspace was quantified to assess the impact of opacification. Qualitatively speaking, patients with 75% to 100% olfactory recess opacification were classified as extreme, 50% to 75% as severe, 25% to 50% as moderate, and 0% to 25% as mild.

RESULTS

Of the 11 subjects with uCLND, 5 (45%) were classified as having extreme olfactory recess opacification, 3 (27%) subjects had severe opacification, and 3 (27%) subjects had moderate opacification. Mean (±SD) bilateral olfactory recess volume was significantly greater in normal subjects than in subjects with uCLND (0.9668 cm³ ± 0.4061 cm³ vs 0.3426 cm³ ± 0.1316 cm³; P < .001). Furthermore, unilateral olfactory airspace volumes for the cleft and non-cleft sides in subjects with uCLND were considerably less than unilateral olfactory volume in subjects with normal anatomy (uCLND cleft side = 0.1623 cm³ ± 0.0933 cm³; uCLND non-cleft side = 0.1803 cm³ ± 0.0938 cm³; normal = 0.4834 cm³ ± 0.2328 cm³; P < .001).

CONCLUSIONS

Our findings indicate a high prevalence of olfactory recess opacification among subjects with uCLND when compared to subjects with normal anatomy. The majority of subjects with uCLND had extreme olfactory recess opacity, which will likely influence their sense of smell.

Identification of aroma compounds in a commonly prescribed oral nutritional supplement and associated changes in olfactory abilities with human ageing

Undernutrition is prevalent in the older adult population. Oral nutritional supplements (ONS) are a clinically effective nutritional intervention, however, patient acceptance of ONS can be limited by their palatability. While sensory attributes such as sweetness and mouthfeel have been investigated, the contribution made by aroma to the perceived flavour of ONS has not been studied. Firstly, this research aimed to identify the aroma active compounds within a commonly prescribed ONS using estimated odour activity values (OAV) and gas chromatography olfactometry mass spectrometry (GC-O-MS). Secondly, age related differences in olfactory detection were explored. Eight aroma active compounds were identified within the ONS, including diacetyl (sweet), isoamyl acetate (banana), dimethyl trisulfide (sulfur) and methanethiol (sulfur). When compared with younger adults (n = 24, 18–44 years), older adults (n = 24, 62–80 years) had higher detection thresholds for all aroma compounds and this was significant for isoamyl acetate (sweet, fruity) and methanethiol (sulfur) (p = 0.01 and p = 0.03, respectively). Thus, a decline in olfactory sensitivity was present in the older subjects included in the study, and this reduced detection sensitivity was aroma specific. Thus, older adults’ flavour perception of ONS likely depends on the combined effect of product factors (the aroma profile) along with age related consumer factors (the degree of impairment in perception). This is a fundamental study which will aid future research into how the aroma profile, and associated age related impairments in perception, shape the global perception of ONS for nutritionally at risk older individuals.

Age group determines the acceptability of protein derived off-flavour

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Heat-treatment of protein ingredients can impart sulfurous flavours into beverages.

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Sulfurous flavours negatively impacted consumer acceptance of a dairy beverage.

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Older adults had greater acceptance of sulfurous flavours compared to younger adults.

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Diacetyl reduced the negative impact of these compounds for both age groups.

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Best estimate thresholds give a conservative estimate of off-flavour acceptability.

Many older adults fail to meet their daily protein requirements, potentially due to social, physical and medical factors, including sensory and appetite changes. Additionally, our previous research has identified potential sulfurous off-flavours, originating from heat-treatment of protein ingredients, which could play a role in consumer acceptance. This study aims to determine the hedonic impact of these potential off-flavours when added to a dairy beverage, identify the specific off-flavour concentrations which cause rejection by consumers, and lastly investigate difference in acceptance between older and younger consumers. A rejection threshold (RjT) protocol was used, in combination with Best Estimate Thresholds (BET), whereby sulfurous flavours (dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide), and diacetyl were added to create a range of concentrations. 95 participants (younger n = 49, 18–38 years; older n = 46, 60–79 years) tasted 7 pairs of samples (one blank and one with ascending off-flavour concentration) and selected their preferred samples. Sulfurous flavours negatively impacted consumer acceptance, however, the extent to which they impart a negative effect differs between age groups. Younger adults rejected samples containing low concentrations of sulfurous off-flavours (1.55 ppb), however, older adults rejected samples with concentrations over 3 times higher (5.08 ppb). When combined with sulfurous flavours, diacetyl increased the rejection threshold for both groups. In conclusion, these observations imply that a greater quantity of off-flavour may be present before acceptance is reduced in the older consumer group. Moreover, diacetyl demonstrates partial masking abilities of sulfurous off-flavours, and BET gave a more conservative estimate of acceptability. This knowledge will help guide sensory innovation of high-protein beverages for older consumers to support product acceptance and optimal intake.

Presence of gustatory and olfactory dysfunction in the time of the COVID-19 pandemic

BACKGROUND

The unexpected outbreak of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused more than 49 million cases and an estimated 2,000,000 associated deaths worldwide. In Germany, there are currently more than 2,000,000 laboratory-confirmed coronavirus disease 2019 (COVID-19) cases including 51,800 deaths. However, regional differences also became apparent and with the second wave of infections, the detailed characterization of COVID-19 patients is crucial to early diagnosis and disruption of chains of infections.

METHODS

Handing out detailed questionnaires to all individuals tested for COVID-19, we evaluated the clinical characteristics of negative and positive tested individuals. Expression of symptoms, symptom duration and association between predictor variables (i.e. age, gender) and a binary outcome (olfactory and gustatory dysfunction) were assessed.

RESULTS

Overall, the most common symptoms among individuals who tested positive for SARS-CoV-2 were fatigue, headache, and cough. Olfactory and gustatory dysfunction were also reported by many SARS-CoV-2 negative individuals, more than 20% of SARS-CoV-2 negative tested individuals in our study reported olfactory and gustatory dysfunction. Independent of SARS-CoV-2 status, more females displayed symptoms of gustatory (29.8%, p = 0.0041) and olfactory dysfunction (22.9%, p = 0.0174) compared to men.

CONCLUSIONS

Bringing early SARS-CoV-2 tests to the populations at risk must be a main focus for the upcoming months. The reliability of olfactory and gustatory dysfunction in COVID-19 negative tested individuals requires deeper investigation in the future.

Taste Sensitivity of Elderly People Is Associated with Quality of Life and Inadequate Dietary Intake

Aging has been implicated in the alteration of taste acuity. Diet can affect taste sensitivity. We aimed to investigate the types of tastes altered in elderly Korean people and factors associated with taste alteration in relation to dietary intake and other factors. Elderly participants (≥65 years) and young adults were assessed to determine their recognition thresholds (RT) for sweet, salty, bitter, sour, and umami tastes. Elderly participants were further surveyed for dietary intake and non-nutritional factors. Five taste RTs were correlated with age, but only four taste RTs, except sweetness, differed between the elderly participants and young adults. Inadequate intake of iron, thiamin, folic acid, zinc, and phosphorus among the elderly participants was related to elevated taste RT levels, except for bitter taste. In both correlation and regression analyses, only salty and sour RTs were associated with energy, iron, thiamin, fiber, vitamin C, and riboflavin levels in the elderly participants. The elderly participants’ taste RTs exhibited strong associations with quality of life (QOL) but showed partial relationships with physical activity, number of medicine intakes, social gatherings, and education. Taste sensitivity may decrease with age, which is further influenced by insufficient dietary intake, especially iron and thiamin, and QOL.

Olfaction and Aging: A Review of the Current State of Research and Future Directions

Olfaction, the sense of smell, is characterized by a notable age-dependency such that aging individuals are more likely to have poor olfactory abilities. These impairments are considered to be mostly irreversible and as having potentially profound effects on quality of life and food behavior, as well as constituting warning signs of mortality, cognitive dysfunction, and dementia. Here, we review the current state of research on aging and olfaction, focusing on five topics which we regard to be of particular relevance for the field: nutrition and health, cognition and dementia, mortality, environment and genetics, and training-based enhancement. Under each of these headlines, we provide a state-of-the-art overview and discuss gaps in our knowledge which might be filled by further research. Understanding how olfactory abilities are diminished in aging, and how they may be alleviated or recovered, involves a set of challenging tasks for researchers in the years to come.

Molecular and Genetic Factors Involved in Olfactory and Gustatory Deficits and Associations with Microbiota in Parkinson's Disease

Deficits in olfaction and taste are among the most frequent non-motor manifestations in Parkinson’s disease (PD) that start very early and frequently precede the PD motor symptoms. The limited data available suggest that the basis of the olfactory and gustatory dysfunction related to PD are likely multifactorial and may include the same determinants responsible for other non-motor symptoms of PD. This review describes the most relevant molecular and genetic factors involved in the PD-related smell and taste impairments, and their associations with the microbiota, which also may represent risk factors associated with the disease.

Influence of Age and Individual Differences on Mouthfeel Perception of Whey Protein-Fortified Products: A Review

Protein needs are considered to increase with age, with protein consumption being associated with many positive outcomes. Protein-fortified products are often used to improve nutritional status and prevent age-related muscle mass loss in older adults. Accordingly, older adults are commonly provided with products fortified with whey protein; however, such products can cause mouthdrying, limiting consumption and product enjoyment. Currently, the extent to which age and individual differences (e.g., saliva, oral health, food oral processing) influence the perception of whey protein-derived mouthdrying is relatively unclear. Previous research in this area has mainly focused on investigating mouthdrying, without taking into account individual differences that could influence this perception within the target population. Therefore, the main focus of this review is to provide an overview of the relevant individual differences likely to influence mouthfeel perception (specifically mouthdrying) from whey protein-fortified products, thereby enabling the future design of such products to incorporate better the needs of older adults and improve their nutritional status. This review concludes that age and individual differences are likely to influence mouthdrying sensations from whey protein-fortified products. Future research should focus more on the target population and individual differences to maximise the benefits from whey protein fortification.

Saliva NMR-Based Metabolomics in the War Against COVID-19

COVID-19 is an emergent, worldwide public health concern. Joint efforts have been made by scientific communities of various fields to better understand the mechanisms of action of SARS-CoV-2. The need to understand the pathophysiological fingerprint and pathways of this disease make metabolomics-related approaches an indispensable tool for properly answering concerns relating to disease course. Determination of the metabolomic profile may help to explain the heterogeneous spectra of COVID-19 clinical phenotypes and be useful in monitoring disease progression as well as therapeutic treatments. In this sense, saliva has proven to be a strategic biofluid, owing not only to its appeal as a noninvasive sampling method but also due to the capacity of the virus to invade epithelial cells of the oral mucosa and salivary gland ducts via ACE2 receptors. Accordingly, important changes in metabolism have been described relating to COVID-19, indicating that metabolomics may open new avenues for understanding the pathophysiology of this disease, especially via longitudinal study designs. Thus, we discuss the importance of comprehending the SARS-CoV-2 salivary metabolomic fingerprint and also highlight the situation of Brazil on the frontlines of the war against COVID-19.

[Normal sensory aging]

Normal aging can be defined as the result of the effects of genetic and environmental factors to which subjects are exposed throughout their lives. This process is slow and progressive and must be distinguished from disease. All organs are subject to aging in a physiological way.

Influence of medications on taste and smell

Medications frequently have chemosensory side effects that can adversely affect compliance with medical treatment regimens. Hundreds of drugs have been reported to induce unpleasant tastes and/or odors as well as altered chemosensations when administered alone or in combination with other medications. Some chemosensory complaints are due to the sensory properties of the drug itself such as aversive bitter and metallic tastes. However, most chemosensory side effects of drugs are due to alterations in the transduction pathways, biochemical targets, enzymes, and transporters by the offending medications. Studies of chemosensory perception in medicated older individuals have found that taste and smell loss is greatest for those consuming the largest number of prescription drugs. There are no standard treatments for drug-induced chemosensory disorders because each drug has unique biological effects. However, there are a few treatment options to ameliorate chemosensory alterations including addition of simulated flavors to food to compensate for losses and to override offending tastes and smells.

Impact of medication on protein and amino acid metabolism in the elderly: the sulfur amino acid and paracetamol case

The optimisation of nutritional support for the growing number of older individuals does not usually take into account medication. Paracetamol (acetaminophen; APAP) is the first intention treatment of chronic pain that is highly prevalent and persistent in the elderly. Detoxification of APAP occurs in the liver and utilises sulfate and glutathione (GSH), both of which are issued from cysteine (Cys), a conditionally indispensable amino acid. The detoxification-induced siphoning of Cys could reduce the availability of Cys for skeletal muscle. Consequently, APAP could worsen sarcopenia, an important component of the frailty syndrome leading to dependency. The present review provides the rationale for the potential pro-sarcopenic effect of APAP then recent results concerning the effect of chronic APAP treatment on muscle mass and metabolism are discussed. The principal findings are that chronic treatments with doses of APAP comparable with the maximum posology for humans can increase the requirement for sulfur amino acids (SAA), reduce Cys availability for muscle, reduce muscle protein synthesis and aggravate sarcopenia in animals. One clinical study is in favour of an enhanced SAA requirement in the older individual under chronic treatment with APAP. Few clinical studies investigated the effect of chronic treatment with APAP combined with exercise, in nutritional conditions that probably did not affect Cys and GSH homeostasis. Whether APAP can aggravate sarcopenia in older individuals with low protein intake remains to be tested. If true, nutritional strategies based on enhancing Cys supply could be of prime interest to cut down the pro-sarcopenic effect of chronic treatment with APAP.

Prevalence and risk factors of taste and smell impairment in a nationwide representative sample of the US population: a cross-sectional study

OBJECTIVES

To estimate the prevalence of, and explore potential risk factors for, taste and smell dysfunction in the general population of the USA.

DESIGN

A cross-sectional study.

SETTING

A cross-sectional analysis of data collected in the National Health and Nutrition Examination Survey (NHANES 2013-2014).

PARTICIPANTS

A total of 3519 men and women aged 40 years and older who participated in NHANES 2013-2014.

MAIN OUTCOME MEASURES

Using the NHANES Pocket Smell Test, smell impairment was defined as failing to correctly identify 6 or more of the 8 odours. Taste impairment was defined as failing to correctly identify quinine or sodium chloride.

RESULTS

The estimated prevalence was 13.5% for smell impairment, 17.3% for taste impairment and 2.2% for taste and smell impairment. For smell, but not taste, prevalence estimates increased with age and were higher in men and ethnic minorities. In backward stepwise logistic regression, low educational attainment, low family income and a history of asthma or cancer were independently associated with a higher prevalence of smell impairment, whereas light-to-moderate alcohol consumption (1-3 drinks/day) was associated with a lower prevalence of this condition. After multivariate adjustment, being non-Hispanic Black Americans, consuming ≥4 drinks of alcohol per day and having a history of cardiovascular disease (CVD) were independently associated with a higher prevalence of taste impairment.

CONCLUSIONS

Based on a nationally representative multistage probability survey among the US population aged 40 years and older, smell and taste dysfunction affected ∼20.5 million (13.5%) and 26.3 million (17.3%) individuals, respectively. Age, gender, ethnicity, educational attainment, family income, light-to-moderate alcohol consumption and history of asthma or cancer were significant risk factors for smell dysfunction, whereas only ethnicity, heavy alcohol consumption and CVD history were associated with a higher prevalence of taste dysfunction.

Development and Validation of a Food-Associated Olfactory Test (FAOT)

Olfactory tests are an important tool in human nutritional research for studying food preferences, yet comprehensive tests dedicated solely to food odors are currently lacking. Therefore, within this study, an innovative food-associated olfactory test (FAOT) system was developed. The FAOT comprises 16 odorant pens that contain representative food odors relating to different macronutrient classes. The test underwent a sensory validation based on identification rate, intensity, hedonic value, and food association scores. The accuracy of the test was further compared to the accuracy of the established Sniffin' Sticks identification test. The identification rates and intensities of this new FAOT were found to be comparable to the Sniffin' Sticks olfactory identification test. The odorant pens were also assessed chemo-analytically and were found to be chemically stable for at least 24 weeks. Overall, this new identification test for use in assessing olfaction in a food-associated context is valid both in terms of its use in sensory perception studies and its chemical stability. The FOAT is particularly suited to examinations of the sense of smell regarding food odors.

Flavor perception test: evaluation in patients with Kallmann syndrome

In Kallmann syndrome (KS), congenital hypogonadism is associated with olfactory impairment. To evaluate flavor perception-related disability in KS patients, 30 patients with KS, 12 with normosmic hypogonadism (nIHH), 24 with acquired anosmia (AA), and 58 healthy controls entered the study. All participants completed questionnaires concerning dietary habits, olfaction-related quality of life (QoL), and self-determined olfactory, flavor, and taste abilities prior to undergoing standardized olfactometry and gustometry. Each subject underwent flavor testing, using orally administered aqueous aromatic solutions, identifying 21 different compounds by choosing each out of 5 alternative items. Flavor score (FS) was calculated as the sum of correct answers (range 0-21). Flavor perception by self-assessment was similar between KS, nIHH, and controls, and was mostly reduced only in AA. FS was similar between KS (5.4 ± 1.4) and AA (6.4 ± 1.9), and lower than in nIHH (16.2 ± 2.4, p < 0.001) and controls (16.8 ± 1.7, p < 0.0001). FS showed strong reproducibility, and correlated with olfactory scores in the overall population. KS and AA patients identified aromatics eliciting trigeminal stimulation better than pure odorants. Olfaction-related QoL was more impaired in AA than in KS. We report significant flavor impairment in KS. This contrasts with routine clinic evidence; KS patients, in contrast with AA, do not complain of flavor perception impairment, perhaps owing to the congenital nature of the dysfunction. Flavor perception impairment should be considered a specific KS disability, because of important detrimental effects on physical and mental health and on QoL. KS patients should also be advised of this impairment in order to prevent accidental and life-threatening events.

Inflammatory stimuli acutely modulate peripheral taste function

Inflammation-mediated changes in taste perception can affect health outcomes in patients, but little is known about the underlying mechanisms. In the present work, we hypothesized that proinflammatory cytokines directly modulate Na(+) transport in taste buds. To test this, we measured acute changes in Na(+) flux in polarized fungiform taste buds loaded with a Na(+) indicator dye. IL-1β elicited an amiloride-sensitive increase in Na(+) transport in taste buds. In contrast, TNF-α dramatically and reversibly decreased Na(+) flux in polarized taste buds via amiloride-sensitive and amiloride-insensitive Na(+) transport systems. The speed and partial amiloride sensitivity of these changes in Na(+) flux indicate that IL-1β and TNF-α modulate epithelial Na(+) channel (ENaC) function. A portion of the TNF-mediated decrease in Na(+) flux is also blocked by the TRPV1 antagonist capsazepine, although TNF-α further reduced Na(+) transport independently of both amiloride and capsazepine. We also assessed taste function in vivo in a model of infection and inflammation that elevates these and additional cytokines. In rats administered systemic lipopolysaccharide (LPS), CT responses to Na(+) were significantly elevated between 1 and 2 h after LPS treatment. Low, normally preferred concentrations of NaCl and sodium acetate elicited high response magnitudes. Consistent with this outcome, codelivery of IL-1β and TNF-α enhanced Na(+) flux in polarized taste buds. These results demonstrate that inflammation elicits swift changes in Na(+) taste function, which may limit salt consumption during illness.

Olfactory drug effects approached from human-derived data

The complexity of the sense of smell makes adverse olfactory effects of drugs highly likely, which can impact a patient's quality of life. Here, we present a bioinformatics approach that identifies drugs with potential olfactory effects by connecting drug target expression patterns in human olfactory tissue with drug-related information and the underlying molecular drug targets taken from publically available databases. We identified 71 drugs with listed olfactory effects and 147 different targets. Taking the target-based approach further, we found additional drugs with potential olfactory effects, including 152 different substances interacting with genes expressed in the human olfactory bulb. Our proposed bioinformatics approach provides plausible hypotheses about mechanistic drug effects for drug discovery and repurposing and, thus, would be appropriate for use during drug development.

Nutrition rehabilitation in the intensive care unit

The maintenance of homeostasis after severe injury requires the restoration of the physiological regulation of food intake. A wide array of functional alterations can hinder the intake of adequate amounts of nutrients to support the recovery from critical illness. These alterations encompass changes in the preprandial phase, reflected by a loss of appetite; changes in the prandial phase, yielding swallowing disorders; and changes in the postprandial phase, including impairments of gastric emptying, gut motility, and satiety. This tutorial aims to review these often overlooked features and to suggest recommendations for the nutrition rehabilitation of the critically ill.

Age and strength influences on lingual tactile acuity

Sensory function during the oral processing of liquids is thought to play a key role in informing the tailoring of swallowing motor behaviours to the flow characteristics of the bolus. In addition to taste receptors, the mouth and tongue house trigeminal nerve receptors that support the sensory detection of bolus size, shape (stereognosis), mass, temperature and movement. Recent studies suggest that healthy adults lose tongue strength with advancing age. However, little is known about changes in the sensory function of the tongue attributable to age, or associated with reductions in strength. In this study, we explored lingual tactile acuity in healthy young and older adults, and measured the relationship between tactile acuity and measures of tongue strength. The results showed an age-related reduction in lingual tactile acuity that was not explained by variations in tongue strength.

PRACTICAL APPLICATIONS

Sensory motor interactions are a topic of interest in understanding the processing activities that take place in the mouth during eating and swallowing. In this paper, we explore a test of sensory acuity in the mouth, in which the tongue is used to "read" embossed letters on Teflon strips. Our questions were to determine whether sensory acuity for this task declines with age, or with age-related reductions in tongue strength. We determined that older people perform this task with less accuracy, suggesting some changes in oral sensory function with age. However, these changes were not related to tongue strength. The findings suggest that strength does not play a major role in the kind of sensory discrimination task tested in this study.

The influences of age on olfaction: a review

Decreased olfactory function is very common in the older population, being present in over half of those between the ages of 65 and 80 years and in over three quarters of those over the age of 80 years. Such dysfunction significantly influences physical well-being and quality of life, nutrition, the enjoyment of food, as well as everyday safety. Indeed a disproportionate number of the elderly die in accident gas poisonings each year. As described in this review, multiple factors contribute to such age-related loss, including altered nasal engorgement, increased propensity for nasal disease, cumulative damage to the olfactory epithelium from viral and other environmental insults, decrements in mucosal metabolizing enzymes, ossification of cribriform plate foramina, loss of selectivity of receptor cells to odorants, changes in neurotransmitter and neuromodulator systems, and neuronal expression of aberrant proteins associated with neurodegenerative disease. It is now well established that decreased smell loss can be an early sign of such neurodegenerative diseases as Alzheimer's disease and sporadic Parkinson's disease. In this review we provide an overview of the anatomy and physiology of the aging olfactory system, how this system is clinically evaluated, and the multiple pathophysiological factors that are associated with its dysfunction.

Olfactory function and malnutrition in geriatric patients

BACKGROUND

Impaired olfaction is considered to be a risk factor for malnutrition in older adults; however, there is little research on this association. The aim of this study was to investigate whether olfactory deficits are associated with an impaired nutritional status in older patients.

METHODS

Study participants were recruited from a geriatric day hospital. Nutritional status was assessed with body mass index and Mini-Nutritional Assessment. Olfactory function was evaluated with the Sniffin' Sticks test (SST) and subjectively rated by the patient. Self-caring capacity was rated with the Barthel Index and cognitive status with the Mini-Mental State Examination.

RESULTS

One hundred ninety-one patients, 71.7% female, were included with a mean age of 79.6 ± 6.3 years. Prevalence of hyposmia was 39.3%, and 31.9% of patients were functionally anosmic. Malnourished patients did not have a significantly lower Sniffin' Sticks test score than patients at nutritional risk or malnourished patients. In linear regression analysis, nutritional status was only influenced by Barthel Index, age, and number of drugs but not by olfactory function.

CONCLUSION

In this sample, olfactory function was not associated with nutritional status.

Taste loss in hospitalized multimorbid elderly subjects

BACKGROUND

Loss of the sense of taste is common among older people. Morbidities and polypharmacy may contribute to the age-related decline in gustatory function. The aims of the present study were to investigate taste perception in elderly hospitalized patients by comparing their taste recognition thresholds with those of healthy, free-living elderly individuals and to identify potential determinants of taste loss.

METHODS

The participants in this observational study were 55 elderly patients hospitalized in the acute geriatric section of the Department of Medical and Surgical Sciences at Padova University and 41 free-living individuals aged older than 65 years, randomly recruited from elderly people attending mild fitness programs at public gymnasiums in Padova. Data were collected on nutrition, health, cognitive, and functional status for all participants. Gustatory capabilities were assessed using aqueous solutions of sucrose, sodium chloride, citric acid, and quinine hydrochloride (representing sweet, salty, sour, and bitter stimuli, respectively), and taste recognition thresholds were measured in both groups.

RESULTS

In comparison with the free-living elderly subjects, those in hospital were significantly less able to recognize the taste of citric acid (P < 0.05). Low citric acid sensitivity was independently associated with advanced age (≥75 years; odds ratio [OR] 3.01, 95% confidence interval [CI] 1.01-9.82), polypharmacy (number of prescribed drugs ≥ 4; OR 2.74, 95% CI 1.01-7.72), and poor nutritional status (as assessed by Mini Nutritional Assessment score < 23.5; OR 5.08, 95% CI 1.76-14.6).

CONCLUSION

Because gustatory impairment may reduce a person's appetite and lead to inadequate dietary intake, compensatory nutritional measures, such as the use of flavor-enhanced foods, should be strongly encouraged, particularly in the hospital setting.

Coming to your senses: detecting taste and smell alterations in chemotherapy patients. A systematic review

CONTEXT

Taste alterations (TAs) and smell alterations (SAs) are frequently observed, yet understudied side effects in chemotherapy patients, considerably affecting patients' quality of life.

OBJECTIVES

This review provides a systematic evaluation of the literature on TAs and SAs in cancer chemotherapy patients and discloses understudied research questions.

METHODS

A systematic methodology based on the PRISMA guidelines was applied to identify original research articles with TAs and SAs as primary outcomes in chemotherapy patients. MEDLINE and Embase were searched using Medical Subject Heading and free-text terms. Study extraction and evaluation were done by three reviewers using predefined criteria.

RESULTS

The search revealed 22 eligible studies, including three randomized controlled trials. Different measurement approaches were identified, with a clear trend toward self-report measures during the past decade. The methodological quality of the included studies varied, especially reports on SAs, which were inconsistent and hard to interpret. Regarding TAs, there is evidence that taste thresholds increase during chemotherapy. Qualitative changes, for example, metallic taste, are frequent but cannot be attributed to specific chemotherapy regimens. There are large research gaps regarding TAs and SAs in different patient populations and the impact of different chemotherapy regimens. Adequate management strategies are rare.

CONCLUSION

Current research results do not allow firm conclusions concerning the occurrence, severity, and quality of TAs and SAs under different chemotherapy regimens. Patient information on TAs and SAs, therefore, largely is based on the clinician's experience. In the palliative care setting, TAs and SAs need further investigation in the light of their importance in preventing food-related problems and maintaining a reasonable quality of life.

Taste alterations in cancer patients receiving chemotherapy: a neglected side effect?

BACKGROUND

Taste alterations (TAs) are a frequent but under-recognized treatment side effect in cancer patients undergoing chemotherapy (CT). CT regimens with different toxicity profiles may vary in their impact on TAs, but research on this topic is lacking. This study assesses the prevalence of TAs and their relation to sociodemographic and clinical variables, especially CT regimens. Furthermore, the association between TAs and quality of life (QOL) is investigated.

PATIENTS AND METHODS

TAs and QOL data were collected longitudinally in 197 cancer patients (lung cancer, 54.3%; pancreatic cancer, 19.3%; colorectal cancer, 26.4%; age, 65.2 +/-10.4 years; male, 57.4%) who were receiving CT at the Department of Internal Medicine at Kufstein County Hospital, giving rise to a total of 1,024 assessment times. Patients completed the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire and two additional questions taken from the EORTC item bank concerning TAs. Statistical analyses were performed using mixed-effect models.

RESULTS

The study showed that the prevalence of TAs in chemotherapy patients is alarmingly high (69.9%). There were clear differences in TA scores among treatment groups: patients receiving irinotecan reported significantly more TAs than patients in other treatment groups; patients receiving a combination of gemcitabine and a platinum agent reported the lowest TAs. Additionally, significant associations between TAs and several QOL dimensions were found, especially with appetite loss and fatigue.

CONCLUSION

The high prevalence of TAs and their impact on QOL in CT patients underscore the urgent need for increased attention to this side effect, both in research and in clinical practice.

Sour ageusia in two individuals implicates ion channels of the ASIC and PKD families in human sour taste perception at the anterior tongue

BACKGROUND

The perception of sour taste in humans is incompletely understood at the receptor cell level. We report here on two patients with an acquired sour ageusia. Each patient was unresponsive to sour stimuli, but both showed normal responses to bitter, sweet, and salty stimuli.

METHODS AND FINDINGS

Lingual fungiform papillae, containing taste cells, were obtained by biopsy from the two patients, and from three sour-normal individuals, and analyzed by RT-PCR. The following transcripts were undetectable in the patients, even after 50 cycles of amplification, but readily detectable in the sour-normal subjects: acid sensing ion channels (ASICs) 1a, 1beta, 2a, 2b, and 3; and polycystic kidney disease (PKD) channels PKD1L3 and PKD2L1. Patients and sour-normals expressed the taste-related phospholipase C-beta2, the delta-subunit of epithelial sodium channel (ENaC) and the bitter receptor T2R14, as well as beta-actin. Genomic analysis of one patient, using buccal tissue, did not show absence of the genes for ASIC1a and PKD2L1. Immunohistochemistry of fungiform papillae from sour-normal subjects revealed labeling of taste bud cells by antibodies to ASICs 1a and 1beta, PKD2L1, phospholipase C-beta2, and delta-ENaC. An antibody to PKD1L3 labeled tissue outside taste bud cells.

CONCLUSIONS

These data suggest a role for ASICs and PKDs in human sour perception. This is the first report of sour ageusia in humans, and the very existence of such individuals ("natural knockouts") suggests a cell lineage for sour that is independent of the other taste modalities.

Effects of aging on the human taste system

Losses in taste perception as well as distortions of gustatory function occur with greater frequency in older individuals, and these changes are exacerbated by certain medical conditions, pharmacologic interventions, radiation, and exposure to toxic chemicals. Medications, especially drug-drug interactions, are the most significant yet underappreciated contributors to taste disorders in the elderly. Taste disorders frequently occur when the fraction of an orally administered drug dose that reaches the systemic circulation is markedly increased due to inhibition (by a coadministered drug) of the efflux transporter P-glycoprotein and/or inhibition of the cytochrome P450 metabolism system, which normally limit systemic availability of drugs. The supratherapeutic plasma drug concentrations that result from drug-drug interactions can induce a taste from the blood side of taste cells (intravascular taste), alter taste cell biochemistry, and/or modify other aspects of the taste pathways.

Test-retest reliability of the San Diego Odor Identification Test and comparison with the brief smell identification test

This study described the San Diego Odor Identification Test (SDOIT) reliability and compared the SDOIT and the Brief Smell Identification Test (B-SIT). Ninety participants aged 50-70 years completed this 2-visit olfaction study. During visit 1, the SDOIT and B-SIT were administered according to standard protocols. Three weeks later, participants returned to retake the SDOIT. The SDOIT score was the total number of odorants correctly identified out of 8 odorants presented, and olfactory impairment was defined as correctly identifying less than 6 odorants. The B-SIT score was the total number of odorants correctly identified out of 12 odorants presented, and participants correctly identifying less than 9 odorants were categorized as abnormal. The SDOIT reliability was high (concordance correlation coefficient = 0.85, 95% confidence interval [CI] = 0.79-0.91). The same score was obtained on retest for 73% of participants, whereas 18% improved, and 9% declined. Test-retest agreement was 96% for the SDOIT; 4% improved from impaired at visit 1 to unimpaired at visit 2. Overall, SDOIT impairment classification and B-SIT abnormal classification agreed in 96% of participants (kappa = 0.81, 95% CI = 0.63-0.99). In conclusion, the SDOIT showed good test-retest reliability. Agreement for impaired/abnormal olfaction was demonstrated for the SDOIT and the B-SIT.

Changes of oral trigeminal sensitivity in patients after middle ear surgery

OBJECTIVES

The specific aim of this study was to re-investigate the effect of chorda tympani damage on both trigeminal sensitivity and taste ability.

STUDY DESIGN

Prospective study.

METHODS

Capsaicin-impregnated filter paper strips (5 concentrations, 0.0001-1%) were used to measure trigeminal thresholds. The strips were placed on the anterior tongue for 10 seconds. Thresholds were estimated in two ways: 1) thresholds related to sensory perception and 2) intensity-related thresholds. The test was applied to 29 patients who underwent middle ear surgery (mean age, 49 yr; 16 females, 13 males). Results were compared with those of 63 healthy subjects (mean age, 40 yr; 36 females, 29 males). In addition to trigeminal thresholds, measures of gustatory function were also obtained using both the validated "taste strips" test kit and electrogustometry.

RESULTS

For lateralized testing with capsaicin, significant differences were found between preoperative and postoperative thresholds and between the operated and nonoperated side, with thresholds being higher postoperatively on the operated side. The sensation-related thresholds from the operated tongue side exhibited a correlation with the corresponding postoperative electrogustometric thresholds. A higher degree of chorda manipulation was associated with higher postoperative capsaicin thresholds at the operated tongue side.

CONCLUSION

Pain-related sensitivity of the tongue decreases after middle ear surgery, indicating that chorda tympani function also influences intraoral trigeminal sensitivity.

Critical illness and changes in sensory perception

Impairments of sensory perception that occur during a period of critical care can seriously impact on health and nutritional status, activities of daily living, independence, quality of life and the possibility of recovery. It is emphasized from the outset that sensory losses in critically-ill patients may or may not be related to their current medical condition. The present paper provides an overview of all five senses (vision, hearing, taste, smell and touch) and describes the factors that contribute to sensory losses in critically-ill patients, including medications, medical conditions and treatments and the process of aging itself. Cancer and stroke are two critical illnesses in which profound sensory decrements often occur. Many sensory complaints in patients with cancer are related to alteration in sensory signals caused by damage to the sensory receptors. However, some complaints, such as taste aversions in patients with cancer, are not related to altered sensory physiology per se but to learned aversions that arise during the noxious effects of radiotherapy and chemotherapy. The paper also reviews a study in which the sensory performance (of all five senses) was compared in three groups of elderly subjects: (1) patients who had undergone coronary artery bypass surgery; (2) patients with cardiovascular conditions but with no history of surgery; (3) healthy non-medicated age-matched controls. Performance of patients who had undergone coronary artery bypass surgery was worse than that for the other two groups, with taste and smell losses greater than for the other senses. The study demonstrates that critical illness (e.g. coronary artery bypass surgery) can exacerbate sensory losses in an older cohort.

Chemosensory changes experienced by patients undergoing cancer chemotherapy: a qualitative interview study

Few studies explore patients' experiences of smell and taste changes during cytotoxic chemotherapy. Issues, such as how such changes impact daily life, their consequences, and how patients respond to chemotherapy-induced chemosensory changes, have not previously been systematically addressed. The aim of this study was to examine these questions by exploring experiences of chemotherapy-induced chemosensory changes. In this qualitative longitudinal study, semistructured interviews were conducted with 14 women and 7 men with a variety of cancer diagnoses, who were known to have smell and taste changes. The participants were chosen for heterogeneity in regard to factors that might impact on experiences of chemotherapy. Participants were followed monthly until chemosensory changes ceased. There was great individual variation in patterns, intensity and impact of smell and/or taste changes, with changes reported to have ceased in all participants within 3.5 months after treatment ended. While not all participants found reported changes "bothersome," those who did reported predominantly emotional and social consequences. Smell and taste changes were said to be influenced by, or to influence, other symptoms, for example, appetite loss, early satiation, nausea, and oral problems. Although participants said they lacked ways to manage chemosensory changes, coping strategies described included frequent oral hygiene, searching for tolerable food, relying on smell and taste memory, and acceptance of changes. Although chemosensory changes resolved in all participants within several months after completed chemotherapy, the reported variation in experiences of taste and smell changes makes these side effects especially challenging to assess and alleviate.

Regenerative capacity of neural precursors in the adult mammalian brain is under the control of p53

The question of whether or not stem cell loss drives aging in the brain has not been fully resolved. Here, we used mice over-expressing the short isoform of p53 (DeltaNp53 or p44) as a model of aging to gain insight into the cellular mechanisms underlying age-related functional deficits in the brain. By BrdU labeling, we observed an accelerated decline in the number of subventricular zone proliferating cells with age in p44Tg mice compared to mice with normal p53 expression. A 2-3-fold reduction in the number of slowly dividing stem cells was evident in the subventricular zone of 9-12-month-old p44Tg mice, but not in younger p44Tg mice or in normal mice. Consequently, the supply of new olfactory bulb neurons was also reduced. The number and size of neurospheres generated from subventricular zone cells from p44Tg mice was significantly reduced, and cells derived from these neurospheres had limited self-renewal and amplification capacities. At the cellular level, p44 lengthened the cell cycle and affected cell cycle reentry properties, evident by an increased proportion of cells in G0. At the functional level, p44 expression resulted in impaired olfactory discrimination in 15-16-month-old mice. This phenotype is driven by constitutive activation of p53 and constitutive expression of p21(Cip1/waf1) in neural stem cells. Our results demonstrate that p53 plays a crucial role in the maintenance of the regenerative capacity of the brain by regulating the proliferation of stem and progenitor cells.