Sensitivity and Specificity of Self-Reported Olfactory Function in a Home-Based Study of Independent-Living, Healthy Older Women

Prevalence and Magnitude of Olfactory Dysfunction in Allergic Rhinitis

BACKGROUND

Although allergic rhinitis (AR) can negatively impact the ability to smell, the degree to which this occurs is not clear and prevalence estimates vary among studies. This study had 4 main objectives: (1) To estimate the prevalence and the degree of olfactory dysfunction in AR patients; (2) To compare olfactory perception between AR patients with different persistence and severity of symptoms and determine if olfactory testing may aid in differentiating among Allergic Rhinitis and its Impact on Asthma (ARIA) groups; (3) To determine whether allergic reactions to different allergens differentially impact olfactory function, and (4) Verify possible changes in the olfactory epithelium (OE) caused by AR.

METHODS

One hundred thirty-three patients with AR and one hundred controls were tested. The main outcome was the score in University of Pennsylvania Smell Identification Test (UPSIT®). The OE was examined using immunofluorescence markers for neuronal activity, apoptosis, oxidative stress, signal transduction, eosinophils, and epithelial thickness.

RESULTS

Prevalence of olfactory dysfunction in the AR patients was higher (AR: 42.9% vs controls: 9%, P < .001). No difference was found either between intermittent and persistent disease cases (P = .58) or between cases with mild and those with moderate/severe symptomatology (P = .33). Lower olfactory capacity was not associated with the reaction to more (P = .48) or diverse types of allergens (Ps > .05). Although not significant, patients with AR had a greater amount of eosinophilia and a lower amount of cAMP (cyclic adenosine monophosphate) in the OE.

CONCLUSION

The study highlights a higher prevalence of olfactory dysfunction in AR patients compared to controls, but olfactory testing may not effectively differentiate AR severity or allergen sensitivities. Although trends suggest potential pathophysiological changes in the OE of AR patients, further research is needed to validate these findings.

The 8-item NHANES pocket smell test®: Normative data

This study provides normative data useful for interpreting scores from the Pocket Smell Test® (PST®), a brief "scratch & sniff" neuropsychological olfactory screening test comprised of 8 items from the 40-item University of Pennsylvania Smell Identification Test (UPSIT®). We combined 3,485 PST® scores from the 2013 to 2014 National Health and Nutrition Survey (NHANES) of persons 40 years of age and older with equivalent PST® items extracted from an UPSIT® database of 3,900 persons ranging in age from 5 to 99 years. Decade-related age- and gender-adjusted percentile normative data were established across the entire age spectrum. Cut-points for defining clinically useful categories of anosmia, probable microsmia, and normosmia were determined using receiver operating characteristic (ROC) curve analyses. An age-related decline in test scores was evident for both sexes after the age of 40 years, with women outperforming men. Based on the ROC analyses, subjects scoring 3 or less (AUC = 0.81) defines anosmia. Regardless of sex, a score of 7 or 8 on the N-PST® signifies normal function (AUC of 0.71). Probable microsmia is classified as scores extending from 3 to 6. These data provide an accurate means for interpreting PST® scores within a number of clinical and applied settings.

Effects of Culinary Spices on Liking and Consumption of Protein Rich Foods in Community-Dwelling Older Adults

Insufficient protein intake is a common challenge among older adults, leading to loss of muscle mass, decreased function and reduced quality of life. A protein intake of 0.4 g/kg body weight/meal is recommended to help prevent muscle loss. The purpose of this study was to assess whether the protein intake of 0.4 g/kg body weight/meal could be achieved with typical foods and whether culinary spices could enhance protein intake. A lunch meal test was conducted in 100 community-dwelling volunteers; 50 were served a meat entrée and 50 were served a vegetarian entrée with or without added culinary spices. Food consumption, liking and perceived flavor intensity were assessed using a randomized, two-period, within subjects crossover design. Within the meat or vegetarian treatments, there were no differences in entrée or meal intakes between spiced and non-spiced meals. Participants fed meat consumed 0.41 g protein/kg body weight/meal, while the vegetarian intake was 0.25 g protein/kg body weight/meal. The addition of spice to the vegetarian entrée significantly increased liking and flavor intensity of both the entrée and the entire meal, while spice addition only increased flavor for the meat offering. Culinary spices may be a useful tool to improve the liking and flavor of high-quality protein sources among older adults, especially when used with plant-based foods, although improving liking and flavor alone are insufficient to increase protein intake.

Self-awareness of olfactory dysfunction in elderly individuals without neurodegenerative diseases

PURPOSE

The decrease in smell in the elderly population is frequent and considered a natural process. However, sometimes it can be associated with the decline of cognitive functions, and it is considered a warning for the early stage of neurodegenerative diseases and social impairment.

OBJECTIVE

To assess the prevalence of olfactory dysfunction in previous healthy elderly that attended a tertiary hospital in Brazil as escorts and the clinical alterations associated in this population.

METHODS

Subjects 60 years or over attending the University Hospital of Campinas were evaluated. Each participant answered a questionnaire, followed by an otorhinolaryngological exam with flexible nasal endoscopy and the Connecticut smell test produced by the Connecticut Chemosensory Clinical Research Center (CCCRC). Elderly people with nasosinusal diseases or with a history of nasal surgery were excluded.

RESULTS

Of the total of 103 participants, 16 (15.5%) reported olfactory complaints and 68 (66%) presented impairment in the olfactory test. It was observed that older individuals showed more changes in olfactory function (p = 0.001). Gender, education, lifestyle, comorbidities, medications in use and exposure to pollutants did not influence the impairment olfactory function of this population.

CONCLUSIONS

There is a significant prevalence of olfactory dysfunction in the elderly population evaluated. Most of these elderlies also present an inability to identify odours, not having awareness of this olfactory impairment.

Olfactory evaluation in hospitalised and self-isolated patients with COVID-19: a single-centre experience on 55 cases

BACKGROUND

Smell loss is a common symptom of COVID-19 infection. Majority of the studies that evaluated olfactory impairment in COVID-19 used questionnaires (subjective smell evaluations) and did not compare the results with objective or semiobjective measures of smell. We performed smell testing in hospitalised and self-isolated patients with COVID-19 and control participants.

METHODS

Fifty-five COVID-19 and 44 control participants underwent smell testing, using Burghart Sniffin' Sticks 'Screening 12 Test'. Participants also rated their smelling capability on the numerical scale. Differences between groups and correlation between smell loss and time from acute onset of symptoms were tested, as well as correlation between results of smell test and subjective assessment of smell.

RESULTS

Hospitalised patients with COVID-19 correctly determined 6.5/12 odorants compared with 10/12 in the self-isolated and 11/12 in the control group (p<0.001). Hyposmia or anosmia were present in 87.5% of hospitalised and 29.0% of self-isolated patients (p<0.001). The correlation between subjective self-assessment and results of smell testing was non-significant in both groups of patients with COVID-19, while there was a moderate positive correlation (p=0.001, Spearman's correlation coefficient=0.499) in control participants.

CONCLUSION

Contrary to some previous reports suggesting that the presence of olfactory loss may predict milder course of disease, our study found that a vast majority of hospitalised patients with COVID-19 had prominent olfactory impairment. The absence of correlation between self-rated and objective smell evaluation in patients with COVID-19 indicates that subjective smell assessment is unreliable.

Chemosensory Dysfunction in Long-Term COVID-19 Assessed by Self-Reported and Direct Psychophysical Methods

Chemosensory dysfunction is a frequent postacute sequela of COVID-19. Depending on the type of test used to measure it (self-report vs. direct test), the degree of chemosensory dysfunction in long-term COVID-19 has been found to be highly variable. In this manuscript, we report the cross-sectional data (first assessment) of a longitudinal study (6-month follow-up) examining smell, taste, and chemesthesis in participants affected by long-term COVID-19 (COVID+) and participants without COVID-19 (COVID−) by means of both self-reported and direct psychophysical methods. In total, 208 Italian participants (COVID+ n = 133; COVID− n = 75) completed the Smell and Taste Check developed by the Global Consortium for Chemosensory Research (GCCR), which includes self-reports on smell, taste, and chemesthetic abilities as well as direct intensity ratings of unstandardized smell, taste, and chemesthetic household items. Furthermore, all participants completed SCENTinel, a validated direct smell test. We found a positive association between the self-reported, unstandardized direct test and the validated direct test for smell, indicating moderate to large agreement across measures. Furthermore, the performance on SCENTinel was significantly associated with self-reported smell loss. A positive association between the self-reports and the intensity of household items was also retrieved for taste and chemesthesis. The time relative to COVID-19 onset (267.3 ± 113.9 days) did not modulate the chemosensory performance of self-reported abilities, intensity ratings, and SCENTinel. All in all, we confirm the impairment of three chemical senses (smell, taste, and chemesthesis) in an independent sample of Italian participants affected by long-term COVID-19 by using and comparing self-reported and direct psychophysical methods. We contribute to the discussion on best practices to monitor chemosensory dysfunction in individuals affected by long-term COVID-19.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Self-Reported Olfactory Dysfunction and Diet Quality: Findings from the 2011-2014 National Health and Nutrition Examination Survey (NHANES)

We identified associations between self-reported olfactory dysfunction (OD) and dietary attributes in participants aged ≥40 years (n = 6,356) from the nationally representative 2011–2014 National Health and Nutrition Examination Survey (NHANES). The chemosensory questionnaire and 24-h dietary recalls were administered by trained interviewers. OD was defined as self-report of either smell problems in the last year, worse smell relative to age 25, or perceiving phantom odors. Dietary outcomes included Healthy Eating Index 2015 score (HEI) with adequacy and moderation components (higher scores indicated higher diet quality), dietary diversity, energy density, and intake of major food groups. Survey-weighted linear regression models estimated OD–diet associations, adjusting for socio-demographic, lifestyle, and clinical factors. Adjusted mean difference (95% CI) between those with versus without OD, showed that adults with OD had significantly lower HEI moderation score (−0.67 (−1.22, −0.11)) and diets higher in energy density (0.06 (0.00, 0.11)), and percent energy from saturated fat (0.47 (0.12, 0.81)), total fat (0.96 (0.22, 1.70)), and added sugar (1.00 (0.33, 1.66)). Age and sex-stratified analyses showed that younger females (40–64 years) primarily accounted for the associations with diet quality and total/saturated fat intake. These findings inform dietary screening and recommendations for adults who report OD, including those experiencing transient or persistent smell loss with COVID-19.

Olfactory dysfunction in aging and neurodegenerative diseases

Alterations in olfactory functions are proposed to be early biomarkers for neurodegeneration. Many neurodegenerative diseases are age-related, including two of the most common, Parkinson's disease (PD) and Alzheimer's disease (AD). The establishment of biomarkers that promote early risk identification is critical for the implementation of early treatment to postpone or avert pathological development. Olfactory dysfunction (OD) is seen in 90% of early-stage PD patients and 85% of patients with early-stage AD, which makes it an attractive biomarker for early diagnosis of these diseases. Here, we systematically review widely applied smelling tests available for humans as well as olfaction assessments performed in some animal models and the relationships between OD and normal aging, PD, AD, and other conditions. The utility of OD as a biomarker for neurodegenerative disease diagnosis and future research directions are also discussed.

Discordance Between Subjective and Objective Measures of Smell and Taste in US Adults

OBJECTIVE

Examine the rates and factors associated with under- and overreporting of subjective changes in smell or taste as compared with objective measures.

STUDY DESIGN

Cross-sectional analysis.

SETTING

National Health and Nutrition Examination Survey (2013-2014).

METHODS

We examined participants ≥40 years old who completed subjective questionnaires (smell, n = 3510; taste, n = 3089), validated objective 8-odor pocket smell tests, and NaCl/quinine taste tests. Over- and underreporting was determined by the difference in subjective and objective results. Univariate and multivariate logistic regression analyses incorporated sampling weights.

RESULTS

A majority of participants correctly classified impairment: smell (73.7%; 95% CI, 71.2%-76.1%) and taste (78.3%; 95% CI, 75.6%-80.7%). Age ≥65 years (odds ratio, 2.23; P = .001) was associated with underreporting impairment, and persistent cold symptoms (odds ratio, 2.15; P = .001) were associated with overreporting smell impairment. Smoke, onion, and natural gas scents were incorrectly identified more frequently by individuals aged ≥65 years after Bonferroni correction. No factors were associated with under- and overreporting taste impairment.

CONCLUSION

Although the concordance rate between subjective and objective assessment of smell and taste impairment remains high, we found that older age was associated with incorrect report of impairment. This suggests that the subjective perception of smell varies across demographical and clinical factors, and it is important to not overlook such factors in clinical practice. Potentially using a simplified odor assessment regularly in the clinical setting may aid in early detection and intervention.

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.

Smell and Taste Impairment in a Nationwide Sample of US Adults With Chronic Rhinosinusitis Symptoms

Objective

To estimate the prevalence of objectively confirmed olfactory and gustatory dysfunction in US adults reporting chronic rhinosinusitis (CRS) symptoms in a nationally representative database.

Study Design

Cross-sectional epidemiologic analysis.

Setting

Data were analyzed from the smell and taste component of the 2013-2014 NHANES data set (National Health and Nutrition Examination Survey).

Methods

Individuals reporting the presence of ≥2 cardinal CRS symptoms (nasal blockage, sinus pain, discolored mucus, and dysosmia) were identified as patients with a potential diagnosis of CRS. Associations were examined between the presence of CRS symptoms and both self-reported and objectively measured smell and taste.

Results

One-third (33%) of adults who have ≥2 CRS symptoms report subjective olfactory impairment, though only 18% of these adults have quantifiable olfactory dysfunction on objective testing. Of these adults, 27% report subjective taste impairment, but just 17% have quantifiable gustatory dysfunction on objective testing. The presence of ≥2 CRS symptoms was not significantly associated with objective olfactory or gustatory dysfunction, although the individual symptoms of subjective dysosmia and discolored mucus were associated with objectively confirmed olfactory dysfunction.

Conclusion

The prevalence of objective olfactory and gustatory dysfunction was higher among adults reporting the presence of ≥2 CRS symptoms, but the differences were not statistically significant. Specific sinonasal symptoms, including discolored mucus and subjective smell dysfunction, were significantly associated with objective smell impairment.

NIH Workshop Report: sensory nutrition and disease

In November 2019, the NIH held the "Sensory Nutrition and Disease" workshop to challenge multidisciplinary researchers working at the interface of sensory science, food science, psychology, neuroscience, nutrition, and health sciences to explore how chemosensation influences dietary choice and health. This report summarizes deliberations of the workshop, as well as follow-up discussion in the wake of the current pandemic. Three topics were addressed: A) the need to optimize human chemosensory testing and assessment, B) the plasticity of chemosensory systems, and C) the interplay of chemosensory signals, cognitive signals, dietary intake, and metabolism. Several ways to advance sensory nutrition research emerged from the workshop: 1) refining methods to measure chemosensation in large cohort studies and validating measures that reflect perception of complex chemosensations relevant to dietary choice; 2) characterizing interindividual differences in chemosensory function and how they affect ingestive behaviors, health, and disease risk; 3) defining circuit-level organization and function that link and interact with gustatory, olfactory, homeostatic, visceral, and cognitive systems; and 4) discovering new ligands for chemosensory receptors (e.g., those produced by the microbiome) and cataloging cell types expressing these receptors. Several of these priorities were made more urgent by the current pandemic because infection with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the ensuing coronavirus disease of 2019 has direct short- and perhaps long-term effects on flavor perception. There is increasing evidence of functional interactions between the chemosensory and nutritional sciences. Better characterization of this interface is expected to yield insights to promote health, mitigate disease risk, and guide nutrition policy.

Olfactory loss and aging: connections with health and well-being

Age-related olfactory dysfunction, or presbyosmia, is a common sensory impairment in aging adults. People in this demographic group with comorbid conditions or exposure to viral, traumatic, or environmental insults remain at the greatest risk for impairment. Several methods for assessing olfaction exist, but they are only available in special settings and require consideration of age, sex, ancestry, and cognition. Perhaps most importantly, olfactory dysfunction has been suggested as an early sign of Alzheimer's and Parkinson's disease and therefore may serve as a tool in the diagnosis and prognosis of these neurodegenerative conditions. Outside of this context, olfactory loss also impacts nutrition, safety, and social relationships, and even predicts mortality itself. This review covers the detection and manifestations of olfactory decline in aging individuals and the myriad ways in which olfactory impairment is connected to their health and well-being.

Identifying Treatments for Taste and Smell Disorders: Gaps and Opportunities

The chemical senses of taste and smell play a vital role in conveying information about ourselves and our environment. Tastes and smells can warn against danger and also contribute to the daily enjoyment of food, friends and family, and our surroundings. Over 12% of the US population is estimated to experience taste and smell (chemosensory) dysfunction. Yet, despite this high prevalence, long-term, effective treatments for these disorders have been largely elusive. Clinical successes in other sensory systems, including hearing and vision, have led to new hope for developments in the treatment of chemosensory disorders. To accelerate cures, we convened the "Identifying Treatments for Taste and Smell Disorders" conference, bringing together basic and translational sensory scientists, health care professionals, and patients to identify gaps in our current understanding of chemosensory dysfunction and next steps in a broad-based research strategy. Their suggestions for high-yield next steps were focused in 3 areas: increasing awareness and research capacity (e.g., patient advocacy), developing and enhancing clinical measures of taste and smell, and supporting new avenues of research into cellular and therapeutic approaches (e.g., developing human chemosensory cell lines, stem cells, and gene therapy approaches). These long-term strategies led to specific suggestions for immediate research priorities that focus on expanding our understanding of specific responses of chemosensory cells and developing valuable assays to identify and document cell development, regeneration, and function. Addressing these high-priority areas should accelerate the development of novel and effective treatments for taste and smell disorders.

Chronic Cigarette Smoking Associates Directly and Indirectly with Self-Reported Olfactory Alterations: Analysis of the 2011-2014 National Health and Nutrition Examination Survey

INTRODUCTION

Population-based studies show inconsistent effects of cigarette smoking on olfactory function. We aimed to identify direct and indirect associations between measures of smoking exposure/nicotine dependence and altered olfaction in a nationally representative sample of adults.

METHODS

NHANES 2011-2014 (n = 7418) participants (mean age = 57.8 ± 12.2 years) self-reported olfaction and related health and demographic risks. Affirmative answers to three questions defined altered olfaction (olfactory problems in the past years; worse ability since age 25; phantom smells). Smoking (never, former, current) was self-reported by chronicity (pack years, PY) and dependency (time to first cigarette upon waking) and verified by serum cotinine. Associations were tested with logistic regression, reporting odds ratios (ORs) and 95% confidence intervals (CIs), and mediation models.

RESULTS

Estimated prevalence of altered olfaction was 22.3%, with age-related increases. Nearly half of the sample were former/current smokers (47.4%). Controlling for olfactory-related risks, ≥10 PY smokers had significantly greater odds of altered olfaction versus never smokers (OR 1.36, CI: 1.06-1.74). The odds of altered olfaction were heightened among current smokers (≥10 PY) who also had high nicotine dependence (smoked ≤30 min of waking) (OR 1.41, CI: 1.01-1.99). Light smokers (≤10 PY smokers) did not show increased odds versus never smokers. Current smokers who also were heavy drinkers (≥4 drinks/day) had the highest odds for altered olfaction (OR 1.96, CI: 1.20-3.19). Olfactory-related pathologies (sinonasal problems, serious head injury, tonsillectomy, xerostomia) partially mediated the association between smoking and altered olfaction.

CONCLUSIONS

Chronic cigarette smoking was associated with increased odds of self-reported olfactory alterations, directly and indirectly via olfactory-related pathologies.

IMPLICATIONS

Analysis of the US nationally representative data revealed significant positive associations between chronic smoking and alterations in the sense of smell. Rates of smell alteration (self-reported problems in the past year, losses with aging, and phantom smells) increased from 23% among adults to 33% for chronic smokers and 38% for chronic smokers who also reported heavy drinking. Chronic smoking showed associations with smell alteration that were direct and indirect through exposure to olfactory-related pathologies (naso-sinus problems, dry mouth, head/facial injury). Smell alteration can impact smokers' quality of life by challenging the ability to sense warning odors, food flavor, and olfactory-stimulated emotions and memories.

Influences of Age, Sex and Smoking Habit on Flavor Recognition in Healthy Population

(1) Background: Flavor is one of the main factors influencing food preferences and dietary choices, and a reduction in flavor recognition has been associated with several diseases. A novel quantitative test to assess flavor has been recently developed and validated. The aim of the present work was to define the standard of flavor recognition in the general healthy population. (2) Methods: Three hundred and forty-eight healthy volunteers (18–80 years) performed the flavor test (FT). The test consisted of the oral administration of aqueous aromatic solutions, identifying 21 different compounds. Flavor score (FS) was calculated as the sum of the properly recognized flavors (range 0–21). (3) Results: Normal ranges for FT were produced. Flavor recognition was found to decrease with age. Females obtained slightly higher scores than males, mostly at older ages. Cigarette smoking seemed not to influence flavor recognition. (4) Conclusion: The normal values found for the flavor test in the healthy population will allow its usage as a diagnostic tool in several diseases.

Associations of olfactory dysfunction with anthropometric and cardiometabolic measures: Findings from the 2013-2014 national health and nutrition examination survey (NHANES)

We examined associations of olfactory dysfunction with anthropometric and cardiometabolic measures in a nationally representative sample of US adults. In the 2013-2014 National Health and Nutrition Examination Survey (NHANES), 3,815 participants, 40 years and older, completed a standardized taste and smell protocol, which consisted of an 8-item odor identification test and a chemosensory questionnaire. Measured dysfunction was incorrect identification of ≥3 of 8 odors; self-reported dysfunction was affirmative response to either a recent smell problem, worse ability since age 25, or phantosmia. Survey-weighted linear regression models tested associations of olfactory dysfunction with body mass index (BMI), waist circumference (WC), blood pressure, serum total cholesterol (TC) with fractions, triglycerides, and glucose levels. Models were adjusted for age, race, education, physical activity, self-reported general health condition, smoking history, and income-to-poverty ratio, stratifying by sex and age group (middle-age 40-64 years; older ≥65 years). Relative to normal, measured olfactory dysfunction was associated with lower BMI [β=-1.6 (95% CI: -3.2, -0.01)] in older men. In middle-age women, dysfunction was associated with higher BMI and WC, whether assessed by examination [β's for BMI=3.1 (0.6, 5.5), WC=5.0 (0.3, 9.8)] or self-report [β's for BMI=2.5 (0.6, 4.3), WC=6.1 (2.2, 9.9)]. Measured dysfunction was associated with significantly higher TC [β=12.8 (7.5, 18.1)] and LDL [β=18.1 (9.1, 27.2)] among older men, but significantly lower TC [β=-15.0 (-25.0, -5.7)] and marginally lower LDL [β=-12.0 (-25.0, 1.2)] among older women. Between measured dysfunction and fasting glucose, the association was inverse [β=-7.9 (-13.0, -2.6)] among middle-age men, but positive [β=15.6 (1.5, 29.7)] among older women. No significant associations were observed with blood pressure levels. In conclusion, among US adults ≥40 years, olfactory dysfunction is associated with anthropometric and glucose and lipid levels, with associations varying by sex and age group.

High Pesticide Exposure Events and Olfactory Impairment among U.S. Farmers

BACKGROUND

Olfactory impairment (OI) is common among older adults and independently predicts all-cause mortality and the risk of several major neurodegenerative diseases. Pesticide exposure may impair olfaction, but empirical evidence is lacking.

OBJECTIVE

We aimed to examine high pesticide exposure events (HPEEs) in relation to self-reported OI in participants in the Agricultural Health Study (AHS).

METHODS

We conducted multivariable logistic regression to examine the associations between HPEEs reported at enrollment (1993–1997) and self-reported OI at the latest AHS follow-up (2013–2015) among 11,232 farmers, using farmers without HPEEs as the reference or unexposed group.

RESULTS

A total of 1,186 (10.6%) farmers reported OI. A history of HPEEs reported at enrollment was associated with a higher likelihood of reporting OI two decades later {odds ratio [Formula: see text] [95% confidence interval (CI): 1.28, 1.73]}. In the analyses on the HPEE involving the highest exposure, the association appears to be stronger when there was a [Formula: see text] delay between HPEE and washing with soap and water [e.g., [Formula: see text] (95% CI: 1.48, 2.89) for 4-6 h vs. [Formula: see text] (95% CI: 1.11, 1.75) for [Formula: see text]]. Further, significant associations were observed both for HPEEs involving the respiratory or digestive tract [[Formula: see text] (95% CI: 1.22, 1.92)] and dermal contact [[Formula: see text] (95% CI: 1.22, 1.78)]. Finally, we found significant associations with several specific pesticides involved in the highest exposed HPEEs, including two organochlorine insecticides (DDT and lindane) and four herbicides (alachlor, metolachlor, 2,4-D, and pendimethalin). HPEEs that occurred after enrollment were also associated with OI development.

CONCLUSIONS

HPEEs may cause long-lasting olfactory deficit. Future studies should confirm these findings with objectively assessed OI and also investigate potential mechanisms. https://doi.org/10.1289/EHP3713.

Heightened olfactory dysfunction and oral irritation among chronic smokers and heightened propylthiouracil (PROP) bitterness among menthol smokers

Chronic cigarette smoking may influence chemosensory function, which in turn, may affect cigarette usage. Because menthol in cigarettes can attenuate nicotine bitterness, choice of menthol/nonmenthol cigarettes may be influenced by ability to perceive bitterness. We examined chemosensory function of chronic smokers, hypothesizing they would show altered function in comparison to non-smokers and by menthol cigarette preference. In laboratory-based measures, chronic smokers (N = 135; 84 menthol smokers) self-reported their chemosensory function and participated in smell (identification task with perceived intensity) and taste (quinine and NaCl intensity on tongue-tip and whole mouth) testing. A taste genetics probe (propylthiouracil (PROP) bitterness) also was assessed. Self-reported and measured chemosensory function were compared with nationally-representative 2013-2014 National Health and Nutrition Examination Survey (NHANES) data generated with similar measures. The taste measures also were compared between smokers and age- and sex-matched non-smokers from a laboratory database. Frequencies of self-reported smell and taste alterations among smokers exceeded NHANES prevalence estimates for non-smokers. The rate of measured smell dysfunction also exceeded NHANES prevalence for hyposmia. Compared to non-smokers, smokers reported elevated tongue-tip and whole mouth intensities from 1 M NaCl, with no significant differences in whole mouth quinine or 0.32 M NaCl. Inconsistent with previous hypotheses, smokers were not more likely to report depressed PROP bitterness than non-smokers. However, as expected, menthol smokers reported greater PROP bitterness than non-menthol smokers. In conclusion, chemosensory alterations were more frequent among chronic smokers, including hyposmia and heightened intensity from NaCl at an oral-irritant concentration. PROP supertasters were most likely to prefer mentholated cigarettes.

Factors Associated with Inaccurate Self-Reporting of Olfactory Dysfunction in Older US Adults

Self-reported olfactory function has poor sensitivity (i.e., people with measured olfactory dysfunction are unlikely to accurately report it). We aimed to identify factors associated with lack of awareness of smell dysfunction. Objective odor identification was evaluated using a validated 5-item test in respondents from the National Social Life, Health, and Aging Project, a representative sample of home-dwelling, US adults ages 57-85 (n = 1468). Self-reported olfaction was assessed with a 5-point Likert scale. Using multivariate logistic regression, we tested factors that might influence inaccuracy of self-reported olfaction, including age, gender, race/ethnicity, education, marital status, cognition, comorbidity, smoking, depression, anxiety, self-rated mental and physical health, and social activity. Among older US adults, 12.4% reported their sense of smell as fair or poor, while 22.0% had objective olfactory dysfunction (≤3 items correct out of 5). Among those with measured olfactory dysfunction, 74.2% did not recognize it; these individuals were more likely to be older, Black, never married, and to have worse cognitive function compared to individuals who recognized their dysfunction (P < 0.05, all). Individuals who lacked awareness of their olfactory dysfunction had the greatest cognitive impairment at 5-year follow-up, followed by individuals aware of their dysfunction and finally normosmics (P < 0.001). Older Americans with measured olfactory dysfunction are unlikely to report it, and those who lack awareness of this dysfunction have distinct demographic, social, and cognitive characteristics. Therefore, clinicians should objectively test patients. Individuals who lack awareness of their olfactory dysfunction have poor cognitive outcomes and should receive additional clinical scrutiny.

Sensory Functioning in Older Adults: Relevance for Food Preference

The world's population is aging and older adults represent the fastest growing segment of the consumer market. Changes in sensory, perceptual and cognitive function in this segment of the population have been described psychophysically, however, more is known about the young-old than the old-old or oldest-old. Only now are we exploring the potential for neuroimaging tools to probe the changes in central nervous system function related to taste and smell that are relevant to sensory perception, reward value, anticipation of and consumption of food stimuli. There is real potential for brain imaging to provide a greater understanding of older adults' consumer behavior.

On the nose: Olfactory disturbances in patients with transient epileptic amnesia

OBJECTIVE

While olfactory hallucinations are relatively rare in epilepsy, a high prevalence (up to 42%) has been reported in one form - Transient Epileptic Amnesia (TEA). TEA is characterized by recurring amnestic seizures and is commonly associated with persistent interictal memory deficits. Despite reports of changes in smell, olfactory ability has not been objectively assessed in this group. The aim of this study was to measure olfactory ability in patients with TEA and explore whether olfactory symptoms relate to other clinical variables.

METHODS

Fifty-five participants with TEA were recruited from The Impairment of Memory in Epilepsy project database. The presence of olfactory symptoms was obtained via case notes and clinical interview. Participants completed questionnaires to evaluate their olfaction and memory function subjectively. Olfactory ability was measured using the University of Pennsylvania Smell Identification Test (UPSIT). TEA participants' performance was compared to 50 matched healthy control participants. A subset of TEA participants (n=26) also completed a battery of memory tests including standard neuropsychological measures, and assessment of accelerated long-term forgetting and autobiographical memory.

RESULTS

Olfactory hallucinations were reported in 55% of patients with TEA. A significant reduction in smell identification (UPSIT) was found between patients with TEA and healthy controls (p<0.001). Epilepsy variables, including history of olfactory hallucinations, were not predictive of olfactory ability. Patients reported ongoing memory difficulties and performed below normative values on objective tests. While no correlation was found between objective measures of memory and olfactory performance, subjective complaints of route finding difficulty was associated with UPSIT score.

CONCLUSIONS

Impairments in odor identification are common in patients with TEA and exceed changes that occur in normal aging. Olfactory hallucinations occurs in approximately half of patients with TEA, but do not always coincide with reduced sense of smell. Olfactory impairment and interictal memory problems both occur frequently in TEA but are not closely associated.

Effects of Ambient Air Pollution Exposure on Olfaction: A Review

BACKGROUND

Olfactory dysfunction affects millions of people worldwide. This sensory impairment is associated with neurodegenerative disease and significantly decreased quality of life. Exposure to airborne pollutants has been implicated in olfactory decline, likely due to the anatomic susceptibility of the olfactory nerve to the environment. Historically, studies have focused on occupational exposures, but more recent studies have considered effects from exposure to ambient air pollutants.

OBJECTIVES

To examine all relevant human data evaluating a link between ambient pollution exposure and olfaction and to review supporting animal data in order to examine potential mechanisms for pollution-associated olfactory loss.

METHODS

We identified and reviewed relevant articles from 1950 to 2015 using PubMed and Web of Science and focusing on human epidemiologic and pathophysiologic studies. Animal studies were included only to support pertinent data on humans. We reviewed findings from these studies evaluating a relationship between environmental pollutant exposure and olfactory function.

RESULTS

We identified and reviewed 17 articles, with 1 additional article added from a bibliography search, for a total of 18 human studies. There is evidence in human epidemiologic and pathologic studies that increased exposure to ambient air pollutants is associated with olfactory dysfunction. However, most studies have used proxies for pollution exposure in small samples of convenience. Human pathologic studies, with supporting animal work, have also shown that air pollution can contact the olfactory epithelium, translocate to the olfactory bulb, and migrate to the olfactory cortex. Pollutants can deposit at each location, causing direct damage and disruption of tissue morphology or inducing local inflammation and cellular stress responses.

CONCLUSIONS

Ambient air pollution may impact human olfactory function. Additional studies are needed to examine air pollution-related olfactory impacts on the general population using measured pollution exposures and to link pollution exposure with olfactory dysfunction and related pathology. Citation: Ajmani GS, Suh HH, Pinto JM. 2016. Effects of ambient air pollution exposure on olfaction: a review. Environ Health Perspect 124:1683-1693; http://dx.doi.org/10.1289/EHP136.

Health-Related Quality of Life in Patients with Subjective Cognitive Decline and Mild Cognitive Impairment and its Relation to Activities of Daily Living

BACKGROUND

Health related quality of life (HRQOL) is an important issue in the context of dementia care.

OBJECTIVES

The purpose of this study was to investigate HRQOL in patients with subjective cognitive decline (SCD) and mild cognitive impairment (MCI) and its relation to Activity of Daily Living (ADL).

METHODS

In this cross sectional study, four experimental groups (each n = 98), controls, SCD, naMCI and aMCI, were compared. For data collection, neuropsychological methods (NTBV) and psychological questionnaires (SF-36 and B-ADL) were used. Multivariate analysis of variance was calculated to detect differences in HRQOL between groups. Correlations between HRQOL and ADL were explored.

RESULTS

The dimensions of HRQOL showed mainly consistent differences between the control and the SCD group and MCI subgroups. In almost every dimension of HRQOL, the control group scored higher than subjects with SCD, naMCI, or aMCI. The controls showed low to moderate negative correlations between HQROL and B-ADL in some dimensions of the HRQOL. In the SCD group, low negative correlations with ADL were observed in some HRQOL scales. Low to moderate correlations were found between each scale of the SF-36 and the B-ADL in both MCI subtypes. We found gender differences in HRQOL.

CONCLUSION

In conclusion, we could demonstrate that patients with SCD report reduced quality of life. This knowledge is important to get a better understanding of the individuals with SCD and may pave the way for the development of early intervention.

New chemosensory component in the U.S. National Health and Nutrition Examination Survey (NHANES): first-year results for measured olfactory dysfunction

The U.S. NHANES included chemosensory assessments in the 2011-2014 protocol. We provide an overview of this protocol and 2012 olfactory exam findings. Of the 1818 NHANES participants aged ≥40 years, 1281 (70.5 %) completed the exam; non-participation mostly was due to time constraints. Health technicians administered an 8-item, forced-choice, odor identification task scored as normosmic (6-8 odors identified correctly) versus olfactory dysfunction, including hyposmic (4-5 correct) and anosmic/severe hyposmic (0-3 correct). Interviewers recorded self-reported smell alterations (during past year, since age 25, phantosmia), histories of sinonasal problems, xerostomia, dental extractions, head or facial trauma, and chemosensory-related treatment and changes in quality of life. Olfactory dysfunction was found in 12.4 % (13.3 million adults; 55 % males/45 % females) including 3.2 % anosmic/severe hyposmic (3.4 million; 74 % males/26 % females). Selected age-specific prevalences were 4.2 % (40-49 years), 12.7 % (60-69 years), and 39.4 % (80+ years). Among adults ≥70 years, misidentification rates for warning odors were 20.3 % for smoke and 31.3 % for natural gas. The highest sensitivity (correctly identifying dysfunction) and specificity (correctly identifying normosmia) of self-reported olfactory alteration was among anosmics/severe hyposmics (54.4 % and 78.1 %, respectively). In age- and sex-adjusted logistic regression analysis, risk factors of olfactory dysfunction were racial/ethnic minority, income-to-poverty ratio ≤ 1.1, education <high school, and heavy drinking. Moderate-to-vigorous physical activity reduced risk of impairment. Olfactory dysfunction is prevalent, particularly among older adults. Inexpensive, brief odor identification tests coupled with questions (smell problems past year, since age 25, phantosmia) could screen for marked dysfunction. Healthcare providers should be prepared to offer education on non-olfactory avoidance of hazardous events.

The Epidemiology of Olfactory Disorders

Insights into risk factors for olfactory decline are needed, because knowledge about its origin is limited. This impairment has important implications for human health. Several epidemiologic studies of olfaction provide insight into the prevalence of olfactory disorders. Here, we review the major population studies carried out on this topic to date. Our purpose is to characterize knowledge about olfactory disorders from human studies. We also describe the existing methods for measuring the sense of smell in population studies, present recent insights into the epidemiology of smell disorders, and discuss the risk factors identified to date. Synthesis of these data shows that olfactory dysfunction increases as people age and is worse in men. Further study of olfaction is warranted for gaining better information on the etiologies affecting its impairment, research that will have a large public health impact.

Prevalence and Risk Factors of Self-Reported Smell and Taste Alterations: Results from the 2011-2012 US National Health and Nutrition Examination Survey (NHANES)

Chemosensory problems challenge health through diminished ability to detect warning odors, consume a healthy diet, and maintain quality of life. We examined the prevalence and associated risk factors of self-reported chemosensory alterations in 3603 community-dwelling adults (aged 40+ years), from the nationally representative, US National Health and Nutrition Examination Survey (NHANES) 2011-2012. In this new NHANES component, technicians surveyed adults in the home about perceived smell and taste problems, distortions, and diminished abilities since age 25 (termed "alterations"), and chemosensory-related health risks and behaviors. The prevalence of self-reported smell alteration was 23%, including phantosmia at 6%; taste was 19%, including dysgeusia at 5%. Prevalence rates increased progressively with age, highest in those aged 80+ years (smell, 32%; taste, 27%). In multivariable logistic regression, controlling for sociodemographics, health behaviors, and chemosensory-related conditions, the strongest independent risk factor for smell alteration was sinonasal symptoms (odds ratio [OR] = 2.06; 95% confidence interval [CI]: 1.63-2.61), followed by heavy drinking, loss of consciousness from head injury, family income ≤110% poverty threshold, and xerostomia. For taste, the strongest risk factor was xerostomia (OR = 2.65; 95% CI: 1.97-3.56), followed by nose/facial injury, lower educational attainment, and fair/poor health. Self-reported chemosensory alterations are prevalent in US adults, supporting increased attention to decreasing their modifiable risks, managing safety/health consequences, and expanding chemosensory screening/testing and treatments.

The Taste and Smell Protocol in the 2011-2014 US National Health and Nutrition Examination Survey (NHANES): Test-Retest Reliability and Validity Testing

INTRODUCTION

The US NHANES 2011-2014 protocol includes a taste and smell questionnaire (CSQ) in home-based interviews and brief assessments in mobile exam centers. We report the short- and longer-term test-retest reliability and validity of this protocol against broader chemosensory measures.

METHODS

A convenience sample of 73 adults (age=39.5±20.8 years) underwent the NHANES protocol at baseline, 2 weeks and 6 months. For taste, participants rated intensities of two tastants (1 M NaCl, 1 mM quinine) applied to the tongue tip and three tastants (1 M NaCl, 1 mM quinine, 0.32 M NaCl) sampled with the whole mouth. Smell function was assessed with a Pocket Smell Test™ (PST; eight-item odor identification test). The CSQ asked about chemosensory problems, distortions, and age-related changes. Broader baseline measurements were a 40-item olfactometer-generated identification task and additional whole-mouth taste intensities (1 M sucrose, 32 mM citric acid, 3.2 mM propylthiouracil).

RESULTS

Intraclass correlations (ICCs) for NHANES taste measures showed moderate-to-good agreement after 2 weeks and 6 months (ICCs 0.42-0.71). Whole-mouth quinine intensity was significantly correlated with other taste intensities, supporting its utility as a marker for overall taste functioning. Olfactory classification from PSTs agreed for 98.5 % of participants across 2 weeks (κ=0.85; 95 % CI 0.71-0.99) and had good correspondence with the olfactometer task. CSQ items showed good-to-excellent agreement over 6 months (ICCs 0.66-0.90).

CONCLUSIONS

These findings further support that the NHANES chemosensory protocol has moderate-to-good test-retest reliability when administered to healthy, educated adults. Despite being a brief procedure with limited measures, the NHANES taste and smell assessments provided good information when compared to broader measures of taste and smell function.