Smoking and olfactory dysfunction: A systematic literature review and meta-analysis

Association of nasal surgery with olfactory function among older adults

BACKGROUND/PURPOSE

Olfactory Dysfunction (OD) is a prevalent condition that commonly presents in the older adult population. Various factors have been shown to contribute to OD, such as neurodegenerative disease, older age, and smoking status; however, the influence of nasal surgery on olfactory function is not well delineated. This study seeks to explore the potential effect of nose surgery on olfactory function.

METHODS

This cross-sectional study was conducted on data for 2285 adults from Round 1 of the National Social Life, Health, and Aging Project (NSHAP), a nationally representative sample of US older adults. The 5-item Sniffin' Sticks test was used to define olfactory function: correctly identifying ≥4 odors indicated normal olfactory function, while correctly identifying 0-3 odors was considered OD Associations between prior nasal surgery and OD were assessed using multivariable logistic regression, and adjusted odds ratios (OR) were calculated. Analyses were weighted using NSHAP-provided person-level weights to account for sampling design.

RESULTS

OD was present in 18.4 % of adults. The weighted average age was 67.1 ± 7.2 years among those with normal olfaction and 70.9 ± 7.9 years for those with OD. Of adults with OD, 9.8 % had a prior nasal surgery as compared to 8.1 % of those with normal olfaction, although the difference was not statistically significant. After adjusting for age, gender, race, education, prior stroke, dementia, and self-reported mental health, prior nasal surgery was not significantly associated with OD (OR: 1.14; 95 % CI: 0.77-1.70).

CONCLUSION

Prior nasal surgery was not associated with OD after controlling for covariates. While this study does provide unique insight into the relationship between nasal surgery and OD in nationally representative cohort of older adults, it was limited since the dataset utilized did not contain information on the specific surgery that participants underwent. Therefore, further research with more detailed information on the types of nasal surgeries and sinonasal conditions prior to surgery would further help elucidate the relationship between and nasal surgery and OD.

Role and Mechanism of Olfactory Stem Cells in the Treatment of Olfactory Disorders

Olfactory dysfunction is one of the most prevalent diseases in otorhinolaryngology, particularly since the coronavirus 2019 (COVID-19) pandemic, with a potential impact on daily life. Several etiological factors can contribute to olfactory dysfunction owing to the complexity and specificity of the olfactory transmission pathway. However, current treatments for olfactory dysfunction are limited and their efficacy is unsatisfactory. Olfactory stem cells are multifunctional stem cells in the olfactory mucosa that comprise both horizontal and global basal stem cells (HBCs and GBCs, respectively). These cells can differentiate into various cell types in response to different stimuli with distinct characteristics. The aim of the study was to discuss the mechanisms and functions of stem cells and their application in the treatment of olfactory dysfunction.

Chronic Sinusitis With Nasal Polyps and Olfactory Dysfunction: Comparing Olfactory Training and Glucocorticoid Treatment

OBJECTIVE

Few studies have compared the effectiveness of olfactory training (OT) and glucocorticoids (GC) in the phenotype of chronic sinusitis with nasal polyps (CRSwNP) with olfactory dysfunction (OD). To evaluate the effects of GC and OT on OD in patients with eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) and non-eosinophilic chronic rhinosinusitis with nasal polyps (NonECRSwNP).

METHODS

After 2 weeks of endoscopic sinus surgery, patients with a composite threshold discrimination identification score (TDIS) of less than 30.5 were randomly assigned to receive GC (n = 38), OT (n = 36), or both (n = 34). Retrospective phenotypic stratification of CRSwNP patients was performed based on whether eosinophils in the tissue exceeded 10% (ECRSwNP and NonECRSwNP). Follow-up assessments were conducted at 1, 3, and 6 months postintervention. Evaluations included TDIS, the 22-item Sino-Nasal outcome test (SNOT-22), Lund-Kennedy endoscopic scores (LKES), and the frequency of olfactory fluctuations (OF).

RESULTS

SNOT-22 and LKES improved significantly over time. At 1 month, TDIS change was higher in the GCwOT group than in the GC or OT groups. By 6 months, GCwOT remained superior to GC but not to OT. Follow-up showed no difference between GC and OT. In ECRSwNP patients, GCwOT showed greater TDIS changes at 3 and 6 months versus GC, with lower OF incidence (p < 0.0125). In NonECRSwNP, GCwOT outperformed OT only at 1 month.

CONCLUSION

GC combined with OT can reduce OF in patients with ECRSwNP and consistently enhance olfactory function.

LEVEL OF EVIDENCE: 2

TRIAL REGISTRATION

ChiCTR2100049551.

Cerebrovascular burden and neurodegeneration linked to 15-year odor identification decline in older adults

Background

The mechanisms underlying olfactory decline in aging need further investigation. Noticeably, the longitudinal relationship of biological markers with olfaction remains underexplored. We investigated whether baseline levels and progression of microvascular lesions and brain atrophy are associated with odor identification (OID) decline.

Methods

The association between structural MRI markers and OID decline was examined in participants from the SNAC-K MRI study who were free from dementia at baseline (n = 401, mean age = 70.2 years, 60% females). OID was repeatedly assessed over 15 years. Presence of lacunes, white matter hyperintensities (WMH), perivascular spaces (PVS), and lateral ventricular, hippocampal, amygdalar, and total gray matter (GM) volumes were assessed up to 6 years, concurrent with the first 6 years of olfactory assessments.

Results

Higher PVS count and lower hippocampal and GM volumes at baseline were associated with accelerated OID decline (pFWE  < 0.05). Longitudinally (n = 225), presence of lacunes at follow-up, faster WMH volume and PVS count increases, faster lateral ventricular enlargement, and faster hippocampal, amygdalar, and GM atrophy were associated with accelerated OID decline (p FWE < 0.05).

Conclusion

Olfactory decline is related to both increased cerebrovascular burden and accelerated brain atrophy over time.

Brain-wide pleiotropy investigation of alcohol drinking and tobacco smoking behaviors

To investigate the pleiotropic mechanisms linking brain structure and function to alcohol drinking and tobacco smoking, we integrated genome-wide data generated by the GWAS and Sequencing Consortium of Alcohol and Nicotine use (GSCAN; up to 805,431 participants) with information related to 3935 brain imaging-derived phenotypes (IDPs) available from UK Biobank (N = 33,224). We observed global genetic correlation of smoking behaviors with white matter hyperintensities, the morphology of the superior longitudinal fasciculus, and the mean thickness of pole-occipital. With respect to the latter brain IDP, we identified a local genetic correlation with age at which the individual began smoking regularly (hg38 chr2:35,895,678-36,640,246: rho = 1, p = 1.01 × 10-5). This region has been previously associated with smoking initiation, educational attainment, chronotype, and cortical thickness. Our genetically informed causal inference analysis using both latent causal variable approach and Mendelian randomization linked the activity of prefrontal and premotor cortex and that of superior and inferior precentral sulci, and cingulate sulci to the number of alcoholic drinks per week (genetic causality proportion, gcp = 0.38, p = 8.9 × 10-4, rho = -0.18 ± 0.07; inverse variance weighting, IVW beta = -0.04, 95%CI = -0.07--0.01). This relationship could be related to the role of these brain regions in the modulation of reward-seeking motivation and the processing of social cues. Overall, our brain-wide investigation highlighted that different pleiotropic mechanisms likely contribute to the relationship of brain structure and function with alcohol drinking and tobacco smoking, suggesting decision-making activities and chemosensory processing as modulators of propensity towards alcohol and tobacco consumption.

User perception of fluoride mouthwashes for daily use: A randomized clinical trial

AIM

To assess user perceptions of different commercially available fluoride mouthwashes (FL-MWs).

METHODS

A single-blind, randomized clinical trial was conducted. Participants were randomly assigned to a sequence of six different FL-MWs, one of which contained alcohol. For each visit, participants rinsed with one specific mouthwash (15 mL) for 30 s. After rinsing, participants completed a questionnaire with a visual analogue scale. Questions focused on overall taste, mild/pungent feeling, taste duration, foaming effect, burning sensation, sensitivity, numbness, dryness, rinsing time, smell, and colour of the mouthwashes. Descriptive analyses and statistical tests regarding differences among and between the mouthwashes were performed.

RESULTS

Overall, 53 participants completed the study protocol, including nine who did, however, not rinse with the alcohol-containing mouthwash due to religious reasons. Among the mouthwashes, significant differences were found for foaming effect, sensitivity, rinsing time, smell, and colour (p < 0.05). Pairwise comparison for smell did not reveal a difference, and foaming was within the acceptance range (low to medium foaming). Coloured mouthwashes were more appreciated than transparent solutions (p = 0.00). The mouthwash containing essential oils and alcohol produced significantly more sensitivity (p = 0.00) and, in general, participants experienced the rinsing time significantly longer (p < 0.05) compared to the non-alcohol-containing mouthwashes.

CONCLUSION

There is heterogeneity in user perceptions and preferences for FL-MWs, with a significant difference in foaming effect, sensitivity, rinsing time, smell, and colour. Coloured mouthwashes are preferred. The mouthwash containing essential oils and alcohol was less acceptable in relation to sensitivity and rinsing time.

Pharmacovigilance imbalance analysis of VEGFR-TKI-related taste and smell disorders

Taste and smell disorders (TSDs) can induce diminished interest in food, inadequate nutrient intake, and emotional irregularities, particularly among cancer patients. Previous research found that the main culprits of TSD development in cancer patients are cytotoxic drugs such as taxol, fluorouracil, cyclophosphamide, and anthracycline-based drugs. The advent of targeted drugs such as vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) has significantly extended the survival time of cancer patients, and thus widely used in clinical practice. However, the association between the use of VEGFR-TKIs and the development of TSDs havs not been studied.The adverse event(AE) reports related to VEGFR-TKIs were downloaded from the FDA Adverse Event Reporting System (FAERS) database. Disproportionality analysis was conducted to assess the correlation between VEGFR-TKIs and TSDs. The Standardized Medical Dictionary for Regulatory Activities (MedDRA) Queries (SMQs) were used to analyze the AEs of TSDs. The study found a statistically significant correlation between the occurrence of TSDs and the use of VEGF-TKIs (cabozantinib, axitinib, pazopanib, sunitinib, nintedanib, and lenvatinib).However, the instructions for Nintedanib, Sorafenib and Lenvatinib were not mentioned. Capbottinib demonstrated the highest number of reports(1790 cases), also with the strongest association (ROR 95%CI-low = 16.51; PRR = 16.18; IC025 = 3.96) when analyzing the narrow SMQ of TSDs. Dysgeusia, taste disorder, and ageusia were the most commonly reported preferred terms (PTs) in VEGFR-TKI-related TSDs, accounting for more than 90% of the reported cases. Cabozantinib showed the highest number of reports and strongest correlation with ageusia, taste disorder, parosmia, and anosmia. The study found significant association between the reports of TSDs and the use of VEGFR-TKIs, indicating the monitoring of TSD development and appropriate management in clinical is necessary.

The Association of Odor Identification With Nutritional Status and Systemic Inflammation in Patients With Advanced Chronic Kidney Disease

OBJECTIVES

Anorexia is common in patients with chronic kidney disease (CKD) and could lead to protein-energy wasting (PEW). An altered sense of smell, a reflection of olfactory dysfunction, is a potential mechanism that exacerbates the impact of anorexia on PEW. In this study, we examined the extent of the altered sense of smell and its association with PEW in patients with moderate-to-advanced CKD.

METHODS

We studied 139 individuals (34 healthy subjects- controls, 50 patients with stage 3-4 CKD, and 55 patients on maintenance hemodialysis (MHD)) using the odor identification test (Sniffin' Sticks odor screening test containing 12 different smells). The odor identification test was scored as either correct or incorrect, and each participant's total odor score was calculated. Malnutrition inflammation score (MIS) was used to assess PEW.

RESULTS

Patients with CKD had higher C-reactive protein and lower serum albumin concentrations compared to healthy individuals. Total odor scores were different between groups, with controls having the highest scores and MHD patients having the lowest scores. A similar difference was observed in MIS, and MHD patients displayed the worst nutritional score (P ≤ .001). The number of participants with severe olfactory dysfunction (≤6 correct answers) was significantly higher in the CKD and MHD groups compared to the controls (P ≤ .01). There was an inverse trend between the total odor score and the MIS score for the study population. However, this relationship was not statistically significant (r = -0.124, P = .21).

CONCLUSION

This cross-sectional study suggests that olfactory dysfunction, as assessed by the odor identification test, is altered in patients with advanced CKD, most notably in ones on MHD. Although the diminished sense of smell was observed alongside development of PEW, we explicitly noted that there is no statistically significant correlation.

Olfactory neurofeedback: current state and possibilities for further development

This perspective considers the novel concept of olfactory neurofeedback (O-NFB) within the framework of brain-computer interfaces (BCIs), where olfactory stimuli are integrated in various BCI control loops. In particular, electroencephalography (EEG)-based O-NFB systems are capable of incorporating different components of complex olfactory processing - from simple discrimination tasks to using olfactory stimuli for rehabilitation of neurological disorders. In our own work, EEG theta and alpha rhythms were probed as control variables for O-NFB. Additionaly, we developed an olfactory-based instructed-delay task. We suggest that the unique functions of olfaction offer numerous medical and consumer applications where O-NFB is combined with sensory inputs of other modalities within a BCI framework to engage brain plasticity. We discuss the ways O-NFB could be implemented, including the integration of different types of olfactory displays in the experiment set-up and EEG features to be utilized. We emphasize the importance of synchronizing O-NFB with respiratory rhythms, which are known to influence EEG patterns and cognitive processing. Overall, we expect that O-NFB systems will contribute to both practical applications in the clinical world and the basic neuroscience of olfaction.

Inflammation and olfactory loss are associated with at least 139 medical conditions

Olfactory loss accompanies at least 139 neurological, somatic, and congenital/hereditary conditions. This observation leads to the question of whether these associations are correlations or whether they are ever causal. Temporal precedence and prospective predictive power suggest that olfactory loss is causally implicated in many medical conditions. The causal relationship between olfaction with memory dysfunction deserves particular attention because this sensory system has the only direct projection to memory centers. Mechanisms that may underlie the connections between medical conditions and olfactory loss include inflammation as well as neuroanatomical and environmental factors, and all 139 of the medical conditions listed here are also associated with inflammation. Olfactory enrichment shows efficacy for both prevention and treatment, potentially mediated by decreasing inflammation.

Diabetic Neuropathy Is Related to Rhinencephalon Degeneration in Adults With Type 1 Diabetes

Aims: We aimed to assess neurodegenerative changes in the rhinencephalon via magnetic resonance imaging (MRI) and relate it to olfactory function and diabetic peripheral neuropathy (DPN) in adults with type 1 diabetes (T1D). Materials and Methods: Individuals aged 18-65 with T1D duration over 10 years and control healthy subjects underwent olfactory assessment using Sniffin'Sticks and brain MRI to assess volumetric measurements of the olfactory bulbs and piriform cortex thickness. Results: 32 T1D (24 males) aged 43.5 years (IQR: 37.0-48), diabetes duration 24.5 years (IQR: 20.5-27.0), and A1C 7.95% (IQR: 7.4-8.4) were assessed. The control group consisted of 6 healthy adults (4 males) aged 41.0 years (IQR: 36.0-48.0). Significantly lower olfactory test results in TDI (threshold-differentiation-identification) (31.5 (IQR: 28.7-33.6) vs. 34.1 (IQR: 33.2-37.2), p = 0.02) were obtained in the T1D as compared to the controls. Summarized olfactory bulb (OB) volumes and thickness of the left pyriform cortex were significantly smaller in T1D than in controls (65.8 mm3 (IQR: 57.9-71.7) vs. 75.8 mm3 (IQR: 74.8-76.7); p = 0.0005 and 3.1 mm (IQR: 2.7-3.4) vs. 3.6 mm (IQR: 3.5-4.1); p =0.02). Patients with DPN had significantly smaller OB volumes than patients without DPN (58.1 mm3 (IQR: 54.0-70.9) vs. 69.8 mm3 (IQR: 65.0-72.2); p = 0.02). Tobacco smoking (β: -7.89; p = 0.013) and DPN (β:-7.02; p = 0.015) proved to be independent predictors of OB volume. Conclusions: In adults with a long history of T1D, olfactory function and structures are impaired. The presence of diabetic neuropathy and ongoing smoking addiction might be considered predictors of the degradation of rhinencephalon structures in people with T1D.

The association between olfactory subdomains and frailty: A prospective case‒control study investigation

BACKGROUND

Amidst the rise of frailty among a globally aging population, olfactory decline has emerged as a harbinger of frailty and mortality in population-level studies. However, the relationships between frailty and the olfactory subdomains of identification (OI), discrimination (OD), and threshold (OT) remain unexplored. This study prospectively examined the association between olfactory subdomains and the physical frailty phenotype (PFP) to investigate olfactory evaluation as a means of frailty screening.

METHODS

A case‒control study of 45 frail and 45 non-frail individuals matched by age and sex. OT, OD, OI (range 0‒16), and composite sum (threshold, discrimination, and identification scores [TDI], range 0‒48) were measured with Sniffin' Sticks. PFP was defined by presence of three or more criteria: physical inactivity, self-reported exhaustion, muscle weakness, slow gait, and unintentional weight loss. Conditional logistic regression evaluated associations between olfactory subdomains and frailty.

RESULTS

Ninety individuals with mean age of 83.1 ± 4.9 years, 60% female (n = 54), and 87.8% white (n = 79) were included. Olfactory scores were significantly lower in the frail group for OI (9.2 vs. 12.1, p < 0.001), OD (8.1 vs. 11.6, p < 0.001), OT (4.4 vs. 8.5, p < 0.001), and TDI (21.7 vs. 32.2, p < 0.001) than in the non-frail group. A single-point decrease in olfactory score was associated with increased odds of frailty in OT (odds ratio [OR]: 2.21, 95% confidence interval: [1.22, 3.98]), OD (OR: 2.19, 95% CI: [1.32, 3.65]), OI (OR: 2.29, 95% CI: [1.19, 4.39]), and TDI (OR: 1.54, 95% CI: [1.14, 2.08]).

CONCLUSION

The robust association between olfactory subdomain scores and frailty suggests that olfaction may be an accessible signifier of frailty. Future studies should investigate this relationship longitudinally to assess predictive relationships.

Comparison of smoking conventional cigarettes and using heated tobacco products on the olfactory and gustatory function in healthy young adults: A cross-sectional study

INTRODUCTION

Smoking has a negative impact on the chemosensory function. The aim of the study was to evaluate the effects of smoking experience and type of tobacco products on gustatory and olfactory function.

METHODS

This study included 30 conventional cigarette smokers, 30 heated tobacco products (HTPs) users, and 30 non-smokers. Olfactory function was assessed with a 'Sniffin' Sticks Screening 12 Test' while the taste function was assessed with 'taste strips' for the basic tastes of sweet, sour, salty, and bitter. The lifetime exposure to smoking was calculated using the Brinkman index (BI).

RESULTS

Conventional cigarette smokers demonstrated decreased olfactory function in comparison to non-smokers (median: 10 vs 11; p=0.001) but HTPs users did not differ between those two groups. Overall gustatory function was lower in conventional cigarette smokers (median: 9.5) and HTPs users (median: 10) than in non-smokers (median: 14; p<0.001). A difference was detected in the sour, salty and bitter taste but without significant difference between HTPs users and conventional cigarette smokers. Negative linear correlations were found between the BI and olfactory function, overall gustatory function, sour, salty, and bitter taste (r= -0.317 - -0.585; p≤0.002). In multiple linear regression, BI was the only predictor of olfactory dysfunction when controlling for the effect of tobacco products, age, and gender accounting for 11% of variance (p=0.024, R2=0.123). For gustatory dysfunction, BI was the strongest predictor followed by gender and tobacco products accounting for 11%, 5%, and 4% (p<0.001, R2=0.259).

CONCLUSIONS

Olfactory and gustatory function are adversely associated with smoking, more depending on BI than tobacco product.

The Impact of Nicotine Patches on Gingival and Oral Health: A Narrative Review

Smoking significantly impacts oral health, causing periodontal disease, oral cancer, tooth discoloration, halitosis, and impaired wound healing. Nicotine replacement therapy (NRT), particularly nicotine patches, is widely used for smoking cessation. This review evaluates the literature regarding nicotine patches and their implications for oral and gum health. Nicotine patches deliver controlled nicotine doses transdermally, alleviating cravings and withdrawal symptoms. While nicotine can negatively affect oral health through vasoconstriction and reduced salivary flow, the overall impact of patches is generally positive compared to continued smoking. The primary benefit is the elimination of exposure to harmful chemicals and heat from cigarette smoke, significantly decreasing oral cancer risk and periodontal disease progression. Nicotine patches are associated with improved periodontal treatment outcomes, better wound healing, and potential anti-inflammatory effects. They may also promote improved oral hygiene practices. However, limitations include uncertain long-term effects and potential side effects like xerostomia. In conclusion, while nicotine patches may have some oral health effects, their use generally leads to significant improvements compared to continued smoking, making them valuable for promoting better oral health in individuals quitting smoking.

Long-COVID impacts taste and olfactory in individuals with substance use disorder: A retrospective cohort study from the TriNetX US Collaborative Networks

Substance use disorder (SUD) exacerbates the impact of Long-COVID, particularly increasing the risk of taste and olfactory disorders. Analyzing retrospective cohort data from TriNetX and over 33 million records (Jan 2020-Dec 2022), this study focused on 1,512,358 participants, revealing that SUD significantly heightens the likelihood of experiencing taste disturbances and anosmia in Long-COVID sufferers. Results indicated that individuals with SUD face a higher incidence of sensory impairments compared to controls, with older adults and women being particularly vulnerable. Smokers with SUD were found to have an increased risk of olfactory and taste dysfunctions. The findings underscore the importance of early screening, diagnosis, and interventions for Long-COVID patients with a history of SUD, suggesting a need for clinicians to monitor for depression and anxiety linked to sensory dysfunction for comprehensive care.

Relationship between olfactory and gustatory functions: The Iwaki health promotion project 2019

OBJECTIVE

Olfactory and gustatory functions are important sensory aspects in humans. Although they are believed to influence each other, their interrelationship is not well understood. In this study, we aimed to investigate the relationship between the olfactory and gustatory functions based on the results of a large-scale epidemiological study (Iwaki Health Promotion Project) of the general local population.

METHODS

We analyzed 565 participants who underwent taste and olfactory tests in the 2019 Iwaki Project. Gustatory function was tested for four taste qualities (sweet, sour, salty, and bitter) using whole-mouth taste tests. Olfactory function was tested using the University of Pennsylvania Smell Identification Test modified for Japanese (UPSIT-J). We evaluated sex-related differences between olfactory and gustatory functions and the effects of various factors on olfactory identification using multivariate analysis. Furthermore, we compared the percentage of accurate UPSIT-J responses between the normal and hypogeusia groups. We also analyzed the effects of taste and olfactory functions on eating.

RESULTS

Olfactory and gustatory functions were lower in men than in women. Among the four taste qualities, salty taste was the most closely associated with olfactory identification ability, with lower olfactory scores of salty taste in the hypogeusia group than in the normal group. Moreover, the hyposmia group had higher daily salt intake than the normal olfaction group in women.

CONCLUSION

These results suggest that olfactory identification tests may be useful in predicting elevated salt cognitive thresholds, leading to a reduction in salt intake, which may contribute to hypertension prevention.

Brain-wide pleiotropy investigation of alcohol drinking and tobacco smoking behaviors

To investigate the pleiotropic mechanisms linking brain structure and function to alcohol drinking and tobacco smoking, we integrated genome-wide data generated by the GWAS and Sequencing Consortium of Alcohol and Nicotine use (GSCAN; up to 805,431 participants) with information related to 3,935 brain imaging-derived phenotypes (IDPs) available from UK Biobank (N=33,224). We observed global genetic correlation of smoking behaviors with white matter hyperintensities, the morphology of the superior longitudinal fasciculus, and the mean thickness of pole-occipital. With respect to the latter brain IDP, we identified a local genetic correlation with age at which the individual began smoking regularly (hg38 chr2:35,895,678-36,640,246: rho=1, p=1.01×10 -5 ). This region has been previously associated with smoking initiation, educational attainment, chronotype, and cortical thickness. Our genetically informed causal inference analysis using both latent causal variable approach and Mendelian randomization linked the activity of prefrontal and premotor cortex and that of superior and inferior precentral sulci, and cingulate sulci to the number of alcoholic drinks per week (genetic causality proportion, gcp=0.38, p=8.9×10 -4 , rho=-0.18±0.07; inverse variance weighting, IVW beta=-0.04, 95%CI=-0.07 - -0.01). This relationship could be related to the role of these brain regions in the modulation of reward-seeking motivation and the processing of social cues. Overall, our brain-wide investigation highlighted that different pleiotropic mechanisms likely contribute to the relationship of brain structure and function with alcohol drinking and tobacco smoking, suggesting decision-making activities and chemosensory processing as modulators of propensity towards alcohol and tobacco consumption.

Efficacy of Normalising Serum Zinc Level for Patients with Olfactory Dysfunction and Zinc Deficiency

INTRODUCTION

Zinc deficiency may worsen the severity of olfactory dysfunction; however, the relationship between serum zinc levels and therapeutic effects on olfactory dysfunction remains uncertain. This study investigated the relationship between normalising serum zinc levels and the therapeutic effects on olfactory dysfunction.

METHODS

Forty-two patients diagnosed with post-infectious, post-traumatic, and idiopathic olfactory dysfunction, with serum zinc levels <70 μg/dL, were included in the study. All patients were treated with mecobalamin, tokishakuyakusan, and polaprezinc. The patients were divided into 2 groups: the zinc-normalised (≥70 μg/dL) and zinc-deficient (<70 μg/dL) groups, based on their post-treatment serum zinc levels. Olfactory test results were compared in each of the 2 groups.

RESULTS

The patients were treated for a median of 133 days. The zinc-normalised group had significantly better results in all olfactory tests (detection/recognition thresholds of the T&T olfactometer, odour identification test (Open Essence), Visual Analogue Scale for olfactory dysfunction, and self-administered odour questionnaire). In contrast, only the self-administered odour questionnaire showed a significant improvement in the zinc-deficient group, with no significant differences observed in the other olfactory tests. When comparing the changes in the olfactory test scores between the 2 groups, significant differences were observed in the detection/recognition thresholds of the T&T olfactometer test and Open Essence results.

CONCLUSION

These findings suggest that patients with olfactory dysfunction may have difficulty improving their olfactory function if they also have zinc deficiency. Furthermore, normalisation of zinc deficiency may contribute to the improvement of olfactory dysfunction with general treatment.

Olfactory deficit: a potential functional marker across the Alzheimer's disease continuum

Alzheimer's disease (AD) is a prevalent form of dementia that affects an estimated 32 million individuals globally. Identifying early indicators is vital for screening at-risk populations and implementing timely interventions. At present, there is an urgent need for early and sensitive biomarkers to screen individuals at risk of AD. Among all sensory biomarkers, olfaction is currently one of the most promising indicators for AD. Olfactory dysfunction signifies a decline in the ability to detect, identify, or remember odors. Within the spectrum of AD, impairment in olfactory identification precedes detectable cognitive impairments, including mild cognitive impairment (MCI) and even the stage of subjective cognitive decline (SCD), by several years. Olfactory impairment is closely linked to the clinical symptoms and neuropathological biomarkers of AD, accompanied by significant structural and functional abnormalities in the brain. Olfactory behavior examination can subjectively evaluate the abilities of olfactory identification, threshold, and discrimination. Olfactory functional magnetic resonance imaging (fMRI) can provide a relatively objective assessment of olfactory capabilities, with the potential to become a promising tool for exploring the neural mechanisms of olfactory damage in AD. Here, we provide a timely review of recent literature on the characteristics, neuropathology, and examination of olfactory dysfunction in the AD continuum. We focus on the early changes in olfactory indicators detected by behavioral and fMRI assessments and discuss the potential of these techniques in MCI and preclinical AD. Despite the challenges and limitations of existing research, olfactory dysfunction has demonstrated its value in assessing neurodegenerative diseases and may serve as an early indicator of AD in the future.

The combination of olfactory dysfunction and depression increases the risk of incident dementia in older adults

OBJECTIVES

Olfactory dysfunction and depression are common in later life, and both have been presented as risk factors for dementia. Our purpose was to investigate the associations between these two risk factors and determine if they had an additive effect on dementia risk.

DESIGN

Olfactory function was assessed using the Brief Smell Identification Test (BSIT), and depression was classified using a combination of the 15-item Geriatric Depression Scale (GDS) score and current antidepressant use. Cross-sectional associations between depression and olfactory function were examined using correlations. Cox regression analyses were conducted to examine the longitudinal relationship between olfaction and depression and incident dementia across 12-years of follow-up.

PARTICIPANTS

Participants were 780 older adults (aged 70-90 years; 56.5% female) from the Sydney Memory and Ageing Study (MAS) without a diagnosis of dementia at baseline.

RESULTS

Partial correlation revealed a nonsignificant association between baseline depression and olfactory function after accounting for covariates (r = -.051, p = .173). Cox regression showed that depression at baseline (hazard ratio = 1.706, 95% CI 1.185-2.456, p = .004) and lower BSIT scores (HR = .845, 95%CI .789-.905, p < .001) were independently associated with a higher risk of incident dementia across 12 years. Entering both predictors together improved the overall predictive power of the model.

CONCLUSIONS

Lower olfactory identification scores and depressive symptoms predict incident dementia over 12 years. The use of BSIT scores and depression in conjunction provides a greater ability to predict dementia than either used alone. Assessment of olfactory function and depression screening may provide clinical utility in the early detection of dementia.

Evaluation of the NIH Toolbox Odor Identification Test across normal cognition, amnestic mild cognitive impairment, and dementia due to Alzheimer's disease

INTRODUCTION

Olfactory decline is associated with cognitive decline in aging, amnestic mild cognitive impairment (aMCI), and amnestic dementia associated with Alzheimer's disease neuropathology (ADd). The National Institutes of Health Toolbox Odor Identification Test (NIHTB-OIT) may distinguish between these clinical categories.

METHODS

We compared NIHTB-OIT scores across normal cognition (NC), aMCI, and ADd participants (N = 389, ≥65 years) and between participants positive versus negative for AD biomarkers and the APOE ε4 allele.

RESULTS

NIHTB-OIT scores decreased with age (p < 0.001) and were lower for aMCI (p < 0.001) and ADd (p < 0.001) compared to NC participants, correcting for age and sex. The NIHTB-OIT detects aMCI (ADd) versus NC participants with 49.4% (56.5%) sensitivity and 88.8% (89.5%) specificity. NIHTB-OIT scores were lower for participants with positive AD biomarkers (p < 0.005), but did not differ based on the APOE ε4 allele (p > 0.05).

DISCUSSION

The NIHTB-OIT distinguishes clinically aMCI and ADd participants from NC participants.

HIGHLIGHTS

National Institutes of Health Toolbox Odor Identification Test (NIHTB-OIT) discriminated normal controls from mild cognitive impairment. NIHTB-OIT discriminated normal controls from Alzheimer's disease dementia. Rate of olfactory decline with age was similar across all diagnostic categories. NIHTB-OIT scores were lower in participants with positive Alzheimer's biomarker tests. NIHTB-OIT scores did not differ based on APOE genotype.

Consistent social odor representation across 7 languages: the Social Odor Scale translation and validation

The Social Odor Scale (SOS) is a 12-item questionnaire initially developed and validated in Italian and German to investigate self-reported awareness of social odors, which are odors emanating from the human body that convey diverse information and evoke various emotional responses. The scale includes a total score and 3 subscales representing social odors in the respective categories: romantic partner, familiar, and strangers. Here, we aimed to (i) replicate the validation of the Italian and German versions of the SOS, (ii) translate and validate the SOS into multiple additional languages (French, English, Dutch, Swedish, Chinese), and (iii) explore whether the factor structure of each translated version aligns with the original versions. Confirmatory Factor Analysis (CFA) supported the scale's structure, yielding a good fit across all languages. Notable differences in SOS mean scores were observed among the different languages: Swedish participants exhibited lower social odor awareness compared to the other groups, whereas Chinese participants reported higher social odor awareness compared to Dutch and Swedish participants. Furthermore, SOS scores correlated with respondents' geographical location, with higher (i.e. northern) latitudes linked to lower social odor awareness. These results corroborate the SOS as a valid and reliable instrument, especially for the SOS total score and the Familiar and Partner factors, emphasizing the influence of individual and geographic factors on social odor awareness.

Olfactory Dysfunction Associated with Cognitive Decline in an Elderly Population

BACKGROUND

In many neurological disorders, including Alzheimer disease, early olfactory dysfunction is observed.

OBJECTIVE

In order to determine if deficits in olfactory memory are present in the elderly and if olfactory dysfunction correlates with cognitive impairment in the aging population, olfactory testing has been done on seniors from the NuAge cohort accepting to participate in the Olfactory Response Cognition and Aging (ORCA) secondary sub-study. The t-Mini Mental Statement Examination and the Telephone Interview for Cognitive Status tests were done to assess cognition levels.

RESULTS

Overall, 94% of the ORCA cohort displayed olfactory dysfunction. Deficits in olfactory memory were also present. A correlation was observed between olfactory function and cognitive test scores. Moreover, in women who smoked, there was an association between olfactory memory and cognitive scores.

CONCLUSION

Our results suggest that olfactory dysfunction may predict impending cognitive decline and highlights the need for olfactory training in seniors to improve olfaction and overall well-being.

Systematic replication of smoking disease associations using survey responses and EHR data in the All of Us Research Program

OBJECTIVE

The All of Us Research Program (All of Us) aims to recruit over a million participants to further precision medicine. Essential to the verification of biobanks is a replication of known associations to establish validity. Here, we evaluated how well All of Us data replicated known cigarette smoking associations.

MATERIALS AND METHODS

We defined smoking exposure as follows: (1) an EHR Smoking exposure that used International Classification of Disease codes; (2) participant provided information (PPI) Ever Smoking; and, (3) PPI Current Smoking, both from the lifestyle survey. We performed a phenome-wide association study (PheWAS) for each smoking exposure measurement type. For each, we compared the effect sizes derived from the PheWAS to published meta-analyses that studied cigarette smoking from PubMed. We defined two levels of replication of meta-analyses: (1) nominally replicated: which required agreement of direction of effect size, and (2) fully replicated: which required overlap of confidence intervals.

RESULTS

PheWASes with EHR Smoking, PPI Ever Smoking, and PPI Current Smoking revealed 736, 492, and 639 phenome-wide significant associations, respectively. We identified 165 meta-analyses representing 99 distinct phenotypes that could be matched to EHR phenotypes. At P < .05, 74 were nominally replicated and 55 were fully replicated. At P < 2.68 × 10-5 (Bonferroni threshold), 58 were nominally replicated and 40 were fully replicated.

DISCUSSION

Most phenotypes found in published meta-analyses associated with smoking were nominally replicated in All of Us. Both survey and EHR definitions for smoking produced similar results.

CONCLUSION

This study demonstrated the feasibility of studying common exposures using All of Us data.

Differences in olfactory dysfunction and its relationship with cognitive function in schizophrenia patients with and without auditory verbal hallucinations

Olfactory discrimination dysfunction has been observed in patients with schizophrenia (SCZ), but its relationship with cognitive function has not been clarified. The purpose of this study was to examine the differences in olfactory identification function in SCZ patients with and without auditory verbal hallucinations (AVHs) and its relationship with cognitive function. Olfactory identification function was measured in 80 SCZ patients with AVHs, 57 SCZ patients without AVHs, and 87 healthy controls (HC). Clinical symptom scores and neuropsychological measures were also administered to all corresponding subjects. Compared to HC, SCZ patients showed significant deficits in olfactory identification and cognitive function, but there were no differences in olfactory identification dysfunction and cognitive dysfunction between the two subgroups. In the non-AVHs subgroup only, poorer Olfactory Stick Identification Test for Japanese (OSIT-J) scores were significantly and positively correlated with total and delayed recall (Bonferroni correction, p < 0.002). Stepwise regression analysis revealed that factors affecting olfactory identification impairment differed in the two SCZ patient subgroups. In conclusion, this study highlights the commonality of olfactory identification dysfunction in SCZ patients and the importance of olfactory assessment of different subtypes of SCZ patients.

Alcohol cue reactivity in the brain: Age-related differences in the role of social processes in addiction in male drinkers

Social attunement (SA)-the tendency to harmonize behavior with the social environment-has been proposed to drive the escalation of alcohol use in adolescence, while reducing use in adulthood. Little is known about how heightened social sensitivity in adolescence may interact with neural alcohol cue reactivity-a marker of alcohol use disorder-and its relationship to alcohol use severity over time. The aims of this study were to test whether (1) adolescents and adults differ in social alcohol cue reactivity in the nucleus accumbens, anterior cingulate cortex, and right medial prefrontal cortex (mPFC), and (2) age moderates the relationship between social alcohol cue reactivity and social attunement, measures of drinking at baseline, and changes in drinking over time. A sample of male adolescents (16-18 years) and adults (29-35 years) completed an fMRI social alcohol cue-exposure task at baseline and an online follow-up two to three years later. No main effects of age or drinking measures were observed in social alcohol cue reactivity. However, age significantly moderated associations of social alcohol cue reactivity in the mPFC and additional regions from exploratory whole-brain analyses with SA, with a positive association in adolescents and negative association in adults. Significant age interactions emerged only for SA in predicting drinking over time. Adolescents with higher SA scores escalated drinking, while adults with higher SA scores reduced drinking. These findings warrant further research on SA as a risk and protective factor and suggest that social processes influence cue reactivity differentially in male adolescents and adults.

Factors Associated with Poor Olfaction and Olfactory Decline in Older Adults in the ARIC Neurocognitive Study

Olfactory function has significant implications for human health, but few risk factors for olfactory decline have been identified. We examined the factors associated with olfactory status and decline over five years in the Atherosclerosis Risk in Communities (ARIC) Neurocognitive Study. A 12-item odor identification test was used to assess olfaction in 6053 participants in 2011-2013 (ARIC visit 5, mean age: 75.6, 41% male, 23% Black race) and in 3235 participants in 2016-2017 (visit 6). We used Poisson regression models to examine cross-sectional associations of a range of potential factors with the total odor identification errors (mean errors: 2.8 ± 2.4) in visit 5 participants. We used mixed-effect Poisson regression to examine associations with olfactory decline between visits 5 and 6. We also examined associations with visit 5 anosmia prevalence (847 cases, 14%) and incident anosmia between the two visits (510 cases, 16%) using Poisson models. Older age, male sex, lower education, Black race, APOE ε4 alleles, and diabetes were associated with higher odor identification errors and higher anosmia prevalence, and greater physical activity and hypertension with better olfaction. Age, male sex, lower education, Black race, APOE ε4 allele, and vitamin B12 levels were associated with incident anosmia over 5 years. Older age was associated with faster olfactory decline. Future studies with longer follow-ups are warranted.

Ambient Air Pollutants and Olfaction among Women 50-79 Years of Age from the Sister Study

BACKGROUND

Poor olfaction is common in older adults and may have profound adverse implications on their health. However, little is known about the potential environmental contributors to poor olfaction.

OBJECTIVE

We investigated ambient fine particulate matter [PM ≤ 2.5 μ m in aerodynamic diameter (PM 2.5 )] and nitrogen dioxide (NO 2 ) in relation to poor olfaction in middle-aged to older women.

METHODS

The Sister Study is a nationwide cohort of 50,884 women in the United States with annual average air pollutant exposures estimated based on participants' residences from enrollment (2003-2009) through 2017. This analysis was limited to 3,345 women, 50-79 years of age as of January 2018, who completed the Brief Smell Identification Test (B-SIT) in 2018-2019. Poor olfaction was defined as a B-SIT score of ≤ 9 in the primary analysis. We conducted multivariable logistic regressions, accounting for covariates and study sampling design.

RESULTS

Overall, we found little evidence for associations of air pollutants with poor olfaction. The odds ratio (OR) and 95% confidence interval (CI) of poor olfaction for each interquartile range (IQR) increment of air pollutants in 2006 were 1.03 (95% CI: 0.91, 1.17) for PM 2.5 (per 3.3   μ g / m 3 ) and 1.08 (95% CI: 0.96, 1.22) for NO 2 (per 5.7  ppb ). Results were similar in the analyses using the most recent (2017) or the cumulative average (2006-2017) air pollutant exposure data. Secondary analyses suggested potential association in certain subgroups. The OR per IQR was 1.35 (95% CI: 1.11, 1.65) for PM 2.5 among younger participants (< 54.2 years of age) and 1.87 (95% CI: 1.29, 2.71) for NO 2 among current smokers.

DISCUSSION

This study did not find convincing evidence that air pollutants have lasting detrimental effects on the sense of smell of women 50-79 years of age. The subgroup analyses are exploratory, and the findings need independent confirmation. https://doi.org/10.1289/EHP12066.

Indoor Air Quality-An Overview of Methods for Measuring Odor Detection Thresholds of Single Substances

Odor evaluation is an important topic in the field of indoor air quality. Odor detection threshold (ODT) values are used to derive limit values like odor guide values or odor activity value. However, ODT values for the same substance available in compilations or published before 2003 rarely have an accuracy of less than three orders of magnitude. Stimulus preparation, including analytical verification, stimulus presentation, as well as selection and training of test subjects have been identified as major sources of variability. ODT values obtained by validated standardized methods are now considered objective, reliable, and reproducible. They exhibit a variability of one or two orders of magnitude and are lower than traditionally assumed and reported. This review presents the essential criteria for a well-performed ODT determination. It is intended to assist health and safety professionals in assessing whether the methodological approach of a study was appropriate for determining a valid and reliable ODT value.

Is Olfactory Testing a Useful Diagnostic Tool to Identify SARS-CoV-2 Infections Early? A Cross-Sectional and Longitudinal Analysis

BACKGROUND

Genesis and the prognostic value of olfactory dysfunction (OD) in COVID-19 remain partially described. The objective of our study was to characterize OD during SARS-CoV-2 infection and to examine whether testing of OD may be a useful tool in clinical practice in order to early identify patients with SARS-CoV-2 infection.

METHODS

Olfactory function assessment was objectively carried out using the u-Smell-it^® test. In a cross-sectional study part, we evaluated this test in a control cohort of SARS-CoV-2 negative tested patients, who attended the University Hospital Frankfurt between May 2021 and March 2022. In a second longitudinal study part, sensitivity and specificity of OD was evaluated as a diagnostic marker of a SARS-CoV-2 infection in Frankfurt am Main, Germany in SARS-CoV-2 infected patients and their close contacts.

RESULTS

Among 494 SARS-CoV-2 negative tested patients, OD was detected in 45.7% and was found to be significantly associated with the male gender (p < 0.001), higher age (p < 0.001), cardiovascular and pulmonary comorbidities (p < 0.001; p = 0.03). Among 90 COVID-19 positive patients, OD was found in 65.6% and was significantly associated with male gender and positive smoking status (p = 0.04 each). Prevalence and severity of OD were significantly increased in infections with the Delta variant (B.1.617.2) compared to those with the Omicron variant (BA.1.1.529). Diagnostic sensitivity and specificity of OD for diagnosis of SARS-CoV-2 infection were 69% and 64%, respectively.

CONCLUSION

OD is common in COVID-19 negative and positive tested patients with significantly different prevalence rates observed between different variants. Diagnostic accuracy of OD is not high enough to implement olfactory testing as a tool in diagnostic routine to early identify patients with a SARS-CoV-2 infection.

The effects of cognition, quality of life, and fatigue on olfactory function in patients with multiple sclerosis

AIM

The frequency of olfactory dysfunction in patients with Multiple Sclerosis (MS) has revealed very different results in studies. Some studies have shown that olfactory dysfunction may be associated with cognitive impairment and poor quality of life. In these studies, different odor tests and cognitive tests were used and different results were obtained.

MATERIALS AND METHODS

Forty literate patients over the age of 18 and 24 healthy volunteers of similar age and education were included in the study. Sniffin' Sticks Odor Test, California Verbal Learning Test II, Symbol Digit Modalities Test, Revised Brief Visuospatial Memory Test, Trail-Making Test, Quality of Life Short Form-36, Fatigue Impact Scale, Beck Depression Inventory, and Beck Anxiety Inventory were applied to the individuals.

RESULTS

Olfactory dysfunction was detected in 50 % of the patients. High disability rate, low cognitive functions, low quality of life, and fatigue were identified as the factors affecting olfactory function negatively. Odor discrimination and identification abilities were associated with disability level and cognitive functions, whereas quality of life was linked to odor threshold scores. The olfactory function and cognitive abilities of patients with progressive MS (n = 5) were worse than those of patients with relapsing remitting MS (n = 35).

CONCLUSION

Olfactory dysfunction is common in patients with MS and is associated with disability and quality of life. Olfactory function can be used in the follow-up of patients and olfactory dysfunction deserves further study as a metric that might emerge as a biomarker.

Deficits in peripheric and central olfactory measurements in smokers: evaluated by cranial MRI

OBJECTIVES

Cigarette smoking remains a serious health problem all over the world. We investigated the peripheral and central olfactory pathways in young male smokers to determine whether there is a relationship between the amount of cigarettes smoked and duration of smoking and the dimensions of the olfactory areas.

METHODS

In this retrospective study, cranial Magnetic Resonance Imaging (MRI) images of adult male smokers aged ≤ 40 years (n = 51) and 50 healthy male adults were analyzed. The olfactory bulbus (OB) volumes and olfactory sulcus (OS) depths, insular gyrus, and corpus amygdala areas were measured via cranial MRI. In the smoker group, the number of cigarettes smoked and duration of smoking were noted and the Brinkmann index was calculated.

RESULTS

OB volume, OS depth, and the insular gyrus areas of the smokers were lower than in the control group (p < 0.05). There were no differences between the groups in terms of the corpus amygdala measurements (p > 0.05). No significant correlations were found between the number of cigarettes smoked daily, smoking duration, and the Brinkmann index and the peripheral and central olfactory measurements in our study (p > 0.05).

CONCLUSIONS

In smokers, OB volumes, the OS, and the central areas decrease bilaterally, regardless of smoking duration and number of cigarettes smoked daily. This could be related to inflammatory mediators that may be harmful to the olfactory neuroepithelium, gray matter atrophy in the brain, or endothelial damage related to smoking and its effects on blood support to the brain and olfactory regions.

The impact of age on olfactory alcohol cue-reactivity: A functional magnetic resonance imaging study in adolescent and adult male drinkers

BACKGROUND

Adolescence is marked not only by rapid surges in the prevalence of alcohol use disorders (AUDs) but also by remarkable recovery rates, as most adolescent-onset AUDs naturally resolve over time. Little is known about the differential vulnerability of adolescents and adults. Therefore, this study aimed to unravel the moderating role of age by comparing neural alcohol cue-reactivity, an important AUD biomarker, between low-to-high beer-drinking adolescent (n = 50, 16 to 18 years), and adult (n = 51, 30 to 35 years) males matched on drinking severity.

METHODS

Associations between beer odor-induced brain activity and AUD diagnosis, severity of alcohol use-related problems, recent alcohol use, binge-drinking frequency, and task-induced craving were investigated across and between age groups in regions of interest thought to be central in alcohol cue-reactivity: the medial prefrontal cortex, anterior cingulate cortex, and striatal subregions (nucleus accumbens and caudate putamen). These analyses were complemented by exploratory whole-brain analyses.

RESULTS

Pre-task beer craving increased pre-to-post task in adolescents only. Individual differences in alcohol use, binge drinking, and craving did not relate to beer odor-induced activity. Although region-of-interest analyses did not reach significance, whole-brain analyses showed that adolescents with AUD, compared with adolescents without AUD and adults with AUD, had higher beer odor-induced activity in a large mesocorticolimbic cluster encompassing the right caudate, nucleus accumbens, orbitofrontal cortex, and the olfactory sulcus. Activity in the right caudate and putamen was positively associated with the severity of alcohol use-related problems in adolescents but negatively associated in adults.

CONCLUSION

These findings suggest a differential role of alcohol cue-reactivity in adolescents compared with adults with AUD and highlight the need for further studies investigating the role of age in the fundamental processes underlying the development of and recovery from of AUD.

Relationship between the severity of olfactory dysfunction and serum zinc levels

PURPOSE

Although the association between zinc deficiency and olfactory dysfunction is inconclusive, zinc deficiency causes apoptosis of the olfactory ensheathing cells which is involved in olfactory nerve turnover and axon regeneration, thereby suggesting a possible relationship. We investigated the relationship between serum zinc levels and olfactory function in patients with olfactory dysfunction.

METHODS

Ninety patients who had been diagnosed with post-infectious, posttraumatic, drug-induced, neurological and idiopathic olfactory dysfunction were included. Patients were divided into zinc normal group and zinc deficiency groups according to three reference values for serum zinc levels (60, 65, 70 µg/dL). The results of olfactory tests and patient backgrounds were used to compare the differences between the two groups.

RESULTS

There were significantly worse detection and recognition thresholds in the T&T olfactometer and Open Essence (odor identification test) results in the zinc deficiency group (< 60 µg/dL). In addition, significant correlations between olfactory tests (detection/recognition thresholds in the T&T olfactometer and Open Essence results) and serum zinc levels < 65 µg/dL were observed. The zinc deficiency group < 70 µg/dL with idiopathic olfactory dysfunction had significantly worse olfactory tests (detection/recognition thresholds in the T&T olfactometer and Open Essence). In addition, there was a significant correlation between the detection/recognition thresholds in the T&T olfactometer and serum zinc levels in idiopathic olfactory dysfunction.

CONCLUSIONS

Our findings suggest that zinc deficiency may exacerbate the severity of olfactory dysfunction. Furthermore, idiopathic olfactory dysfunction may be partly caused by zinc deficiency.

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.

Olfaction in (Social) Context: The Role of Social Complexity in Trajectories of Older Adults' Olfactory Abilities

Objectives: Olfaction is an important correlate of later-life health, including cognition and mortality risk. Environmental enrichment protects against olfactory decline, yet little research considers the social context as a source of sensory enrichment or stimulation. This study examines how exposure to social complexity (i.e., diversity or novelty in social networks and activities) shapes later-life olfaction. Methods: Cross-sectional and longitudinal ordered logit models analyze data from 1,447 older adults interviewed at Rounds 1 and 2 of the National Social Life, Health, and Aging Project. Results: Exposure to greater social complexity (larger social networks, greater network diversity) is associated with significantly better olfaction at baseline. Increases in network diversity and fewer network losses significantly protect against olfactory decline over time. Discussion: Findings highlight the social context as an important, yet relatively overlooked source of sensory enrichment, and underscore the need for biological applications to integrate social life dynamics into studies of health trajectories.

Evaluation of the intensity of cigarette odors based on the perception of consumers

INTRODUCTION

We evaluated the tobacco odor intensity of cigarettes based on a large consumer panel and explored the differences of odor intensity perception based on sex, age and smoking habits.

METHODS

The perceived intensity of tobacco odor of cigarettes was evaluated using a consumer group method. A consumer panel of 240 volunteers (80 smokers, 80 ex-smokers and 80 non-smokers) was asked to smell eleven unlit cigarettes and then report their tobacco odor intensity in a specific questionnaire.

RESULTS

All volunteers clearly determined the presence of tobacco odor in all cigarettes. There is a general decrease of the perceived odor intensity with age, for both males and females. Moreover, tobacco odor perceived intensity, among all volunteer groups (smokers, non-smokers, ex-smokers), was higher for females than for males. Non-smokers declared the highest perceived tobacco odor intensities, followed by ex-smokers and smokers, who recorded the lowest perceived odor intensity. Perceived odor intensity decreased with age, with a higher rate for females compared to males, but independently of the smoking habits.

CONCLUSIONS

Regular and untrained consumers confirmed that a tobacco odor of different intensity can be perceived during the smelling of unlit cigarettes. This perceived intensity depends on sex, age and smoking habits.

Wearing N95 masks decreases the odor discrimination ability of healthcare workers: a self-controlled before-after study

Objective

During the coronavirus disease 2019 (COVID-19) pandemic, the N95 mask is an essential piece of protective equipment for healthcare workers. However, the N95 mask may inhibit air exchange and odor penetration. Our study aimed to determine whether the use of N95 masks affects the odor discrimination ability of healthcare workers.

Methods

In our study, all the participants were asked to complete three olfactory tests. Each test involved 12 different odors. The participants completed the test while wearing an N95 mask, a surgical mask, and no mask. The score for each olfactory test was documented.

Results

The olfactory test score was significantly lower when the participants wore N95 masks than when they did not wear a mask (7 vs. 10, p < 0.01). The score was also lower when the participants wore N95 masks than surgical masks (7 vs. 8, p < 0.01).

Conclusion

Wearing N95 masks decreases the odor discrimination ability of healthcare workers. Therefore, we suggest that healthcare workers seek other clues when diagnosing disease with a characteristic odor.

Inaccurate self-report of olfactory dysfunction in REM Sleep Behaviour Disorder and implications for prognosis

Introduction

The earliest stages of alpha-synucleinopathies are accompanied by non-specific prodromal symptoms such as diminished sense of smell, constipation and depression, as well as more specific prodromal conditions including REM Sleep Behaviour Disorder (RBD). While the majority of RBD patients will develop an alpha-synucleinopathy, one of the greatest clinical challenges is determining whether and when individual patients will phenoconvert. Clinical evaluation of a patient presenting with RBD should therefore include robust and objective assessments of known alpha-synucleinopathy prodromes.

Methods

This study compared olfactory function self-report measures with psychophysical 'Sniffin' Stick 16-item Identification' test scores in Control (n = 19), RBD (n = 16) and PD (n = 17) participants.

Results

We confirm that olfactory test scores are significantly diminished in RBD and PD groups compared to Controls (p < 0.001, One-Way ANOVA with Tukey-Kramer Post-Hoc, effect size = 0.401). However, RBD participants were only 56 % accurate when self-reporting olfactory dysfunction, hence markedly less likely to perceive or acknowledge their own hyposmia compared to Controls (p = 0.045, Fisher's Exact Test, effect-size = 0.35).

Conclusion

When isolated RBD presents with hyposmia, there is an increased likelihood of phenoconversion to Parkinson's Disease (PD) or Dementia with Lewy Bodies (DLB); unawareness of olfactory dysfunction in an individual with isolated RBD may therefore confound differential diagnosis and prognosis. Our results evidence the fallibility of olfactory function self-report in the context of RBD prognosis, indicating that clinical assessments of RBD patients should include more reliable measures of olfactory status.

Drug-Associated Parosmia: New Perspectives from the WHO Safety Database

Parosmia is a qualitative distortion of smell perception. Resulting from central causes, sinonasal diseases, and infections, parosmia has also been associated with medications. Therefore, we aimed to investigate potential signals for drugs associated with parosmia. VigiBase® (the WHO pharmacovigilance database) was queried for all reports of “Parosmia” (MedDRA Preferred Term), registered up to 23 January 2022. Disproportionality analysis relied on the reporting odds ratio and the information component. A signal is detected when the lower end of the 95% confidence interval of the information component is positive. We found 14,032 reports of parosmia, with a median patient age of 53 years. Most reported drugs were antiinfectives, among which COVID-19 vaccines accounted for 27.1% of reports. Antibiotics and corticosteroids were involved in 6.8% and 4.6% of reports. Significant disproportionate reporting was detected for corticosteroids, antibiotics, drugs used in nicotine dependence, COVID-19 and HPV vaccines, serotonin–norepinephrine reuptake inhibitors (SNRI), and incretin mimetics. We suggest potential safety signals involving nicotine replacement therapies and vaccines. We also highlight the potential role of less suspected classes, such as SNRIs and incretin mimetics. An iatrogenic etiology should be evoked when parosmia occurs, especially in the elderly.

Something Stinks! Finding Ways to Manage Noxious Odours in the Operating Room and Other Clinical Settings A Randomized Controlled Trial

Objectives: The hospital can be saturated with noxious smells. Anecdotally, medical staff apply products to surgical masks to lessen the impact of these smells. This study aimed to determine the odour-masking ability of 4 inexpensive and convenient products. Methods: A randomized, single-blinded crossover study was conducted in Vancouver, Canada. Participants, 19 to 30 years old, were invited to participate. Participants with active allergies, upper respiratory tract infection, alteration to sense of smell, or failure of olfactory screen were excluded from the study. An experimental odour was used in lieu of a noxious surgical odour. After smelling the experimental odour without barriers, participants were re-exposed to the odour using 5 surgical masks in randomized order. Each mask was lined with a test product (cherry lip balm, tincture of benzoin, Mastisol, mint toothpaste, and control [plain mask]). Participants rated the effectiveness of products at masking the experimental odour from 0 to 100 (0 = completely ineffective, 100 = completely effective). Participants also rated the pleasantness of the products, recorded if the products made them feel unwell, and identified their preferred product overall. Results: Eighty participants were included in the study (33 male, 47 female), averaging 24.2 years of age. Mean odour-masking effectiveness for cherry lip balm was 66.5 (±24.6), tincture of benzoin: 62.6 (±25.0), Mastisol: 61.3 (±23.9), mint toothpaste: 57.5 (±27.4), and control: 21.9 (±21.8). All products performed better than the control (P < .001), but there was no significant difference in performance between products. Cherry lip balm was the most preferred odour-masking product (29 participants), followed by mint toothpaste (22), Mastisol (14), tincture of benzoin (10), and control (5). Conclusions: All tested products demonstrated equivalent odour-masking abilities. If health care professionals choose to use an odour-masking product, they should consider their own olfactory preferences.

Total laryngectomy negatively impacts sinonasal and olfactory-specific quality of life

PURPOSE

The purpose of this study is to characterize deficits in olfactory-specific and sinonasal-specific QoL after total laryngectomy (TL) with validated patient reported outcome measures.

METHODS

Thirty patients who had a TL were prospectively enrolled. Patient demographics, as well as scores from the Questionnaire of Olfactory Disorders Negative Statements (QOD-NS) and the Sino-nasal Outcome Test-22 (SNOT-22) were collected. Univariate analysis was performed to assess associations between patient characteristics and QoL scores.

RESULTS

The average QOD-NS score was 37.9 ± 11.4 (<38.5 is considered abnormal) and average SNOT-22 score was 32.0 ± 3.8 (>20 indicates a moderate/severe impact on QoL). The abnormal QOD-NS group had a greater percentage of former smokers compared to the normal group (77.8% vs. 58.1%; P = 0.56) and more median days from surgery compared to the normal group (904 vs. 477 days; P = 0.24).

CONCLUSIONS

Olfactory dysfunction associated with TL results in blunting of olfactory-specific QoL.

Individual characteristics, including olfactory efficiency, age, body mass index, smoking and the sex hormones status, and food preferences of women in Poland

Background

Food choices made by most people mainly depend on food preferences. Knowing how certain factors affect food preferences can help dietitians working with women to understand the relationship between individual factors and the challenges faced by the women in changing eating habits. The aim of the study was to examine the food preferences of women and to assess the impact of the sense of smell, age, body mass index (BMI), smoking and hormonal status (phase of the menstrual cycle, hormonal contraception) on the declared pleasure derived from eating various types of food.

Methods

A total of 190 women living in the Górnośląsko-Zagłębiowska Metropolis in Poland aged 18-75 (19.29-26.71 RNO) years participated in the study. The collected survey data included age, BMI, smoking, phase of the menstrual cycle and hormonal contraception. Olfactory sensitivity was measured by T08 olfactometer. Additionally, food preferences were assessed, using 24 different food types, which were presented as pictures. To evaluate food preferences 10 cm visual analogue scale was used.

Results

The most liked foods were: fruits (M = 8.81, SD = 1.67), sweet desserts (M = 8.44, SD = 2.30), vegetables and salads (M = 8.08, SD = 2.24), chocolate (M = 7.84, SD = 2.76), and poultry (M = 7.30, SD = 2.47). The least liked foods were: salty products (M = 4.98, SD = 3.03), milk soup (M = 3.30, SD = 3.13), and seafood (M = 2.99, SD = 3.28). The influence of the analyzed factors on the degree of liking six food types was shown. Women with better ability to name scents preferred sausages/ham and beef/pork. Women with a higher BMI had lower preference for jellybeans and broth. Women who were heavier smokers had lower preference for milk soup. In women using hormonal contraception, pleasure from eating sausages and ham was higher than compared to women in all phases of the monthly cycle. In women in the follicular phase the pleasure from eating pasta was lower when compared to women in the ovulatory phase, the luteal phase and those using hormonal contraception. In women in the ovulatory phase the pleasure from eating candies and jellybeans was lower when compared to women in the follicular phase, the luteal phase and those using hormonal contraception. In women in the ovulatory phase, also pleasure from eating broth was lower when compared to women in the luteal phase and those using hormonal contraception.

Conclusions

Among women in Poland, the top five preferred food types are fruits, sweet desserts, vegetables/salads, chocolate and poultry. To confirm the extent to which the declared pleasure derived from eating these food types translates into health condition, further research on the consumption of these food types is necessary. The impact of the sense of smell, BMI, smoking, or menstrual cycle phase and hormonal contraception on the declared pleasure derived from eating was observed for six out of twenty-four food types. The hormonal status was the factor most significantly influencing food preferences.

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.

Measured and self-reported olfactory function in voluntary Norwegian adults

Purpose

The lack of epidemiological data on the proportion of olfactory dysfunction (OD) using comprehensive olfactory assessment in healthy adults in Scandinavia motivated to the present study which aimed to explore the proportion of OD in voluntary healthy Norwegian adults, assessed by Sniffin’ Sticks, and its correlation to self-reported olfactory function. Furthermore, sociodemographic and clinical factors associated with olfactory function were analysed.

Methods

The sample included 405 Norwegian participants, aged 18–78 years, 273 women and 132 men, who underwent olfactory testing with extensive Sniffin’ Sticks test, allergy testing, clinical examination with nasal endoscopy and completed a self-administered questionnaire, including self-evaluation of olfactory function on a 100 mm Visual Analogue Scale.

Results

We found that 37% had OD, of which 1.2% had anosmia assessed with extensive Sniffin’ Sticks test. The proportion of hyposmia and anosmia increased with age. Men and participants with low education had poorer olfactory function scores. Allergy, smoking status, general health and endoscopic findings were not associated with measured olfactory function. We found no correlation between self-reported and measured olfactory function.

Conclusions

This study has identified that a large proportion of our sample of voluntary healthy Norwegian adults have OD, considerably more common in older adults and somewhat more common in men and individuals with low education. The lack of correlation between self-reported and measured olfactory function highlights the importance of using validated tests for a reliable olfactory evaluation.

The Toronto Concussion Study: Sense of smell is not associated with concussion severity or recovery

OBJECTIVE

To examine sense of smell as a biomarker for both severity and duration of post-concussion symptoms.

METHODS

Participants were recruited prospectively from an outpatient concussion clinic. Sense of smell was assessed using the University of Pennsylvania Smell Identification Test (UPSIT) within 7 days, and 4, 8 - or 16-weeks post-injury. UPSIT normative data were used as normal controls. The main outcomes were: symptom severity on the Sport Concussion Assessment Tool 3 (SCAT3) symptom inventory and time to physician-declared recovery.

RESULTS

A total of 167 participants (mean age 32.9 [SD, 12.2] years, 59% female [n = 99]) were classified at 1 week post injury as follows: severe hyposmia in 5 (3%), moderate hyposmia in 10 (6%), mild hyposmia in 48 (29%), and normosmia in 104 (62%) individuals. A convenience sample of 81 individuals with concussion were tested at follow-up. Acute impairment of sense of smell following concussion was not associated with symptom severity on the SCAT3 or time to recovery. Sense of smell was stable from baseline to follow-up in this population.

CONCLUSION

This study provides evidence that routine testing of sense of smell in individuals with concussion is not warranted as a biomarker for severity of concussion and concussion recovery.

Environmental triggers of Parkinson's disease - Implications of the Braak and dual-hit hypotheses

Idiopathic Parkinson's disease (PD) may take decades to develop, during which many risk or protective factors may come into play to initiate the pathogenesis or modify its progression to clinical PD. The lack of understanding of this prodromal phase of PD and the factors involved has been a major hurdle in the study of PD etiology and preventive strategies. Although still controversial, the Braak and dual-hit hypotheses that PD may start peripherally in the olfactory structures and/or the gut provides a theoretical platform to identify the triggers and modifiers of PD prodromal development and progression. This is particularly true for the search of environmental causes of PD as the olfactory structures and gut are the major human mucosal interfaces with the environment. In this review, we lay out our personal views about how the Braak and dual-hit hypotheses may help us search for the environmental triggers and modifiers for PD, summarize available experimental and epidemiological evidence, and discuss research gaps and strategies.

Associations Between Cognitive Function, Depression, and Olfactory Function in Elderly People With Dementia in Korea

Early detection is important for delaying or preventing cognitive impairment. Since olfactory dysfunction and depression are common symptoms of cognitive dysfunction, they may serve as measurable risk indicators. This study was designed to identify the relationship between olfaction, depression, and each domain of cognitive function in elderly dementia patients in South Korea. Study participants were 108 patients who visited the outpatient clinic between March and September 2019. More significant impairment of olfactory function was found in those with mild (7.48 ± 1.28) or moderate (7.37 ± 2.22) test scores of the Expanded Clinical Dementia Rating (CDR) scale than in those with questionable scores (20.58 ± 6.18). The language domain of cognitive function, age, and education level showed 39.2% explanatory power for olfactory function (F = 5.591, p < 0.001). It is expected that assessment of olfactory function in elderly people can lead to the early detection, diagnosis, and treatment of dementia. Furthermore, it is important for future studies to confirm the relationship between each domain of cognitive function and olfactory function according to the type of dementia and to establish criteria for screening dementia in order to utilize olfactory function as a clinical marker.