Danish validation of sniffin' sticks olfactory test for threshold, discrimination, and identification

Accurate detection of pathologic α-synuclein in CSF, skin, olfactory mucosa, and urine with a uniform seeding amplification assay

Currently, early diagnosis of dementia with Lewy bodies (DLB) is based on clinical criteria, which is challenging due to overlapping symptoms with other neurodegenerative diseases. Seeding amplification assays, detecting minute amounts of disease causing α-synuclein (αSynD), are emerging as a promising diagnostic tool for α-synucleinopathies including DLB and Parkinson's disease. This study aimed to test whether the same seeding amplification assay established for αSynD detection in cerebrospinal fluid (CSF) could be applied to other biospecimens, including skin, olfactory mucosa, saliva, and urine, obtained from the same patients. A total of 31 patients with probable DLB and 53 healthy controls were recruited. When evaluating the assays' applicability to different biospecimens, only those collected from participants with a positive CSF αSynD result were considered. Seeding amplification assay results were evaluated based on the αSynD amplification rate over 48 h and the value of the area under the curve. The sensitivity and specificity were 94% and 98% for skin, 47% and 100% for olfactory mucosa, and 22% and 100% for urine, respectively for the CSF positive DLB and healthy controls. αSynD was undetectable in saliva. Cohen's Kappa analysis (κ) showed almost perfect agreement between CSF and skin assays (κ = 0.86) but slight to no agreement for CSF versus olfactory mucosa (κ = 0.12) and urine (κ = 0.094). In summary, the seeding amplification assay established for αSynD detection in CSF demonstrated comparable diagnostic performance in minimally invasive skin biopsies. Olfactory mucosa, saliva, and urine sample preparation pose technical challenges resulting in the established assays' low diagnostic accuracy, for now, limiting their use in diagnostics. Nevertheless, the proof-of-concept for αSynD detection in urine expands the potential for non-invasive diagnostics of α-synucleinopathies in the future.

Effect of Olfactory Training in COVID-19 Related Olfactory Dysfunction-A Placebo-Controlled Trial

OBJECTIVES

Olfactory training is a recommended treatment in patients with olfactory dysfunction after COVID-19. However, the effectiveness of olfactory training in COVID-19-induced olfactory dysfunction has been studied; only a few studies have included a placebo group to compare the effect of traditional olfactory training with odor-free olfactory training. In this randomized placebo-controlled trial, we evaluate the effect of olfactory training with essential oils versus olfactory training with placebo oils in patients with post-COVID-19 olfactory dysfunction.

METHODS

Sixty-five patients with COVID-19 induced olfactory dysfunction were randomized to the intervention or control group. Patients in the intervention group performed classic olfactory training with four essential oils (orange, lavender, clove, and peppermint) twice daily for 12 weeks, while the control group performed the same olfactory training but with odor-free placebo oils. Olfactory function was assessed using the Sniffin Sticks extended TDI test at baseline and at follow-up after the 12-week intervention.

RESULTS

The intervention group did not significantly improve their olfactory function compared to the control group after olfactory training. Additionally, no associations were found between changes in olfactory function after olfactory training and age, gender, rhinitis, time since infection, or pre-infection vaccine. A regression analysis showed that the presence of parosmia was associated with reduced effectiveness of olfactory training.

CONCLUSIONS

This study found that 12 weeks of classical olfactory training is not effective in the treatment of COVID-19 induced olfactory dysfunction. Moreover, the study indicates that parosmia reduces the effect of olfactory training significantly.

LEVEL OF EVIDENCE: 2

TRIAL REGISTRATION

Clinicaltrials.gov registration number: NCT05539560.

Statistical overview of the Sniffin' sticks olfactory test from the perspectives of anosmia and hyposmia

The Sniffin' Sticks test is evaluated by summing the scores of threshold, discrimination, and identification subtests to establish an olfactory diagnosis (anosmia, hyposmia, normosmia). However, variations in thresholds, ranges and inconsistencies have been observed. Statistical analyses (distributions, quantiles), protocol simulation, and implementations of the Sniffin' Sticks test were conducted. This study contributes a statistical revision: determining a cut-off point for the total TDI score, optimising the number of alternatives in the identification subtest, and equalising correct responses (frequency, balanced in time, subsequent pairs). The upper score threshold used to diagnose anosmia is lower than the typical first-order error thresholds applied in comparable assessments (anosmia ≤ 16.75 points, hyposmia ≥ 17 points at 90% confidence level). In the culturally adapted 16-pen Sniffin' Sticks identification tests, the frequency of correct responses was aligned with that of the original test. However, the equalisation of the frequency of adjacent correct response pairs and the temporal occurrence of correct responses was not met in any test. The order of all correct answers that simultaneously satisfied all three matching conditions was determined. The practical significance of the results is that the recommended protocol of the Sniffin' Sticks test system can be implemented in clinical practice with minimal modification.

Which is superior, the University of Pennsylvania Smell Identification Test or the threshold, Discrimination and Identification Test for testing human olfaction? A systematic review

BACKGROUND

The awareness and prevalence of olfactory dysfunction (OD) has increased significantly in recent years, with the SARS-CoV-2 pandemic being a major catalyzer. Consequently, demands for reliable OD tests have also risen.

AIMS

This systematic review compares two commonly used tests for olfactory assessment: the University of Pennsylvania Smell Identification Test (UPSIT) and the Threshold, Discrimination, and Identification test (TDI). The correlation between UPSIT, TDI, and the Visual Analogue Scale (VAS) for olfaction is also examined.

MATERIAL AND METHODS

A systematic search of PubMed and EMBASE identified articles validating UPSIT or TDI and comparing these to self-reported OD via VAS. The outcome of interest was test-retest validity and correlation.

RESULTS

The search identified 1536 studies, with nine meeting inclusion criteria. UPSIT showed a 'very strong' test-retest correlation, while TDI showed a 'strong' correlation. One study addressed VAS in relation to UPSIT and five for TDI. Correlation coefficients varied between VAS and TDI/UPSIT.

CONCLUSIONS AND SIGNIFICANS

UPSIT and TDI exhibited strong to very strong test-retest reliability. Due to the limited number of studies, a meta-analysis was not feasible, and neither test was found to be superior in reliability. VAS did not correlate significantly with either TDI or UPSIT.

Periodontitis is associated with impaired olfactory function: A clinical study

AIM

To explore the association between periodontitis and olfactory disorders.

METHODS

Clinical data were collected from 198 individuals between the ages of 18 and 60 years living in Denmark. The exposure was periodontitis, and the outcome was olfactory function (Threshold, Discrimination, Identification - TDI score), both measured clinically. Covariates included sex, age, education level, income, usage of nasal spray, tongue coating, halitosis, xerostomia, smoking, and history of COVID-19. Structural equation modeling was used to estimate the association between periodontitis and olfactory function. Periodontitis was defined using the AAP/EFP classification and dichotomized into "no" (healthy subjects) and "yes" (Stages I, II, and III). Olfactory function was treated as a one-factor latent variable, including the different olfactory scores. In addition, extra models were performed considering each olfactory component as a separate outcome and the TDI Global Score.

RESULTS

The results showed that periodontitis was associated with a lower olfactory function [standardized coefficient (SC) -0.264, 95% CI -0.401, -0.118]. Additionally, periodontitis was also associated with a lower olfactory Threshold (odorant concentration required for detection) (SC -0.207, 95% CI -0.325, -0.089), Discrimination (ability to discriminate between odorants) (SC -0.149, 95% CI -0.270, -0.027), Identification (ability to identify odorants) scores (SC -0.161, 95% CI -0.277, -0.045), and TDI Global Score (SC -0.234, 95% CI -0.370, -0.099).

CONCLUSIONS

This study suggests that periodontitis is associated with olfactory impairment.

Smell and taste disorders in childhood: Diagnostic challenges and significant impacts on a child's well-being

AIM

Smell and taste are senses that contribute to a child's overall well-being. Disorders affecting these senses can impact a child's daily life from enjoying meals to detecting potential dangers through scent. The aim of this study is to describe patient characteristics and etiological causes of olfactory (OD) and/or gustatory disorders (GD) in children referred to a smell and taste clinic. Secondly, we aim to suggest a clinical work up.

METHODS

Retrospective study where data were collected from 57 children who were referred consecutively to the University Clinic for Flavour, Balance, and Sleep; Department of Otorhinolaryngology (ORL), Head and Neck Surgery; Goedstrup Hospital, Denmark, for assessment due to OD/GD from January 2017 to May 2023.

RESULTS

Most of the children had anosmia (60 %), whereas sensation of the basic tastes was intact in all but eight children (16 %). The lowest TDI scores were in children with congenital OD. The underlying etiology was congenital followed by postinfectious mostly related to Covid-19. Picky eating including anorectic traits were seen in 16 % of patients.

CONCLUSION

The focus on smell loss in pediatric population is low, and probably does not adequately reflect either underlying prevalence in this group or the possible consequences on a child's well-being. Moreover, increased awareness of children's smell and taste loss is needed, as it may be associated with eating disturbances.

Using Cooking Schools to Improve the Pleasure of Food and Cooking in Patients Experiencing Smell Loss

Smell loss affects around 15-20% of the population, with a major effect on the quality of life. The most common complaint is the impairment of the eating experience, with around 90% of patients reporting this issue. A study conducted at a specialised Taste and Smell Clinic investigated if food and cooking can positively affect the enjoyment of food, subjective cooking skills, and quality of life in patients with smell loss. The 49 participants in the study received a 5-week cooking school course that focused on emphasizing the other senses to regain the enjoyment of food. Participants gained more confidence in cooking, and their quality of life improved significantly. Positively evaluated recipes were adjusted based on feedback and published as free e-books in Danish, German, and English. Eating and cooking are multisensory experiences, and the perception of food depends on the complex interaction of senses and surroundings. If the olfactory input is reduced or absent, both the enjoyment and cooking experience can be negatively affected. Therefore, focusing on food and cooking can have a positive impact on patients with smell loss.

Validation of Korean Olfactory Questionnaire for Perioperative Olfactory Assessment in Endoscopic Endonasal Skull Base Surgery

Objective: To analyze changes in olfactory function after endoscopic endonasal skull base surgery and compare performance of the olfactory questionnaire with those of conventional psychophysical tests. Methods: Patients were classified into 5 categories for olfactory function evaluation (normal, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia) based on a self-assessment. Patients also underwent the butanol threshold test (BTT), Cross-Cultural Smell Identification Test (CCSIT), and 11-item olfactory questionnaire. Subjects with normosmia preoperatively and who were followed up at least 6 months after surgery were analyzed. Receiver operating characteristic curves and confusion matrix analysis were performed for BTT, CCSIT, and olfactory questionnaire to compare their diagnostic abilities. The effects of age, preoperative olfaction, septal flap, tumor pathology, and tumor size on postoperative olfaction were evaluated using multivariate linear regression analysis. Results: Data from 108 patients were analyzed. Postoperative changes in the olfactory questionnaire were significantly associated with changes in the BTT and CCSIT. The area under the curve for postoperative self-olfactory function classification was highest for olfactory questionnaire (0.894), followed by BTT (0.767) and CCSIT (0.688). Patient age at the time of surgery and preoperative BTT score were significantly related to postoperative olfactory outcomes. Conclusion: The olfactory questionnaire correlated well with conventional psychosomatic olfactory function tests. In combination with clinical parameters and preoperative psychosomatic olfactory function tests, the olfactory questionnaire is suitable for assessing subjective olfactory function after endoscopic endonasal skull base surgery.

Post-COVID-19 patients suffer from chemosensory, trigeminal, and salivary dysfunctions

Recent literature indicates that post-COVID-19 patients suffer from a plethora of complications, including chemosensory dysfunction. However, little attention has been given to understand the interactions between chemosensory, trigeminal, and salivary dysfunctions in these patients. The aims of this study were (1) to investigate the prevalence and combinations of chemosensory, trigeminal, and salivary dysfunctions, (2) to identify the odorants/tastants that are compromised, and (3) to explore possible associations between the four dysfunctions in post-COVID-19 patients. One hundred post-COVID-19 patients and 76 healthy controls (pre-COVID-19) were included in this cross-sectional, case-controlled study. Participants' smell, taste, trigeminal, and salivary functions were assessed. The patients had a significantly higher prevalence of parosmia (80.0%), hyposmia (42.0%), anosmia (53.0%), dysgeusia (34.0%), complete ageusia (3.0%), specific ageusia (27.0%), dysesthesia (11.0%) and dry mouth (18.0%) compared to controls (0.0% for all parameters, except 27.6% for hyposmia). Complete loss of bitter taste was the most prevalent specific ageusia (66.7%) and coffee was the most common distorted smell (56.4%). Seven different combinations of dysfunction were observed in the patients, the most common being a combination of olfactory and gustatory dysfunction (48.0%). These findings indicate that post-COVID-19 patients experience a range of chemosensory, trigeminal, and salivary disturbances, occurring in various combinations.

Clinical utility of and correlation between Sniffin' Sticks and TIB smell identification test (TIBSIT) among Hong Kong Chinese with or without chronic rhinosinusitis

Introduction

Olfactory dysfunction (OD) is common among patients with chronic rhinosinusitis (CRS). Validated and culturally specific tests, such as the "Sniffin' Sticks" test (SST) and the TIB Smell Identification Test (TIBSIT), are crucial for the diagnosis and monitoring of OD. However, they have not been utilised in Hong Kong Chinese and their correlations are unknown.

Methods

Twelve CRS patients and twenty healthy volunteers were prospectively recruited from a joint allergy-otorhinolaryngology clinic in Hong Kong and performed both SST and TIBSIT. Demographics, baseline characteristics and all test results were compared and analysed.

Results

Patients with CRS demonstrated significantly lower test scores than healthy controls (all p < 0.001). Significant and strong correlations were observed between all composite and subtest scores, particularly between the composite SST and TIBSIT scores (ρ = 0.789, p < 0.001). Multivariate analysis demonstrated that the presence of CRS and increasing age were significantly associated with OD.

Conclusion

Both SST and TIBSIT are useful olfactory tests and are strongly correlated among Hong Kong Chinese. We advocate that either test can be used for measuring OD among CRS patients.

Psychometric validity of the sum score of the Sniffin' Sticks-Extended Test

A common tool to measure olfactory function is the Sniffin' Sticks Test extended version (SSET). The SSET evaluates olfactory ability by summing the scores of three subtests: Threshold, Discrimination, and Identification. Recent meta-scientific literature revealed that many psychometric instruments currently in use have not been adequately validated, leading to a measurement crisis that raises concerns about the validity of the conclusions drawn with these instruments. Two examples of the measurement crisis are (i) the use of sum scores without testing their assumptions (e.g. unidimensionality and tau-equivalence), which indicate that all subtests have the same, stable relationship with their underlying construct, and (ii) the lack of assessment of measurement invariance across groups. Here, we aim to investigate the unidimensionality and tau-equivalence assumptions, internal consistency, and measurement invariance of sex and age groups of the SSET. We tested 988 (555 females, mean ± SD: 39.75 ± 18.60 years) participants with the Italian version of the SSET. The tau-equivalent model demonstrated excellent fit indices (CFI robust = 1, TLI robust = 1, RMSEA robust = 0, SRMR = 0.013), which best explain the data, indicating that all subtests are equally important in measuring olfactory function, but not necessarily equally precise. The results also revealed full measurement invariance across age groups and configural, partial metric, and scalar invariance across sexes, indicating that the use of latent means to compare sex groups should be chosen over raw scores. However, the SSET demonstrated moderate internal consistency. Future studies should clarify whether the reliability of the SSET can be increased.

Odor familiarity and improvement of olfactory identification test in Chinese population

Aims

This study aimed to design the Chinese Modified Olfactory Identification (CMOI) test based on the Sniffin' Sticks Olfactory Identification (SSOI) test by changing unfamiliar distractors and odors for more familiar ones for the Chinese population.

Materials and methods

We recruited 200 healthy volunteers (103 males and 97 females, aged 18-65 years, mean age 35.04 years, SD 10.96); in a survey, 100 volunteers rated their familiarity with 121 odors, including all the SSOI test odor descriptors and common odors in Chinese daily life. The SSOI test was modified according to the survey results. The other 100 volunteers were tested three times using the SSOI test, the Modified Distractors Olfactory Identification (MDOI) test established by modifying distractors in the SSOI test, and the CMOI test developed by using familiar unpleasant odors to displace the odors with low correct recognition rates in the MDOI test. We compared the test scores of the volunteers during the modification process.

Results

Volunteers were unfamiliar with 31 odor descriptors in the SSOI test; 23 distractors with low familiarity were displaced with more familiar distractors. The three odors with the lowest correct recognition rate in the MDOI test (apple, leather, and pineapple) were displaced with familiar unpleasant odors. The test scores were significantly higher in the CMOI test than in others (p < 0.0001); the correct recognition rate in the CMOI test was significantly higher than in the SSOI test (p < 0.01).

Conclusion

The test scores in the CMOI test were significantly improved; it prevented choosing wrongly due to unfamiliarity with an odor and its distractors.

Reliability and validity of the Polish version of the Questionnaire of Olfactory Disorders

Background

The comprehensive counseling of patients with olfactory dysfunctions requires accurate diagnosis. The recommendations include subjective assessment. The Questionnaire of Olfactory Disorders (QOD) is a disease-specific questionnaire for the subjective evaluation of olfactory dysfunctions.

Material

The study included 54 patients with olfactory dysfunctions, who were recruited to the study group (SG). The other 47 patients without the history of olfactory dysfunction and nasal cavity pathology were voluntarily allocated to the control group (CG). The protocol of the study was introduced to each patient and included: olfactory testing with Sniffin' Stick test, fulfillment of the Polish version of World Health Organization Quality of Life brief questionnaire and completing of the Polish version of the QOD. All participants (101) were invited for refilling the QOD questionnaire after 2 weeks for the test-retest statistics.

Results

The Polish QOD statements were significantly correlated and met the requirement by having test-retest correlation larger than 0.7. We found that internal consistency of the test measured by Cronbach's alpha coefficient was very high. The mean scores of the QOD test in normosmic SG patients were compared with corresponding scores in normosmic CG patients using U Mann-Whitney test. The analysis revealed statistically significant differences on mean QOD scores for each domains except QOD-S between both groups.

Conclusions

The Polish version of the QOD demonstrated high rate of the validity and the reliability. This instrument may be widely used in research projects and clinical practice concerning olfactory disorders in Polish patients.

Level of Evidence

NA.

Cranial Nerve Affection in Adolescents with Type 1 Diabetes Assessed by Corneal Confocal Microscopy, Smell and Taste Tests

Aim

To determine whether adolescents with type 1 diabetes (T1D) have morphological changes of the corneal nerve fibers and reduced smell and taste function compared to healthy control subjects as a sign of cranial nerve affection and to evaluate possible associated risk factors for cranial nerve affection.

Methods

The study was a part of the T1DANES study including 60 adolescents (15-<19 years) and 23 healthy age-matched controls. First, clinical and biochemical data on the participants were obtained, and the second step involved a test day with neurological examinations including corneal confocal microscopy (CCM), olfactory testing with Sniffin' Sticks, and gustatory assessment with taste-drop test.

Results

The adolescents with T1D (mean diabetes duration 9.8 years, mean HbA1c 61 mmol/mol) had lower CCM parameters (corneal nerve fiber density, corneal nerve branch density, corneal nerve fiber length, and corneal nerve fiber fractal dimension) compared to control subjects (all p < 0.05). No differences in total score for smell test (p = 0.66) and taste test (p = 0.47) were found, but adolescents with T1D had reduced ability to taste sweet (p < 0.01). In total, 24% had two or more reduced CCM parameters, 12% had reduced smell test, and 23% had abnormal taste test. Higher waist to height ratio (WHtR) was the only risk factor found for reduced corneal nerve fiber density, and higher BMI-SDS and WHtR were found for impaired taste function. Having abnormal smell test increased the risk for having abnormal taste perception, and vice versa.

Conclusion

Up to 29% of adolescents with T1D had abnormal test scores indicating cranial nerve affection. Lower corneal nerve fiber density and reduced ability to taste sweet were found in adolescents with T1D compared to control subjects. Clinical attention to smell and taste function seems important because it requires intervention for advising adolescents with impaired smell and taste function.

Long-Term COVID-19 Smell and Taste Disorders Differ Significantly from Other Post-Infectious Cases

INTRODUCTION

COVID-19 is causing a wide range of clinical manifestations. Severe complications and long-lasting sequelae have been identified. Thus, olfactory disorders are reported in up to 86% of cases in mild and moderate COVID-19 infections. We present the first study comparing simple and complex post-COVID-19 cases with matched non-COVID-19 post-infectious smell and taste disorders.

METHODS

A total of 328 patients were recruited from the University Clinic for Flavour, Balance and Sleep, Ear-nose-throat Department, Goedstrup Hospital, Denmark. A non-COVID -19 post-infectious population of 148 individuals was identified from the Redcap database, and was matched by duration of smell and taste disorders. Post-COVID-19 patients were divided into 99 patients with simple smell and taste disorders (only suffering from smell and taste disorders after COVID-19); and (81 patients with complex smell and taste disorder plus several other post-COVID-19 complaints). Besides patient-reported outcome measures (PROM) questionnaires and quality of life score (QoL), ear-nose-throat examination, Mini-Mental State Examination (MMSE), orthonasal smell test (Sniffing's sticks), retronasal quick test, and taste screening were performed.

RESULTS

Cases with post-COVID-19-related smell and taste disorders deviated from non-COVID-19 post-infectious cases; the patients were younger, had a lower occurrence of anosmia/ageusia, and had higher overall smell test scores. In contrast, patients with post-COVID-19-related smell and taste disorders more frequently complained of distorted senses. Parosmia and phantosmia were more prevalent among patients with simple post-COVID-19 complaints than among complex cases and their QoL were more negatively affected.

CONCLUSION

Smell and taste function differ significantly between post-COVID-19 and other non-COVID-19 post-viral cases.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:169-174, 2023.

Taste and smell function in long-term survivors after childhood medulloblastoma/CNS-PNET

Purpose

To investigate taste and smell function in survivors, with a minimum of 2 years since treatment of childhood medulloblastoma (MB)/central nervous system supratentorial primitive neuroectodermal tumor (CNS-PNET).

Methods

This cross-sectional study included 40 survivors treated ≤ 20 years of age. Taste strips with four concentrations of sweet, sour, salt, and bitter were used to assess taste function in all participants. Score from 0 to 16; ≥ 9 normogeusia, < 9 hypogeusia, and complete ageusia which equals no sensation. No sensation of a specific taste quality equals ageusia of that quality. Thirty-two participants conducted smell testing using three subtests of Sniffin’ sticks: threshold, discrimination, and identification. Together they yield a TDI-score from 1 to 48; functional anosmia ≤ 16.00, hyposmia > 16.00– < 30.75, normosmia ≥ 30.75– < 41.50, and ≥ 41.50 hyperosmia. Results were compared with normative data. Survivors rated their taste and smell function using a numerical rating scale (NRS) score 0–10.

Results

Forty survivors with a mean time since treatment of 20.5 years, 13 (32.5%) were diagnosed with hypogeusia, nine (22.5%) of these being ageusic to one or more taste qualities. Seventeen (53%) of 32 participants were diagnosed with hyposmia. The mean scores of the olfactory subtests, and TDI score were significantly lower than normative data (P < 0.0001). The mean NRS scores of smell and taste function were 7.9 ± 1.5 and 8 ± 1.3, respectively.

Conclusion

Our study showed impaired taste and smell function in survivors of childhood MB/CNS-PNET using objective measurements. However, subjective ratings did not reflect objective findings.

Supplementary information

The online version contains supplementary material available at 10.1007/s00520-022-07048-9.

Danish Validation of a Retronasal Olfactory Powder Test and Development of a Novel Quick Retronasal Olfactory Test

Introduction  Quality of life is closely linked to retronasal olfactory function. Familiarity with odors vary, so tests need validation. Testing can be time-consuming, so a quick test and a thorough test are needed for clinical and research settings.

Objectives  The objectives of this study were to validate the original retronasal powder olfactory test in a Danish population and to develop a novel quick retronasal test for easy application.

Methods  Ninety-seven participants were included in the study, 59 healthy controls and 38 patients with olfactory impairment. The retronasal test was modified by substituting unfamiliar odors and descriptors and validated with a criterion of correct identification rate of 50% in the original test and 90% in the quick test. Items with over 90% correct identification rate in the modified original test were included in the quick test, resulting in a 10-item test.

Results  The modified retronasal olfactory test achieved good test characteristics, with a 10th percentile cut-off value of 13: sensitivity was 88.9%, specificity 83.0%, positive predictive value 78%, negative predictive value 91.7%, and the receiver operating characteristics area under the curve (ROC-AUC) was 0.86. The quick test achieved acceptable test characteristics, with a 10th percentile cut-off value of 8.2: sensitivity was 72.2%, specificity 90.6%, positive predictive value 83.9%, negative predictive value was 82.8%, and ROC-AUC 0.81.

Conclusion  Validation of both tests demonstrated satisfactory accuracy. We recommend the quick test for screening purposes, and the modified original version for a thorough evaluation. The tests are easily implemented as they are easy to understand and very affordable.

Translation and validation of the “Smell Diskettes” Olfaction Test into Arabic

Objective: This study aims to translate and validate the 'Smell Diskettes' screening tool from English into Arabic. The significance of this study stems from the lack of reliable and rapid olfaction screening tests available to Arabic speaking patients and healthcare practitioners. Methods: This is a prospective cohort, multi-center study. A forward-backward translation of the olfaction screening test was done to translate the text into Arabic. Data was collected from two groups: a control group (n=125) of which 84 percent were females (n=105) and a mean age of 22.4 of subjectively normosmic individuals from Alfaisal University and a patients group (n=82) of which 35.4 percent females (n = 29) with a mean age of 38.2, all of whom were diagnosed with olfactory disturbances related to rhinological pathologies, from King Abdulaziz University Hospital (KAUH) in Riyadh, Saudi Arabia. One of the limitations we faced due to convenience sampling and COVID-19 pandemic restrictions was the inability to perform a “test-retest” on study subjects. Results: The study included 207 subjects, out of whom 82 (40 percent) were patients from the rhinology clinic at King Abdulaziz University Hospital (KAUH) and 125 (60 percent) were recruited as controls from Alfaisal University. The average olfaction scores for the control group and the patients’ group were 7/8 and 5/8, respectively. Conclusion: This study has determined that the Arabic-language version is a valid and useful instrument used in clinical practice and for research purposes. The development of this tool will allow more patients in Arabic-speaking countries to be screened for olfactory disturbances.

Differences in Correlation between Subjective and Measured Olfactory and Gustatory Dysfunctions after Initial Ear, Nose and Throat Evaluation

Introduction  Subjective chemosensory function can differ from measured function. Previous studies on olfactory assessment have found a positive correlation between subjective and measured scores. However, information on gustatory correlation between measured and subjective functions is sparse in patients who have undergone an initial ear, nose and throat (ENT) evaluation.

Objectives  To evaluate the correlation between subjective and measured olfactory and gustatory dysfunctions in a population complaining of taste and/or smell dysfunction after an initial ENT evaluation without chemosensory testing. Furthermore, we aimed to assess the need for chemosensory testing depending on the type of subjective chemosensory dysfunction.

Methods  A case series in which subjective chemosensory function was assessed through a questionnaire and measured chemosensory function was assessed by validated clinical tests.

Results  In total, 602 patients with complaints of olfactory and/or gustatory dysfunction were included. We found that 50% of the patients with normal gustatory function and an olfactory impairment classified their olfactory impairment as a subjective taste disorder. Furthermore, 98% of the patients who rated their olfactory function as absent did have a measurable olfactory impairment, but only 64% were anosmic.

Conclusion  Subjective gustatory dysfunction was poorly correlated with measured gustatory dysfunction, and was often found to reflect olfactory dysfunction. Contrarily, subjective olfactory dysfunction was positively correlated with measurable olfactory dysfunction. Although subjective anosmia was a strong indicator of measured anosmia or hyposmia, the existence of remaining olfactory function was frequently found in these patients. Validated chemosensory testing should be performed in patients with perceived olfactory or gustatory deficits, as this could help ensure increased diagnostic precision and a relevant treatment.

Culturally modified olfactory test adapted to East-Turkey: A comparison with Sniffin' Sticks

BACKGROUND

Although the "Sniffin' Sticks" test (SST) is a widely used odor test, aplicability of odor tests is limited because of the high cost of the test and the regional-cultural differentiation of odor recognition. We aimed to evaluate our regional odor norms by applying the SST with a Modified odor test (MOT) we created for this study, and to develop a test similar to the SST, which was less expensive and probably had a higher odor definition for our region.

METHODS

This study includes 201 healthy volunteers: 91 men and 110 women over the age of 18 were included in the study. Tests were compared by applying the SST and MOT to all volunteers.

RESULTS

In all subjects, for the SST: the mean Threshold score (TS), Discrimination score (DS), and Identification score (IS) were, respectively, 10.73 ± 2.35, 11.11 ± 11.94 and 11.32 ± 2.15. TheTDI mean score was found to be 33.11 ± 5.9. In the TDI score, the 10th percentile value was found to be 26. For the MOT, the mean TS(mTS), DS(mDS), and IS(mIS) were 10.88 ± 2.31, 12 ± 2.06, and 11.95 ± 2.07, respectively, the modified test TDI(mTDI) mean was 34.68 ± 6.47. The mTDI 10th percentile value was found to be 26. In all volunteers, there was no statistically significant difference between the two tests for the mean threshold score, while the difference in the mean discrimination score, the average identification score, and the average TDI (thresold, discrimination, sum of identification scores) score was statistically significant (P < .01).

CONCLUSION

This study is the first study to compare the SST and the MOT in our region. Making low-cost modifications by adding more probable smells to the smell tests and using them in studies involving more participants will be more meaningful in evaluating normative odor scores and will result in more widespread use.

Olfactory groove meningioma with a 10-year history of smell loss and olfactory recovery after surgery

A rare cause of olfactory impairment is olfactory groove meningiomas with insidious onset of non-specific symptoms like headache, olfactory dysfunction, psychiatric symptoms such as depression, personality changes, declining cognitive function, visual disturbances or seizures. A common complication of surgery is loss of olfactory function. Still, the preservation of olfactory function should be attempted as olfactory loss often has a severe negative impact on quality of life. This report describes a woman with an olfactory groove meningioma and a 10-year history of olfactory impairment. It includes preoperatively and postoperatively extended olfactory testing, a neurosurgical approach to preserve the olfactory function and postoperative olfactory rehabilitation. After rehabilitation, the patient regained a normal olfactory function, even though the right-sided olfactory nerve could not be preserved during surgery. The case demonstrates the importance of performing neuroimaging in selected patients with olfactory loss and a method for preserving and potentially improving postoperative olfactory function.

Food preferences, food neophobia and chemosensation among adolescents with ADHD

AIM

It has been suggested that adolescents diagnosed with ADHD have an unhealthier diet compared to their peers without ADHD. The association between chemosensation (smell and taste) and dietary patterns remains unknown. The aim is to investigate unhealthy food preferences and food neophobic behaviour among adolescents diagnosed with ADHD. Additionally, it is to investigate the relationship between dietary patterns and chemosensory function.

METHODS

We enrolled 36 adolescents with and without ADHD to complete a food item and a food neophobia questionnaire and to undergo chemosensory testing.

RESULTS

Adolescents with ADHD performed significantly worse on both chemosensory tests compared to the non-ADHD group. No difference in food preferences nor food neophobia was found between the two groups.

CONCLUSION

Adolescents with ADHD have a lower score on chemosensory tests compared to their peers, suggesting impaired chemosensory function. No differences in dietary preferences nor food neophobia were seen between the two groups.

Positive association between bitter taste threshold and preference of vegetables among adolescents

AIM

Better understanding of aspects of taste in adolescents is needed since it has bearings on food policies, food industry and pharmaceutical design. Furthermore, taste preferences likely play a role in overeating and anorexia. We aimed to validate a questionnaire about taste preferences and dietary habits along with measurements of sense of smell and taste.

METHODS

We included adolescents from nearby schools in Aarhus, Denmark, from 2017 to 2019. Scoring preferences and habits on a Likert scale, they completed a food item questionnaire. Their chemosensation was tested by the Sniffin' Sticks and Taste Drop Test.

RESULTS

We included 100 adolescents: 53 males, 47 females; average age: 15.9 years (12-17 years). Retest of the questionnaire showed good reliability (Cohen's kappa: 0.5953). Snacks scored the highest average liking (4.48), whereas starches had the highest frequency of consumption (3.64). Bitter taste threshold was positively associated with liking and familiarity with vegetables (P = .032; P = .012), respectively. Healthy self-reported dietary habits were associated with a higher self-reported consumption of vegetables and a decreased consumption of snacks.

CONCLUSION

Adolescents preferred unhealthy food items, but they also reported more frequent consumption of healthy than unhealthy food items. A higher threshold for the bitter taste, that is, being less sensitive to bitter taste, was associated with higher liking and familiarity of vegetables.

Development of the Spanish Version of Sniffin's Sticks Olfactory Identification Test: Normative Data and Validity of Parallel Measures

The Sniffin' Sticks Olfactory Identification Test is a tool for measurement of olfactory performance developed in Germany and validated in several countries. This research aims to develop the Spanish version of the Sniffin' Sticks Olfactory Identification Test and obtain normative values for the Spanish population. The parameters are free recall and subjective intensity of odorants are included. The influence of possible demographic covariates such as sex, age, smoking, or educational level are analyzed, and the items that best discriminate are studied. In addition, the internal structure validity of the blue and purple versions is studied as a parallel measure, and a cultural adaptation of the purple version is carried out. For this, three independent samples of normosmic healthy volunteers were studied. To obtain normative values, the sample was of 417 participants (18-89 years). For the internal structure validity study of both versions, the sample was 226 (18-70 years), and for familiarity of the purple version, the sample was 75 participants (21-79 years). Results indicated that men and women and smokers and non-smokers perform equally. However, differences were found as age progresses, being more pronounced after 60 years old in all three measurements of the identification test. This research also provides the items that best discriminate in the blue version and a cultural adaptation for the purple version. In conclusion, the Sniffin' Sticks Odor Identification Test is a suitable tool for olfactory assessment in the Spanish population. The instrument has been expanded with two new scores, and normative data as a function of age are provided. Its parallel version also seems appropriate for testing, as items have been culturally adapted and evidence of internal structure validity for both versions is reported.

Spanish Validation for Olfactory Function Testing Using the Sniffin' Sticks Olfactory Test: Threshold, Discrimination, and Identification

The assessment of olfactory function is becoming increasingly relevant, especially in cases of cognitive decline (i.e., neurodegenerative diseases), where olfactory alterations may be relevant as potential early biomarkers. The Sniffin' Sticks Olfactory Test, developed in Germany and validated in several countries, is an objective measure of olfactory performance. This study aims to validate this test in a Spanish sample. This study included 209 healthy normosmic volunteers (154 females and 55 males) aged between 20 to 79 years (mean age = 50.11 ± 15.18 years) as the normative sample. From this group, 22 participants were retested in order to obtain test-retest reliability evidence. Odor familiarity for descriptors in the olfactory identification test was also studied on an independent healthy sample (n = 69), and required cultural modifications were applied. Results indicate that men and women, as well as smokers and non-smokers, performed equally in every test. However, significant differences were found between age groups in every score. The general trend is that olfactory function progressively decreases as a function of age, the elderly group (+60 years) being the one with the lowest scores. In conclusion, this normative data, in addition to the test's cultural modifications, allows the Sniffin' Sticks Olfactory Test to be administered on a Spanish population.

Could Early Identification of Changes in Olfactory Function Be an Indicator of Preclinical Neurodegenerative Disease? A Systematic Review

INTRODUCTION

Alzheimer's disease (AD) is a debilitating neurodegenerative disease that currently affects 850,000 individuals in the UK with estimates continuing to rise. Diagnosis is only available in the presence of significant neuronal pathology and apparent cognitive decline, meaning that treatment avenues are often limited and carry little to no effect on prognosis. Olfactory function has been shown to have a direct correlation with cognitive function and therefore may serve as a potential diagnostic tool for the detection of preclinical disease. The objective was to examine the current literature to establish the accuracy of olfactory function testing in determining current and future cognitive function.

METHODS

A systematic review was performed via Medline on 17 October 2019 using the search terms and Boolean operators 'Dementia OR Alzheimer's AND olfaction AND cognitive impairment' yielding 111 results. These were then screened using inclusion/exclusion criteria alongside a PICO strategy. After titles, abstracts and full text were screened, nine articles were included in the review and critically appraised using the AXIS and CASP tools.

RESULTS

Significant correlations are demonstrated between olfactory impairment (OI) and cognitive decline. However, there were limitations of many of the studies in that confounders such as head trauma, upper respiratory infection (URTI) and smoking history were not considered. The majority of the studies also used an olfactory screening tool that was not designed for the population being examined.

CONCLUSION

Despite improvements in olfactory testing needing to be implemented, OI is clearly impaired in neurodegenerative disease across a multitude of ages and cultures, offering an early marker of future cognitive decline. As a result of the heterogenous nature of the included studies, there is a further need for future research to ensure the sensitivity, validity and reliability of implementing olfactory testing as an early marker of future cognitive decline.

Odor Mixtures in Identification Testing Using Sniffin' Sticks: The SSomix Test

Clinical tests assessing olfactory performance have become indispensable for diagnosing olfactory dysfunction. As time and personnel resources are limited, it would be advantageous to have shorter protocols focusing on singular aspects of olfactory performance, such as odor identification. However, such a unidimensional approach is often inconclusive and needs further tests (and tools). Hence, new testing methods with high levels of sensitivity, specificity, and reproducibility are required for clinical practice. Here, we developed a Sniffin’ Sticks odor mixture identification test method (SSomix), with emphasis on resource efficiency and simplicity of administration. SSomix consists of mixtures of two and three odors applied onto a piece of paper using 11 out of 16 items from the original Sniffin’ Sticks identification test kit. A total of 66 healthy subjects and 22 patients with olfactory dysfunction were included in the study. SSomix showed good to excellent test-retest reliability and validity. The area under the receiver operating characteristics curves indicated good diagnostic accuracy in identifying patients with reduced and severely impaired olfactory function. SSomix was a suitable downsizing of the original kit, especially regarding resource efficiency.

Chemosensory Sensitivity after Coffee Consumption Is Not Static: Short-Term Effects on Gustatory and Olfactory Sensitivity

Chemosensory sensitivity has great variation between individuals. This variation complicates the chemosensory diagnostics, as well as the creation of a meal with universally high hedonic value. To ensure accurate characterization of chemosensory function, a common rule of thumb is to avoid food/beverages one hour before chemosensory testing. However, the scientific foundation of this time of fast remains unclear. Furthermore, the role of coffee on immediate chemosensitivity is not known and may have implications for optimization of gastronomy and hedonia. The aim of this study is to investigate the modularity effects of coffee consumption on immediate gustatory and olfactory sensitivity. We included 155 participants. By applying tests for olfactory and gustatory sensitivity before and after coffee intake, we found no changes in olfactory sensitivity, but significantly altered sensitivity for some basic tastants. We repeated our experimental paradigm using decaffeinated coffee and found similar results. Our results demonstrate that coffee (regular and decaffeinated) alters the subsequent perception of taste, specifically by increasing the sensitivity to sweet and decreasing the sensitivity to bitter. Our findings provide the first evidence of how coffee impacts short-term taste sensitivity and consequently the way we sense and perceive food following coffee intake-an important insight in the context of gastronomy, as well as in chemosensory testing procedures.

The Association Between Smoking on Olfactory Dysfunction in 3,900 Patients With Olfactory Loss

OBJECTIVES/HYPOTHESIS

The association between smoking and olfactory loss remains a conundrum. Prior studies have found negative and positive effects of smoking on olfactory function in the general population. However, smoking cessation seems to improve both rated and measured olfactory function. The purpose of this study was to investigate the olfactory function and smoking habits in patients with olfactory loss caused by different etiologies to unveil underlying patterns related to smoking.

STUDY DESIGN

Retrospective observational study.

METHODS

Patients were included from two specialized taste and smell centers. Patients underwent olfactory testing, clinical examination including rhinoscopy, and the underlying etiology was identified. Patterns of olfactory test scores, demographics, and etiologies were analyzed.

RESULTS

In total, 3,900 patients with olfactory loss were included. Of these, 521 were current smokers, and 316 were former smokers. Patients with a history of smoking did not have significantly lower olfactory function. Current smokers were more often affected by posttraumatic olfactory loss, but not sinonasal, postviral, or idiopathic olfactory loss.

CONCLUSIONS

Current smoking, but not former smoking, was associated with posttraumatic olfactory loss. In relation to measured olfactory function, a history of smoking was not associated to lower olfactory scores. Our findings suggest that the general recommendations of smoking cessation for patients with olfactory loss are especially relevant for patients with posttraumatic olfactory loss. The nature of this association between current smoking and posttraumatic olfactory loss has yet to be elucidated.

LEVEL OF EVIDENCE

2b Laryngoscope, 131:E8-E13, 2021.