A New Method for Assessment of Retronasal Olfactory Function.

OBJECTIVES/HYPOTHESIS: The aim of the study was to develop a test for the assessment of retronasal olfaction in healthy participants and patients with olfactory disorders using "tasteless" powders. STUDY DESIGN: Prospective case-control series. METHODS: A total of 150 participants (110 women, 40 men, mean age = 40 ± 16 years) were recruited for this study; 100 were healthy controls and 50 were patients with olfactory loss due to infections of the upper respiratory tract (n = 25), idiopathic causes (n = 12), sinonasal disease (n = 7), and head trauma (n = 6). Orthonasal olfactory function was evaluated using the Sniffin' Sticks test battery, and retronasal olfaction was evaluated using powders lacking distinctive tastes administered to the oral cavity. To establish test-retest reliability, healthy participants had their orthonasal and retronasal function tested twice. RESULTS: The validity analyses revealed that the selected 16 stimuli differentiated between normosmic participants and patients with olfactory loss, and that retronasal and orthonasal olfaction were highly correlated. CONCLUSIONS: The results of the present study indicate that patients with olfactory loss and controls can be clearly separated using a reliable test of retronasal olfaction based on 16 retronasal stimuli. LEVEL OF EVIDENCE: 2b Laryngoscope, 131:E324-E330, 2021.

Smell and taste loss in COVID-19 patients: assessment outcomes in a Victorian population.

Background: It has been noted that olfactory and gustatory disturbances may precede or accompany the typical features of COVID-19, such as fever and cough. Hence, a high index of suspicion is required when patients report sudden loss of smell or taste, in order to facilitate timely diagnosis and isolation.Aims/objectives: The aim of this study was to assess the frequency of olfactory and gustatory disturbances in COVID-19 positive patients from a cohort representative of Melbourne, Australia.Methods: A retrospective descriptive study was conducted on patients who tested positive for COVID-19. Standardised phone consultations and online follow-up questionnaires were performed to assess clinical features of COVID-19, with a focus on smell and taste disorders.Results: The most frequent symptoms experienced were taste and smell disturbances with 74% experiencing either smell or taste disturbance or both. Post-recovery, 34% of patients continued to experience ongoing hyposmia and 2% anosmia, whereas 28% continued to suffer from hypogeusia or ageusia.Conclusion and significance: This study presents the high rates of improvement of both olfactory and gustatory disturbance in a short-lived period. It also highlights the importance of these symptoms in prompting appropriate testing, quarantine precautions, initiate early olfactory retraining and the potential for continued sensory disturbance.

Ethyl alcohol threshold test: a fast, reliable and affordable olfactory Assessment tool for COVID-19 patients.

OBJECTIVE: COVID-19 patients may present mild symptoms. The identification of paucisymptomatic patients is paramount in order to interrupt the transmission chain of the virus. Olfactory loss could be one of those early symptoms which might help in the diagnosis of COVID-19 patients. In this study, we aim to develop and validate a fast, inexpensive, reliable and easy-to-perform olfactory test for the screening of suspected COVID-19 patients. STUDY DESIGN: Phase I was a case-control study and Phase II a transversal descriptive study. SUBJECTS AND METHODS: Olfaction was assessed with the ethyl alcohol threshold test and symptoms with visual analogue scales. The study was designed in two phases: In Phase I, we compared confirmed COVID-19 patients and healthy controls. In Phase II, patients with suspected COVID-19 infection referred for testing were studied. RESULTS: 275 participants were included in Phase I, 135 in Phase II. The ROC curve showed an AUC of 0.749 in Phase I, 0.737 in Phase II. The cutoff value which offered the highest amount of correctly classified patients was ≥ 2 (10% alcohol) for all age intervals. The odds ratio was 8.19 in Phase I, 6.56 in Phase II with a 75% sensitivity. When cases report normal sense of smell (VAS < 4), it misdiagnoses 57.89% of patients detected by the alcohol threshold test. CONCLUSION: The olfactory loss assessed with the alcohol threshold test has shown high sensitivity and odds ratio in both patients with confirmed COVID-19 illness and participants with suspected SARS-CoV-2 infection.

Is anosmia the price to pay in an immune-induced scorched-earth policy against COVID-19?

Since the outbreak of Coronavirus Disease 2019 (COVID-19), loss of smell has increasingly been reported as a frequent clinical sign. Understanding the underlying mechanism and the prognostic value of this symptom will help better manage patients. SARS-CoV-2, as SARS-CoV-1, may likely spread to the central nervous system (CNS) via the olfactory nerve, a known gateway for respiratory neurotropic viruses. We hypothesise that sudden loss of smell due to COVID-19 is the consequence of a protective host defence mechanism involving apoptosis of olfactory receptor neurons. Sacrificing smelling over neuroprotection is a logical strategy, even more so as olfaction is the only sense with the ability to regenerate in adults. Induced apoptosis of olfactory neurons has been shown in mice, successfully preventing neuroinvasion. On the other hand, adult olfactory neurogenesis has been shown to be regulated in part by the immune system, allowing to restore olfactory function. Understanding anosmia as part of a defence mechanism would support the concept of sudden anosmia as being a positive prognostic factor in the short term. Also, it may orient research to investigate the risk of future neurodegenerative disease linked to persisting coronavirus in neurons.

Discussion on Standardization of Forensic Assessment of Olfactory Dysfunction.

ABSTRACT: With the development of society, the improvement of living standards and the advancement of research methods, olfactory function has been paid more and more attention. Therefore, higher requirements for the forensic identification of olfactory function have also been put forward. Standardization construction of forensic medical examination and identification of olfactory dysfunction is urgently needed. Based on a comprehensive review of olfactory function and forensic assessment of olfactory dysfunction, this paper elaborates on problems related to the principles and timing of forensic assessment of olfactory dysfunction, the requirements of identification of traumatic olfactory dysfunction, the subjective and objective methods of examination of olfactory function. Strict control of the above issues is an important mean of standardization of forensic assessment of olfactory dysfunction.

Clinical Usefulness of Self-Rated Olfactory Performance-A Data Science-Based Assessment of 6000 Patients.

In clinical practice, with its time constraints, a frequent conclusion is that asking about the ability to smell may suffice to detect olfactory problems. To address this question systematically, 6049 subjects were asked about how well they can perceive odors, with 5 possible responses. Participants presented at a University Department of Otorhinolaryngology, where olfactory testing was part of the routine investigation performed in patients receiving surgery at the clinic (for various reasons). According to an odor identification test, 1227 subjects had functional anosmia and 3113 were labeled with normosmia. Measures of laboratory test performance were used to assess the success of self-estimates to capture the olfactory diagnosis. Ratings of the olfactory function as absent or impaired provided the diagnosis of anosmia at a balanced accuracy of 79%, whereas ratings of good or excellent indicated normosmia at a balanced accuracy of 64.6%. The number of incorrect judgments of anosmia increased with age, whereas false negative self-estimates of normosmia became rarer with increasing age. The subject's sex was irrelevant in this context. Thus, when asking the question "How well can you smell odors?" and querying standardized responses, fairly accurate information can be obtained about whether or not the subject can smell. However, this has to be completed with the almost 30% (355 subjects) of anosmic patients who judged their ability to smell as at least "average." Thus, olfactory testing using reliable and validated tests appears indispensable.

Assessment of the Olfactory Function in Patients With Idiopathic Intracranial Hypertension Using the Sniffin' Sticks Test: A Case-Control Study.

OBJECTIVE: Despite the lack of recognition in clinical practice, there is increasing evidence that patients with idiopathic intracranial hypertension may suffer from hyposmia. The current case-control study aims to evaluate olfactory dysfunction in a large series of patients with idiopathic intracranial hypertension. METHODS: All subjects, 44 idiopathic intracranial hypertension patients and 57 healthy controls, underwent olfactory function assessment using standardized "Sniffin' Sticks" test at a tertiary referral center of a university hospital. Threshold, discrimination, identification, and total threshold-discrimination-identification scores have been determined and analyzed statistically. RESULTS: Idiopathic intracranial hypertension patients had significantly lower threshold (6.5 [3.69] vs 8 [1.88], P < .001, 95% CI [-2.250, -0.750]) and threshold-discrimination-identification scores (29.75 [5.56] vs 32.5 [5.25], P = .003, 95% CI [-4.250, -0.750]). Twenty-five patients (57%) were diagnosed with hyposmia. Test scores of patients with active idiopathic intracranial hypertension (n = 18) were not statistically different from patients with inactive disease (n = 26), except for discrimination score (14 [2.50] vs 11 [2.25], P = .005, 95% CI [-3.000, -1.000]). Although idiopathic intracranial hypertension patients with a cerebrospinal fluid opening pressure of ≥330 mmH2 O had lower test scores, the difference was significant only for total threshold-discrimination-identification scores (28.5 [5.50] vs 30.5 [4.38], P = .044, 95% CI [0.750, 5.500]). Multiple regression analysis revealed that test scores were related to disease activity, cerebrospinal fluid opening pressure, papilledema, headache, and medication. CONCLUSION: Our clinical study revealed significant olfactory dysfunction in patients with idiopathic intracranial hypertension compared with healthy controls. Future research should employ larger samples to search for usability of olfactory testing in clinical management of patients with idiopathic intracranial hypertension.

Contributions of olfactory and neuropsychological assessment to the diagnosis of first-episode schizophrenia.

OBJECTIVE: First-episode schizophrenia and schizoaffective patients (SZ+) show olfactory impairments, but how these relate to cognitive dysfunction remains unclear. We examined the relationship between cognitive and olfactory dysfunction in SZ+ and the clinical utility of these measures in the assessment of SZ+ patients. METHOD: First-episode SZ+ patients (n = 63) and controls (n = 63) were administered tests of odor identification and discrimination in addition to measures of manual dexterity, processing speed, attention and working memory, executive functioning, ideational fluency, and memory. We analyzed the relationships between olfactory and cognitive variables and conducted stepwise multiple regressions to identify which cognitive indices best predicted olfactory performance within the SZ+ group. Linear discriminant analysis was used to identify which measures best distinguished cases from controls. RESULTS: Among patients, odor discrimination correlated with perseverative errors and odor identification correlated with bilateral manual dexterity. Odor discrimination performance was best predicted by perseverative errors and letter fluency, whereas odor identification ability was best predicted by manual dexterity. Stepwise linear discriminant analysis revealed that manual dexterity, letter-guided word fluency, and odor discrimination best distinguished SZ+ from healthy adults. CONCLUSIONS: These findings indicate that manual dexterity, letter-guided word fluency, and odor discrimination may provide incremental information that strengthens a diagnosis of SZ+. Although odor discrimination tasks have received limited attention in schizophrenia studies, the extant data along with the present results indicate that odor discrimination tasks may have utility over odor identification measures as a neurodevelopmental risk marker. Additional studies examining odor discrimination as a predictor of SZ spectrum illness are warranted. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Comparative Motor Pre-clinical Assessment in Parkinson's Disease Using Supervised Machine Learning Approaches.

Millions of people worldwide are affected by Parkinson's disease (PD), which significantly worsens their quality of life. Currently, the diagnosis is based on assessment of motor symptoms, but interest toward non-motor symptoms is increasing, as well. Among them, idiopathic hyposmia (IH) is associated with an increased risk of developing PD in healthy adults. In this work, a wearable inertial device, named SensFoot V2, was used to acquire motor data from 30 healthy subjects, 30 people with IH, and 30 PD patients while performing tasks from the MDS-UPDRS III for lower limb assessment. The most significant and non-correlated extracted parameters were selected in a feature array that can identify differences between the three groups of people. A comparative classification analysis was performed by applying three supervised machine learning algorithms. The system resulted able to distinguish between healthy and patients (specificity and recall equal to 0.967), and the people with IH can be identified as a separate class within a three-group classification (accuracy equal to 0.78). Thus, the system could support the clinician in objective assessment of PD. Further, identification of IH together with changes in motor parameters could be a non-invasive two-step approach to investigate the early onset of PD.

[Assessment of olfactory and gustatory function with validated tests]. / Beurteilung der chemosensorischen Funktion mit validierten Riech- und Schmecktests.

Approximately 5 % of the general population is affected by functional anosmia. An additional 15 % exhibit decreased olfactory function. Many of these individuals ask ENT-doctors or neurologists for help. A cornerstone of the counselling process is the assessment of olfactory function. The aim of this work is to give a differentiated overview about the administration of commonly used psychophysical tests for olfactory and gustatory function including their normative data. The use of standardized, reliable and validated tools is mandatory to provide patients with state-of the-art counseling on treatment options.

Severe hyposmia and aberrant functional connectivity in cognitively normal Parkinson's disease.

OBJECTIVE: Severe hyposmia is a risk factor of dementia in Parkinson's disease (PD), while the underlying functional connectivity (FC) and brain volume alterations in PD patients with severe hyposmia (PD-SH) are unclear. METHODS: We examined voxel-based morphometric and resting state functional magnetic resonance imaging findings in 15 cognitively normal PD-SH, 15 cognitively normal patients with PD with no/mild hyposmia (PD-N/MH), and 15 healthy controls (HCs). RESULTS: Decreased gray matter volume (GMV) was observed in the bilateral cuneus, right associative visual area, precuneus, and some areas in anterior temporal lobes in PD-SH group compared to HCs. Both the PD-SH and PD-N/MH groups showed increased GMV in the bilateral posterior insula and its surrounding regions. A widespread significant decrease in amygdala FC beyond the decreased GMV areas and olfactory cortices were found in the PD-SH group compared with the HCs. Above all, decreased amygdala FC with the inferior parietal lobule, lingual gyrus, and fusiform gyrus was significantly correlated with both reduction of Addenbrooke's Cognitive Examination-Revised scores and severity of hyposmia in all participants. Canonical resting state networks exhibited decreased FC in the precuneus and left executive control networks but increased FC in the primary and high visual networks of patients with PD compared with HCs. Canonical network FC to other brain regions was enhanced in the executive control, salience, primary visual, and visuospatial networks of the PD-SH. CONCLUSION: PD-SH showed extensive decreased amygdala FC. Particularly, decreased FC between the amygdala and inferior parietal lobule, lingual gyrus, and fusiform gyrus were associated with the severity of hyposmia and cognitive performance. In contrast, relatively preserved canonical networks in combination with increased FC to brain regions outside of canonical networks may be related to compensatory mechanisms, and preservation of brain function.

Periodic olfactory assessment in patients undergoing skull base surgery with preservation of the olfactory strip.

OBJECTIVES/HYPOTHESIS: Others have reported olfactory disturbances following endoscopic approaches to the skull base. However, there is a lack of consensus on the extent and duration of dysfunction. This study aimed to compare our results with previously published work and to validate the olfactory strip-sparing approach. STUDY DESIGN: Prospective study to assess olfaction in 50 patients scheduled to undergo resection of skull base tumors via extended endoscopic approaches. METHODS: Patients were divided into two groups. Group I had a nasoseptal flap (NSF), and group II included patients in whom rescue flaps were performed bilaterally. Olfactory outcomes were assessed using repeated University of Pennsylvania Smell Identification Test at baseline, 6 weeks, 3 months, and 6 months following surgery. RESULTS: Ultimately, 42 patients (seven group I and 35 group II) were available for assessment. Scores for group I were lower than at baseline at 6 weeks postoperatively (30.71 ± 5.5 vs. 24.5 ± 5.4; P = .05). However, by the third postoperative month the scores had improved to a level that was not significantly different from baseline (29.0 ± 3.7; P = .5). At 6 months, the score was 30.0 ± 3.9. Patients in group II showed no difference between their baseline and 6-week scores (31.5 ± 5.3 vs. 29.7 ± 5.9; P = .16). Six months postoperatively, the score was significantly higher (33.78 ± 3.6; P = .04). CONCLUSIONS: Expanded endoscopic approaches to skull base tumors involving reconstruction with an NSF are associated with a short-term negative impact on olfaction. Olfaction does not seem to be affected by the surgical resection of pituitary adenomas associated with rescue flaps. Identification of the olfactory epithelium and meticulous harvesting of the NSF are critical to preserve olfaction. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1970-1975, 2017.

Sinonasal symptom assessment by the self-reported DyNaChron questionnaire: Before or after consultation?

OBJECTIVE: Assessment of sinonasal symptoms on a self-reported questionnaire is thoroughly subjective, but indispensable for quantifying symptoms. The present study sought to compare responses on the DyNaChron questionnaire just before and just after consultation for chronic sinonasal dysfunction. MATERIALS AND METHODS: 78 patients (mean age, 43.1±16.9 years) consulting for chronic sinonasal dysfunction took part in a prospective study, responding to the computerized version of the DyNaChron self-reported questionnaire, in a dedicated room, just before and just after medical interview and physical examination. RESULTS: Most patients tended to grade symptoms as less severe after consultation. Significant differences in mean score were found for nasal obstruction (difference of 0.94/10), anterior (0.40) and posterior rhinorrhea (0.26), olfactory disorder (0.65), and facial pain and headache (0.65), but not for chronic cough. CONCLUSION: Self-reported scores for chronic sinonasal dysfunction differ slightly from before to after consultation. They are therefore to be interpreted with caution, taking account of possible factors of bias.

Normal 'heart' in Parkinson's disease: is this a distinct clinical phenotype?

BACKGROUND AND PURPOSE: Reduction of metaiodobenzylguanidine (MIBG) uptake has been observed in almost all patients with Parkinson's disease (PD), associated with hyposmia, orthostatic hypotension and rapid eye movement sleep behavioral disorder (RBD). In contrast, a subgroup of patients with PD with normal MIBG uptake have been reported to have milder disease and preserved cognition compared with those with lower MIBG. The aim of this study was to investigate whether non-motor manifestations of PD differ between patients with normal and abnormal myocardial MIBG uptake. METHODS: Among 160 de-novo cases of PD, 44 had normal MIBG uptake. Twelve candidate non-motor features were evaluated using questionnaires and laboratory tests. RESULTS: Patients with decreased MIBG uptake had more constipation, RBD, cognitive impairment, hyposmia and orthostatic hypotension than did those with normal MIBG uptake. On linear regression analysis, orthostatic hypotension, olfactory function and probable RBD were significantly associated with MIBG uptake in PD. The principal component analysis showed that the group with normal MIBG was not associated with non-motor impairments. CONCLUSIONS: These results suggest that patients with PD with normal MIBG scans have a relatively low disease burden compared with those with abnormal MIBG. Fewer synuclein pathologies in the myocardia and sympathetic ganglia in PD with preserved MIBG uptake might be associated with lower threshold patterns of Braak synuclein pathology for non-motor manifestations compared with PD with decreased MIBG.

Assessment of Olfactory Function in MAPT-Associated Neurodegenerative Disease Reveals Odor-Identification Irreproducibility as a Non-Disease-Specific, General Characteristic of Olfactory Dysfunction.

Olfactory dysfunction is associated with normal aging, multiple neurodegenerative disorders, including Parkinson's disease, Lewy body disease and Alzheimer's disease, and other diseases such as diabetes, sleep apnea and the autoimmune disease myasthenia gravis. The wide spectrum of neurodegenerative disorders associated with olfactory dysfunction suggests different, potentially overlapping, underlying pathophysiologies. Studying olfactory dysfunction in presymptomatic carriers of mutations known to cause familial parkinsonism provides unique opportunities to understand the role of genetic factors, delineate the salient characteristics of the onset of olfactory dysfunction, and understand when it starts relative to motor and cognitive symptoms. We evaluated olfactory dysfunction in 28 carriers of two MAPT mutations (p.N279K, p.P301L), which cause frontotemporal dementia with parkinsonism, using the University of Pennsylvania Smell Identification Test. Olfactory dysfunction in carriers does not appear to be allele specific, but is strongly age-dependent and precedes symptomatic onset. Severe olfactory dysfunction, however, is not a fully penetrant trait at the time of symptom onset. Principal component analysis revealed that olfactory dysfunction is not odor-class specific, even though individual odor responses cluster kindred members according to genetic and disease status. Strikingly, carriers with incipient olfactory dysfunction show poor inter-test consistency among the sets of odors identified incorrectly in successive replicate tests, even before severe olfactory dysfunction appears. Furthermore, when 78 individuals without neurodegenerative disease and 14 individuals with sporadic Parkinson's disease were evaluated twice at a one-year interval using the Brief Smell Identification Test, the majority also showed inconsistency in the sets of odors they identified incorrectly, independent of age and cognitive status. While these findings may reflect the limitations of these tests used and the sample sizes, olfactory dysfunction appears to be associated with the inability to identify odors reliably and consistently, not with the loss of an ability to identify specific odors. Irreproducibility in odor identification appears to be a non-disease-specific, general feature of olfactory dysfunction that is accelerated or accentuated in neurodegenerative disease. It may reflect a fundamental organizational principle of the olfactory system, which is more "error-prone" than other sensory systems.

Assessment of Chemosensory Function Using "Sniffin' Sticks", Taste Strips, Taste Sprays, and Retronasal Olfactory Tests.

BACKGROUND: Approximately 5% of the general population is affected by functional anosmia. An additional 15% exhibit decreased olfactory function. Many of these individuals ask ENT-doctors or neurologists for help. A cornerstone of the counselling process is the assessment of olfactory function. The aim of this work is to give a differentiated overview about the administration of commonly used psychophysical tests for olfactory and gustatory function including their normative data. CONCLUSION: The use of standardized, reliable and validated tools is mandatory to provide patients with state-of the-art counseling on treatment options.

Olfaction in People with Down Syndrome: A Comprehensive Assessment across Four Decades of Age.

BACKGROUND: Down syndrome (DS) shows neuropathology similar to Alzheimer disease, which presents olfactory impairment. Previous work showed olfactory impairment in DS, but a comprehensive evaluation of olfactory function in DS is lacking. METHODS: We investigated a large number (n = 56; M = 31, F = 25) DS participants (age range18-57y) using the "Sniffin' Sticks" Extended test. This comprises three subtests (threshold, discrimination, and identification) yielding a global score (TDI) defining normosmia, hyposmia, and functional anosmia. To the best of our knowledge, this is the second largest group of DS people investigated for olfactory function ever. Age- and sex matched euploid individuals (n = 53) were the control. RESULTS: In DS, TDI was lower (16.7±5.13 vs. 35.4±3.74; P<0.001), with DS people performing worse in any subtests (P<0.001 for all); 27 DS participants showed functional anosmia (i.e., TDI<16). In DS, age was weakly and negatively correlated with TDI (r = -0.28, P = 0.036) and identification (r = -0.34, P = 0.012). When participants were stratified in young adults (18-29y) and older adults (30-61y), a significant effect of age was found for identification in both DS (young adults, 8.3±2.58; older adults, 6.9±2.99; P = 0.031) and control (young-adult, 14.3±1.18, older adult, 13.0±1.54; P = 0.016). CONCLUSION: Olfactory function is overall severely impaired in DS people and may be globally impaired at relatively young age, despite of reportedly normal smell. However, specificity of this olfactory profile to DS should be considered with some caution because cognition was not evaluated in all DS participants and comparison with a control group of non-DS individuals having cognitive disabilities was lacking. Further study is required to longitudinally assess olfactory dysfunction in DS and to correlate it with brain pathology.

Electroencephalographic Response to Different Odors in Healthy Individuals: A Promising Tool for Objective Assessment of Olfactory Disorders.

The aim of the present study was to examine human central nervous system response to three different odors. Electrophysiological activity was recorded in the baseline state and for 3 odors, lemon, peppermint, and vanilla, in 16 healthy participants. Electrodes were separated into groups according to the spatial position on the head. Fast Fourier transformation was performed on every set, and mean value of activity in theta was exported. As theta showed statistically significant results, further analysis was based only on the theta frequency band. On electrodes FP1, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, TP9, CP5, CP1, CP2, CP6, P7, P3, Pz, P4, P8, PO9, and PO10 there was statistically significant difference in the electrical activity of the brain between four conditions. For peppermint and lemon, there was statistically significant difference in activity between different regions-F(1.576, 23.637)=16.030, P=.000 and F(1.362, 20.425)=4.54, P=.035, respectively-where the activity in the central area was significantly reduced compared with the activity in the other 4 areas and in the left and right anterior and left posterior area, respectively. There was no statistically significant difference for vanilla between specific areas, F(1.217, 18.257)=1.155, P=.309. The results indicate that olfactory stimuli can affect the frequency characteristics of the electrical activity of the brain.

A world without the olfactory dimension.

This article aims to describe what is it like to perceive reality when suffering from congenital anosmia. Nevertheless, this objective entails a fundamental difficulty. Since I have never had the experience of olfaction, it seems natural to me to live in a world lacking the olfactory dimension; this subjective perception is the only one I know and in consequence it is difficult to describe. For this reason, in recent years I have begun to develop long conversations with other people suffering from congenital anosmia, people who have lost their sense of olfaction in adulthood and also people with a good sense of smell. My goal is to draw a map showing the principal differences that might allow us to develop a systematic comparison. Obviously, this is not an experimental or quantitative scientific procedure, but only a modest attempt to compare personal stories about subjective experiences. It is a philosophical-literary exercise, and does not aim to be anything other than that. But I hope it will help to formulate meaningful questions, which would then need a properly scientific approach. In the first part of this article I want to try to describe how I became aware that other people could smell; and in a second part, I will try to examine the consequences of anosmia in different areas of everyday life: nourishment, relationships with people, own body perception, natural or urban environments perception, time perception, and finally aesthetic appreciation and the implications of living in a world without stench.