Odor Identification Research Articles

Development of parallel forms of a brief smell identification test useful for longitudinal testing.

Although there are numerous brief odor identification tests available for quantifying the ability to smell, none are available in multiple parallel forms that can be longitudinally administered without potential confounding from knowledge of prior test items. Moreover, empirical algorithms for establishing optimal test lengths have not been generally applied. In this study, we employed and compared eight machine learning algorithms to develop a set of four brief parallel smell tests employing items from the University of Pennsylvania Smell Identification Test that optimally differentiated 100 COVID-19 patients from 132 healthy controls. Among the algorithms, linear discriminant analysis (LDA) achieved the best overall performance. The minimum number of odorant test items needed to differentiate smell loss accurately was identified as eight. We validated the sensitivity of the four developed tests, whose means and variances did not differ from one another (Bradley-Blackwood test), by sequential testing an independent group of 32 subjects that included persons with smell dysfunction not due to COVID-19. These eight-item tests clearly differentiated the olfactory compromised subjects from normosmics, with areas under the ROC curve ranging from 0.79 to 0.83. Each test was correlated with the overall UPSIT scores from which they were derived. These brief smell tests can be used separately or sequentially over multiple days in a variety of contexts where longitudinal olfactory testing is needed.

Assessing how Age, Sex, Race, and Education Affect the Relationships Between Cognitive Domains and Odor Identification.

The associations between cognitive domains and odor identification are well established, but how sociodemographic variables affect these relationships is less clear. Using the survey-adapted Montreal Cognitive Assessment instrument (MoCA-SA), we assess how age, sex, race, and education shape these relationships. We first used cluster analysis and multidimensional scaling to empirically derive distinct cognitive domains from the MoCA-SA as it is unclear whether the MoCA-SA can be disaggregated into cognitive domains. We then used ordinal logistic regression to test whether these empirically derived cognitive domains were associated with odor identification and how sociodemographic variables modified these relationships. Nationally representative sample of community-dwelling US older adults. We identified 5 out of the 6 theoretical cognitive domains, with the language domain unable to be identified. Odor identification was associated with episodic memory, visuospatial ability, and executive function. Stratified analyses by sociodemographic variables reveal that the associations between some of the cognitive domains and odor identification varied by age, sex, or race, but not by education. These results suggest that (1) the MoCA-SA can be used to identify cognitive domains in survey research and (2) the performance of smell tests as a screener for cognitive decline may potentially be weaker in certain subpopulations.

PM2.5 and Dementia in a Low Exposure Setting: The Influence of Odor Identification Ability and APOE.

Growing evidence show that long term exposure to air pollution increases the risk of dementia. The aim of this study was to investigate associations between PM2.5 exposure and dementia in a low exposure area, and to investigate the role of olfaction and the APOE ɛ4 allele in these associations. Data were drawn from the Betula project, a longitudinal study on aging, memory, and dementia in Sweden. Odor identification ability was assessed using the Scandinavian Odor Identification Test (SOIT). Annual mean PM2.5 concentrations were obtained from a dispersion-model and matched at the participants' residential address. Proportional hazard regression was used to calculate hazard ratios. Of 1,846 participants, 348 developed dementia during the 21-year follow-up period. The average annual mean PM2.5 exposure at baseline was 6.77μg/m3, which is 1.77μg/m3 above the WHO definition of clean air. In a fully adjusted model (adjusted for age, sex, APOE, SOIT, cardiovascular diseases and risk factors, and education) each 1μg/m3 difference in annual mean PM2.5-concentration was associated with a hazard ratio of 1.23 for dementia (95% CI: 1.01-1.50). Analyses stratified by APOE status (ɛ4 carriers versus non-carriers), and odor identification ability (high versus low), showed associations only for ɛ4 carriers, and for low performance on odor identification ability. PM2.5 was associated with an increased risk of dementia in this low pollution setting. The associations between PM2.5 and dementia seemed stronger in APOE carriers and those with below average odor identification ability.

Identification and evaluation of fishy odorants produced by four algae separated from drinking water source during low temperature period: Insight into odor characteristics and odor contribution of fishy odor-producing algae

Disgusting fishy odor could break out inside oligotrophic drinking waterbody in winter with low temperature. Nevertheless, fishy odor-producing algae and corresponding fishy odorants were not very clear, odor contribution of fishy odorant and odor-producing algae to overall odor profile were also not well understood. In this study, the fishy odorants, produced by four algae separated from Yanlong Lake, were identified simultaneously. Odor contribution of identified odorant, separated algae to overall fishy odor profile were both evaluated. The results indicated Yanlong Lake was mainly associated with fishy odor (flavor profile analysis (FPA) intensity: 6), eight, five, five and six fishy odorants were identified and determined in Cryptomonas ovate, Dinobryon sp., Synura uvella, Ochromonas sp., respectively, which were separated and cultured from water source. Totally sixteen odorants with concentration range of 90–880 ng/L, including hexanal, heptanal, 2,4-heptadienal, 1-octen-3-one, 1-octen-3-ol, octanal, 2-octenal, 2,4-octadienal, nonanal, 2-nonenal, 2,6-nonadienal, decanal, 2-decenal, 2,4-decadienal, undecanal, 2-tetradecanone, were verified in separated algae and associated with fishy odor. Although more odorants’ odor activity value (OAV) were lower than one, approximately 89%, 91%, 87%, 90% of fishy odor intensities could be explained by reconstituting identified odorants for Cryptomonas ovate, Dinobryon sp., Synura uvella, Ochromonas sp., respectively, suggesting synergistic effect could exist among identified odorants. By calculating and evaluating total odorant production, total odorant OAV and cell odorant yield of separated algae, odor contribution rank to overall fishy odor should be Cryptomonas ovate (28.19%), Dinobryon sp. (27.05%), Synura uvella (24.27%), Ochromonas sp. (20.49%). This is the first study for identifying fishy odorants from four actually separated odor-producing algae simultaneously, this is also for the first time evaluating and explaining odor contribution of identified odorant, separated algae to overall odor profile comprehensively, this study will supply more understanding for controlling and managing fishy odor in drinking water treatment plant.

Differences in olfactory functional connectivity in early-onset depression and late-onset depression.

Late-onset depression (LOD) and early-onset depression (EOD) exhibit different pathological mechanisms and clinical phenotypes, including different extents of olfactory dysfunction. However, the brain abnormalities underlying the differences in olfactory dysfunction between EOD and LOD remain unclear. The aim of this study was to compare the functional connectivity (FC) patterns of olfactory regions between EOD patients and LOD patients and examine their relationship with cognitive function. One hundred and five patients with EOD, 101 patients with LOD and 160 normal controls (NCs) were recruited for the present study. Participants underwent clinical assessment, olfactory testing, cognitive assessments, and magnetic resonance imaging. Eight regions of the primary and secondary olfactory regions were selected to investigate olfactory FC. Patients with LOD exhibited decreased odor identification (OI) compared with patients with EOD and NCs. The LOD group exhibited decreased FC compared with the EOD and NC groups when primary and secondary olfactory regions were selected as the regions of interest (the piriform cortex, lateral entorhinal cortex, and orbital-frontal cortex). Additionally, these abnormal olfactory FCs were associated with decreased cognitive function scores and OI, and the FC between the left orbital-frontal cortex and left amygdala was a partial mediator of the relationship between global cognitive scores and OI. Overall, patients with LOD exhibited decreased FC in both the primary and secondary olfactory cortices compared with patients with EOD, and abnormal olfactory FC was associated with OI dysfunction and cognitive impairment. The FC between the orbital-frontal cortex and amygdala mediated the relationship between global cognitive function and OI.

Dupilumab for chronic rhinosinusitis with nasal polyps: real-life retrospective 12-month effectiveness data.

Dupilumab, an IL-4/13 receptor inhibitor, is approved for the treatment of uncontrolled chronic rhinosinusitis with nasal polyps (CRSwNP). We evaluated the effectiveness and safety of dupilumab for CRSwNP based on retrospective 12-month follow-up data of 41 patients. We analysed nasal endoscopy scores, patient-reported outcome measures (PROMs), 12-item SniffinSticks odor identification test (SSIT-12), total serum IgE, serum Eosinophilic Cationic Protein (ECP), and total blood eosinophil count (BEC). We performed statistical analysis using non-parametric ANOVA-type models and Spearman's correlation. At month 1, endoscopy scores, PROMs and SSIT-12 showed meaningful improvements that were maintained until month 12. Initial elevations in both median ECP and BECs returned to near baseline levels by month 12. The percentage of patients withBEC ≤ 0.6 remained increased at month 12 (42.1%) compared to baseline (19.5%). Total serum IgE levels decreased progressively and correlated with nasal polyp scores at month 12. "Adequate response" was reached in 86.8% of our cohort. Our data suggest that dupilumab is effective for the treatment of CRSwNP. The potential for short- and long-term BEC elevations in some CRSwNP patients should be carefully monitored.

Key odorant identification and odor treatment technology evaluation during the chemical synthesis process of typical pesticide

Odor pollution has become one of the important environmental problems in China. In this study, Gas Chromatography Ion Mobility Spectrometry (GC-IMS), Gas Chromatography Mass Spectrometer (GC-MS) and Flame Ionization Detector (FID) were combined to obtain comprehensive information of the odor produced during the production of Captan, a common pesticide, and to evaluate the efficiency of the odorant treatment techniques utilized by the manufacturer studied. Based on our findings, refining, an important phase during the production process of Captan, was found to be the most important factor in determining the type and the concentration of the odorant produced. Of the odorants found during the production process, perchloromethylmercaptan (CCl3SCl) and other chlorine-containing compounds are the key odorants during the production process based on the calculation of odor activity value (OAV). The current odorant treatment utilized by the manufacturer studied showed about 40 % removal rate. However, the odorant treatment produced a new odorant, dimethyl disulfide. Therefore, a much more targeted odorant treatment technique without the production of new odorants is desired and should be utilized.

Self-assessment of olfactory function using the “Sniffin’ Sticks”

BackgroundA precise and reliable test of the olfactory function is indispensable for the diagnosis of the olfactory disorder (OD). Despite of this, in a clinical context, often there is no place in daily routine for time-consuming procedures. This study aimed to examine if the assessment of olfactory function using the “Sniffin’ Sticks” is suitable for self-assessment.MethodsParticipants comprised 84 healthy control subjects (HC) and 37 OD patients. The “Sniffin’ Sticks” test battery consisting of odor threshold (T), discrimination (D) and identification (I) tests was used for self- and assisted assessments. To save time, we applied the 8-item wide step version of the T test and the 8-item D test, whereas the I task remained the same as the original version. The whole test included two sessions, with each session comprising a self-assessment part performed by the participants themselves, and an assisted-assessment part performed by the examiner.ResultsSniffin’ Sticks self-assessment was efficient in distinguishing between self-reported HC subjects and OD patients (p’s < 0.01), and the scores did not differ significantly from the assisted-assessment (p’s > 0.05). In the self-administered I and TDI tests, there was a moderate to excellent test–retest reliability (ICC = 0.51–0.93, p’s < 0.01), and a strong to excellent correlation with the assisted assessment (r = 0.71–0.92, p’s < 0.01). However, the self-administered T and D tests only exhibited low to moderate test–retest reliability (ICC = 0.30–0.72, p’s < 0.05) and correlations with the assisted test (r = 0.31–0.62, p’s < 0.05).ConclusionsThe Identification self-test is appropriate to be solely applied, and is therefore an easy-to-use alternative for olfactory screening in a larger segment of patients. The whole “Sniffin’ Sticks” self-test also shows good measurement properties and is therefore a suitable backup in clinical practice, but improvement is needed due to the simplified D and T self-test.

Increased sensitivity to unpleasant odor following acute psychological stress

Previous studies have reported increased sensitivity to malodor after acute stress in humans. However, it is unclear whether stress-related “hypersensitivity” to odors depends on odor pleasantness. Forty participants (mean age 19.13 ± 1.14 years, 21 men and 19 women) completed a stress (Trier Social Stress Test, TSST) and a control session in randomized order. Detection threshold to three odors varying in pleasantness (pleasant: β-Citronellol; neutral: 2-Heptanol; unpleasant: 4-Methylpentanoic acid), odor discrimination, odor identification, sensitivity to trigeminal odor, and suprathreshold odor perception were assessed after participants' completion of the stress or the control tasks. Salivary cortisol, subjective stress, and heart rate were assessed throughout the experiment. After TSST, participants showed an increased sensitivity for the unpleasant odor. Moreover, there were correlations between stress-related salivary cortisol and the increased sensitivity for the unpleasant odor (r = 0.32, p = 0.05) and the neutral odor (r = 0.34, p < 0.05). Besides, salivary cortisol response was correlated to the increased odor discrimination performance (Δ stress - control) (r = 0.34, p < 0.05). The post-TSST perceived stress was correlated with decreased odor identification and decreased sensitivity to the unpleasant odor. After stress, participants rated lower pleasantness for β-Citronellol than the control condition. Overall, these results suggest the impact of acute psychological stress on odor sensitivity depends on the odor valence, and that the stress-related cortisol responses may play an important role in this effect.

Olfactory training reduces pain sensitivity in children and adolescents with primary headaches.

Headache prevalence among children and adolescents has increased over the last few years. Evidence-based treatment options for pediatric headaches remain limited. Research suggests a positive influence of odors on pain and mood. We investigated the effect of repeated exposure to odors on pain perception, headache-related disability, and olfactory function in children and adolescents with primary headaches. Eighty patients with migraine or tension-type headache (mean 13.1 ± 3.29 years) participated, of whom 40 underwent daily olfactory training with individually selected pleasant odors for 3 months and 40 received state-of-the-art outpatient therapy as a control group. At baseline and after a 3-month follow-up, olfactory function [odor threshold; odor discrimination; odor identification; comprehensive Threshold, Discrimination, Identification (TDI) score], mechanical detection and pain threshold (quantitative sensory testing), electrical pain threshold, patient-reported outcomes on headache-related disability [Pediatric Migraine Disability Assessment (PedMIDAS)], pain disability [Pediatric Pain Disability Index (P-PDI)], and headache frequency were assessed. Training with odors significantly increased the electrical pain threshold compared to the control group (U = 470.000; z = -3.177; p = 0.001). Additionally, olfactory training significantly increased the olfactory function (TDI score [t(39) = -2.851; p = 0.007], in particular, olfactory threshold, compared to controls (U = 530.500; z = -2.647; p = 0.008). Headache frequency, PedMIDAS, and P-PDI decreased significantly in both groups without a group difference. Exposure to odors has a positive effect on olfactory function and pain threshold in children and adolescents with primary headaches. Increased electrical pain thresholds might reduce sensitization for pain in patients with frequent headaches. The additional favorable effect on headache disability without relevant side effects underlines the potential of olfactory training as valuable nonpharmacological therapy in pediatric headaches.

Robust odor identification in novel olfactory environments in mice

Relevant odors signaling food, mates, or predators can be masked by unpredictable mixtures of less relevant background odors. Here, we developed a mouse behavioral paradigm to test the role played by the novelty of the background odors. During the task, mice identified target odors in previously learned background odors and were challenged by catch trials with novel background odors, a task similar to visual CAPTCHA. Female wild-type (WT) mice could accurately identify known targets in novel background odors. WT mice performance was higher than linear classifiers and the nearest neighbor classifier trained using olfactory bulb glomerular activation patterns. Performance was more consistent with an odor deconvolution method. We also used our task to investigate the performance of female Cntnap2-/- mice, which show some autism-like behaviors. Cntnap2-/- mice had glomerular activation patterns similar to WT mice and matched WT mice target detection for known background odors. However, Cntnap2-/- mice performance fell almost to chance levels in the presence of novel backgrounds. Our findings suggest that mice use a robust algorithm for detecting odors in novel environments and this computation is impaired in Cntnap2-/- mice.

Relationship between the severity of olfactory dysfunction and serum zinc levels.

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. 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, 70µg/dL). The results of olfactory tests and patient backgrounds were used to compare the differences between the two groups. 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 (< 60µg/dL). In addition, significant correlations between olfactory tests (detection/recognition thresholds in the T&T olfactometer and Open Essence results) and serum zinc levels < 65µg/dL were observed. The zinc deficiency group < 70µg/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. Our findings suggest that zinc deficiency may exacerbate the severity of olfactory dysfunction. Furthermore, idiopathic olfactory dysfunction may be partly caused by zinc deficiency.

Olfactory Dysfunction in Mental Illness.

Olfactory dysfunction contributes to the psychopathology of mental illness. In this review, we describe the neurobiology of olfaction, and the most common olfactory alterations in several mental illnesses. We also highlight the role, hitherto underestimated, that the olfactory pathways play in the regulation of higher brain functions and its involvement in the pathophysiology of psychiatric disorders, as well as the effect of inflammation on neurogenesis as a possible mechanism involved in olfactory dysfunction in psychiatric conditions. The olfactory deficits present in anxiety, depression, schizophrenia or bipolar disorder consist of specific alterations of different components of the sense of smell, mainly the identification of odours, as well as the qualifications of their hedonic valence (pleasant or unpleasant). Epidemiological findings have shown that both environmental factors, such as air pollutants, and inflammatory disease of the upper respiratory tract, can contribute to an increased risk of mental illness, at least in part, due to peripheral inflammatory mechanisms of the olfactory system. In this review, we describe the neurobiology of olfaction, and the most common olfactory function alterations in several psychiatric conditions and its role as a useful symptom for the differential diagnosis. We also highlight the effect of inflammation on neurogenesis as a possible mechanism involved in olfactory dysfunction in these psychiatric conditions.

Markers of olfactory dysfunction and progression to dementia: A 12-year population-based study.

We evaluated markers of olfactory dysfunction (OD) for estimating hazard of dementia in older adults. Mild (hyposmia) and severe (anosmia) OD was classified in a population-based study of dementia-free persons (SNAC-K; n = 2473; mean age = 70 years) using the Sniffin sticks odor identification task. Combined variables were created for objective and subjective OD and for OD and APOE status. Hazard of dementia across 12 years was estimated with Cox regression. OD was associated with increased hazard of dementia (2.01; 95% confidence interval [CI] 1.60-2.52), with the strongest association for anosmia (2.92; 95% CI 2.14-3.98). Results remained consistent after adjusting for potential confounders and across age and sex subgroups. APOE ε4 carriers with anosmia had the highest hazard of dementia (ε4: 6.95; 95% CI 4.16-11.62; ε4/ε4: 19.84; 95% CI 6.17-63.78). OD is associated with increased risk of dementia, especially severe impairment in combination with genetic risk of Alzheimer's disease.

Odor deprivation influences human olfactory function

Odor deprivation leads to anatomical and neurochemical changes in the olfactory system, but its effect on human olfaction has not been systematically explored. The present randomized, controlled study aimed to investigate whether odor deprivation by different methods can affect olfactory function in humans. In the present study, sixty-one healthy participants were randomly assigned into three groups: a nasal device group (wearing an intranasal silicone air diversion system for 6–8 h daily), a mask group (wearing a filtering face piece for 6–8 h daily) and a control group (no special instructions in terms of wearing masks). Before and immediately after a 14-day study phase, all participants underwent assessments of olfactory function, nasal patency and well-being. Following the 2-week observation period, the nasal device group exhibited significantly reduced TDI scores (with especially pronounced reductions for odor threshold scores), and the mask group exhibited a minor increase in odor identification scores compared with the control group. The change in well-being scores was positively associated with changes in odor identification and TDI scores. Olfactory deprivation using an intranasal silicone air diversion device is associated with olfactory impairment (especially for odor thresholds). Highlighting the exposure-driven plasticity of the olfactory system, it may serve as a possible model of hyposmia in future studies. In addition, it may also prove useful in patients with parosmia, possibly reducing the burden of unpleasant odorous sensations.

Multielectrode recordings of cockroach antennal lobe neurons in response to temporal dynamics of odor concentrations

The initial representation of the instantaneous temporal information about food odor concentration in the primary olfactory center, the antennal lobe, was examined by simultaneously recording the activity of antagonistic ON and OFF neurons with 4-channel tetrodes. During presentation of pulse-like concentration changes, ON neurons encode the rapid concentration increase at pulse onset and the pulse duration, and OFF neurons the rapid concentration decrease at pulse offset and the duration of the pulse interval. A group of ON neurons establish a concentration-invariant representation of odor pulses. The responses of ON and OFF neurons to oscillating changes in odor concentration are determined by the rate of change in dependence on the duration of the oscillation period. By adjusting sensitivity for fluctuating concentrations, these neurons improve the representation of the rate of the changing concentration. In other ON and OFF neurons, the response to changing concentrations is invariant to large variations in the rate of change due to variations in the oscillation period, facilitating odor identification in the antennal-lobe. The independent processing of odor identity and the temporal dynamics of odor concentration may speed up processing time and improve behavioral performance associated with plume tracking, especially when the air is not moving.

Sensory processing in the auditory and olfactory domains is normal in laryngeal dystonia.

Abnormal sensory discriminatory processing has been implicated as an endophenotypic marker of isolated dystonia. However, the extent of alterations across the different sensory domains and their commonality in different forms of dystonia are unclear. Based on the previous findings of abnormal temporal but not spatial discrimination in patients with laryngeal dystonia, we investigated sensory processing in the auditory and olfactory domains as potentially additional contributors to the disorder pathophysiology. We tested auditory temporal discrimination and olfactory function, including odor identification, threshold, and discrimination, in 102 laryngeal dystonia patients and 44 healthy controls, using dichotically presented pure tones and the extended Sniffin' Sticks smell test protocol, respectively. Statistical significance was assessed using analysis of variance with non-parametric bootstrapping. Patients had a lower mean auditory temporal discrimination threshold, with abnormal values found in three patients. Hyposmia was found in 64 patients and anosmia in 2 patients. However, there were no statistically significant differences in either auditory temporal discrimination threshold or olfactory identification, threshold, and discrimination between the groups. A significant positive relationship was found between olfactory threshold and disorder severity based on the Burke-Fahn-Marsden dystonia rating scale. Our findings demonstrate that, contrary to altered visual temporal discrimination, auditory temporal discrimination and olfactory function are likely not candidate endophenotypic markers of laryngeal dystonia.

Endoscopic 1½-transseptal approach for pituitary surgery.

We previously introduced the one-and-a-half (1½) nostril endoscopic transsphenoidal approach (OETA) to reduce the damage to the nasal structures. Here, we reported the modified approach which is called the endoscopic 1½-transseptal approach (EOTA) for pituitary surgery by combining the OETA and the microscopic transseptal approach to simplify intranasal procedures and protect nasal mucosa. In EOTA, we removed the sellar lesions in a corridor that is composed of the right submucosal space and the anterior left ½ nasal cavity. We introduced EOTA with a detailed technical description and preliminary clinical outcomes. A total of 128 patients who underwent EOTA for pituitary surgery from July 2018 to September 2020 were reviewed for evaluation of the safety and efficacy of this approach. EOTA had a high gross total resection (GTR) rate and a 1ow complication rate. GTR was achieved in 106 (82.8%) patients, with 81.4% for pituitary adenomas and 93.3% for other non-adenomatous lesions. Post-operative complications included 3 patients (2.3%) with postoperative cerebrospinal fluid leak, 3 patients (2.3%) with diabetes insipidus, 5 patients (3.9%) with anterior pituitary insufficiency and 2 patients (1.6%) with meningitis. In addition, EOTA simplified the intranasal procedures, which led to shortened operation time (67.8 minutes). The results of ASK nasal-12, the Lund-Kennedy score, and the odor identification test showed that patients who underwent EOTA recovered quickly after surgery and the nasal cavity returned to the preoperative condition both apparently and physiologically one month after surgery. EOTA is a simple, safe and effective approach for pituitary lesions, which provides not only a sufficient surgical corridor for 2-surgeon/4- or 3-hands technique but also minimally invasive access to the sellar region.

Olfactory Impairment Correlates with Executive Functions Disorders and Other Specific Cognitive Dysfunctions in Parkinson's Disease.

Olfactory and cognitive disorders represent important non-motor symptoms in Parkinson's disease (PD). No clear evidence was reported about association of specific cognitive domains and olfactory impairment. The aim of this study was to evaluate the association between olfactory dysfunction and specific cognitive domains in PD patients compared to controls. 178 PD patients and 98 controls were enrolled and evaluated for odor threshold (OT), discrimination (OD), identification (OI), and TDI score using the Sniffin' Sticks test. Cognitive function was evaluated using the Montreal Cognitive Assessment scale with six sub-scores: Orientation (OIS), Attention (AIS), Language (LIS), Visuospatial (VIS), Memory (MIS), and Executive index scores (EIS). Statistically significant correlations were observed between OT versus, LIS, and between TDI score versus EIS. Multivariate linear regression analysis, including age and sex which are well-known predictors of olfactory dysfunction, showed that, among specific cognitive domains, only LIS was significant predictor for OT, VIS was a significant predictor for OD, while both EIS and AIS were significant predictors for OI, and finally only EIS was significant predictor for TDI score. Olfactory disorders in PD patients appear commonly related to dysfunction of specific cognitive domains, with strict association between global olfactory impairment and executive function deficits.

Современные направления коррекции обонятельных нарушений в клинической практике

Introduction. According to statistics, about 20% of the population have olfactory disorders of various etiologies. Among the older age group, the prevalence of the symptom is significantly higher and ranges from 40% to 65%. Olfactory disorders are most often found in diseases of the nose and paranasal sinuses of viral and infectious genesis and traumatic brain injury. There are currently no approved schemes for the correction of olfactory disorders. However, in chronic rhinosinusitis, the role of endonasal surgical interventions, systemic and topical glucocorticoids, and biological targeted therapy has been substantiated. Olfactory training in patients with olfactory dysfunction of various etiologies may be a promising treatment method. Objective. To review olfactory training techniques in general clinical practice. Materials and methods. The search for publications in the PubMed and Web of Science databases for the period from 2009 to 2023 was carried out. Results. Olfactory training is an effective method of treating olfactory dysfunction of various etiologies. The proposed olfactory training schemes involve the use of various essential oils in a standard concentration, while the duration of training can vary from 3 to 8 months. The effect of training is characterized by improved indicators of discrimination and identification of odors. At the same time, the period of restoration of the sense of smell is determined both by the degree of severity of olfactory disorders and their duration and by the age of the patient. Shorter recovery periods of olfaction were observed in patients younger than 40 years, and longer periods, in patients older than 69 years. Discussion. The study of the prospects for the use of olfactory training in the correction of olfactory dysfunction involves the study of the role of polysensory stimulation in increasing their effectiveness. The most optimal is additional stimulation of the visual analyzer by immersing the patient in a virtual scenario.