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Li Z, Richter L, Krueger T, Eichwald H, Hähner A, Hummel T. Patients with parosmia respond faster to unpleasant odors than patients with hyposmia: Insights from olfactory event-related potentials. Int Forum Allergy Rhinol 2024; 14:1446-1454. [PMID: 38584570 DOI: 10.1002/alr.23350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 03/12/2024] [Accepted: 03/22/2024] [Indexed: 04/09/2024]
Abstract
BACKGROUND Diagnosing parosmia is a challenge. The present study aimed to explore the distinctions between hyposmic patients with and without parosmia utilizing electroencephalography-derived olfactory event-related potentials (ERP). METHODS Forty-four patients with hyposmia were enrolled and divided into a group with parosmia (n = 23, mean age ± standard deviation = 48 ± 14 years, seven men) and a group without parosmia (n = 21, age = 52 ± 12 years, seven men) based on the clinical interview. Additionally, 21 healthy controls (mean age = 45 ± 14 years, six men) were included. Various measurements were obtained, including the Sniffin' Stick test, threshold tests for the odorants furfural mercaptan and 2,6-nonadienal, a modified Sniffin' Stick parosmia test, and well-being ratings. Chemosensory ERPs were recorded separately for each nostril using high-precision, computer-controlled air-dilution olfactometry. RESULTS Patients with parosmia had a decreased olfactory function similar to that observed in patients with hyposmia, although the odor sensitivity of patients with severe parosmia remained relatively unaffected. Patients with parosmia reported a decrease in well-being compared to controls. The severity of parosmia was positively correlated with odor sensitivity. Furthermore, patients with severe parosmia exhibited faster responses to unpleasant odors than patients without parosmia. CONCLUSION Overall, the present findings support the idea that parosmia predominantly occurs during olfactory recovery, significantly disturbing patients and warranting the development of effective treatments. Notably, the relatively faster responses of hyposmic patients with severe parosmia suggest that the generation of distorted olfactory responses may involve early stages of the processing of olfactory information.
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Affiliation(s)
- Zetian Li
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Luisa Richter
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Tanja Krueger
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Otorhinolaryngology, Bundeswehrkrankenhaus, Berlin, Germany
| | - Herbert Eichwald
- Department of Otorhinolaryngology, Bundeswehrkrankenhaus, Berlin, Germany
| | - Antje Hähner
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Thomas Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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Chao Y, Aden F, Göktas Ö, Schmidt F, Göktas G, Jurkov M, Georgsdorf W, Hummel T. Can immersive olfactory training serve as an alternative treatment for patients with smell dysfunction? Laryngoscope Investig Otolaryngol 2024; 9:e1270. [PMID: 38863999 PMCID: PMC11166096 DOI: 10.1002/lio2.1270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/22/2024] [Accepted: 05/08/2024] [Indexed: 06/13/2024] Open
Abstract
Objectives Olfactory training (OT) has emerged as a first-line therapeutic approach to the management of olfactory dysfunction. Conventional OT (COT) involves the systematic home-based exposure to four distinct odors. Previous research has demonstrated that immersive OT (IOT) involving full-body exposure to dozens of distinct odors could also improve overall olfactory function. This study compared IOT and COT in terms of efficacy. Methods A total of 60 patients were enrolled and assigned to three groups. The IOT group (n = 25) underwent immersive exposure to 64 odors once daily in a specialized theater. COT participants (n = 17) sniffed four typical odors in a set of four jars twice daily at home. A control group (n = 18) underwent passive observation. Olfactory function was assessed before and after training. Results Significant improvements in composite threshold-discrimination-identification (TDI) scores were observed after training in both the IOT (mean difference = 2.5 ± 1.1. p = .030) and COT (mean difference = 4.2 ± 1.3, p = .002) groups. No changes were observed in the control group. A significantly higher proportion of patients in the COT group (41%) presented improvements of clinical importance (TDI ≥5.5) compared to the controls (p = .018). The improvements attained in the IOT group (20%) were less pronounced (p = .38). Conclusion While IOT did not exhibit the same efficacy as COT in restoring olfactory function, it still demonstrated promising outcomes. Future efforts to advance olfactory recovery should focus on cross-modal integration. Level of Evidence Level 3.
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Affiliation(s)
- Yun‐Ting Chao
- Smell and Taste ClinicDepartment of Otorhinolaryngology, TU DresdenDresdenGermany
- Division of Rhinology, Department of Otorhinolaryngology‐Head and Neck SurgeryTaipei Veterans General HospitalTaipeiTaiwan
- Department of OtolaryngologyNational Yang Ming Chiao Tung UniversityTaipeiTaiwan
| | - Freya Aden
- Smell and Taste ClinicDepartment of Otorhinolaryngology, TU DresdenDresdenGermany
| | - Önder Göktas
- ENT Department, Charité Campus MitteUniversitätsmedizin BerlinBerlinGermany
| | - Friedemann Schmidt
- ENT Department, Charité Campus MitteUniversitätsmedizin BerlinBerlinGermany
| | - Gökhan Göktas
- ENT Department, Charité Campus MitteUniversitätsmedizin BerlinBerlinGermany
| | | | | | - Thomas Hummel
- Smell and Taste ClinicDepartment of Otorhinolaryngology, TU DresdenDresdenGermany
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3
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Schepens EJA, Stegeman I, Kamalski DMA. Diagnostic accuracy of the screenings Sniffin' Sticks Test (SST-12) in COVID-19 induced olfactory disorders. PLoS One 2024; 19:e0295911. [PMID: 38198490 PMCID: PMC10781020 DOI: 10.1371/journal.pone.0295911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 11/29/2023] [Indexed: 01/12/2024] Open
Abstract
Objective olfactory function can be assessed using validated olfactory tests like the Sniffin' Sticks Test (SST). However, their extensive nature makes them less suitable for clinical practice. To address this, shorter olfactory tests like the screenings Sniffin' Sticks Test (SST-12) can be used for screening purposes and reduce testing time. The SST-12 serves as a diagnostic tool for screening olfaction in cases unrelated to COVID-19. However, these screening tests are uncertain regarding their accuracy in detecting olfactory dysfunction in patients with COVID-19 as the plausible cause. We aim to determine the diagnostic accuracy of the SST-12 in adults with post-COVID-19 olfactory dysfunction. We performed a diagnostic accuracy study with data from 113 consecutive COVID-19 diagnosed patients who experienced objectified smell loss ever since. At approximately 6 months after their diagnosis, all participants underwent the SST (reference standard), part of the SST was the SST-12 (index test). Diagnostic accuracy of the SST-12 is measured as negative predictive value (NPV), positive predictive value (PPV), sensitivity, and specificity. The SST-12 detected smell loss in 85 patients among 91 patients with smell loss and ruled out smell loss in 15 patients among the 22 patients without smell loss based on the reference standard. Making sensitivity 93.4% (CI 0.87-0.97), and specificity 68.2% (CI 0.48-0.85). Out of the 92 patients with a positive test result on SST-12, 85 patients had indeed smell loss (PPV 92.4% CI 0.86-0.97), and out of the 21 patients with a negative test result, 15 patients had no smell loss regarding the reference standard (NPV 71.4% CI 0.50-0.88). The findings suggest that the SST-12 holds promise as a useful tool for identifying individuals with smell loss, also in individuals with COVID-19 as cause, but it is important to have a good understanding of the interpretation of the results of the SST-12 when considering its implementation in clinical practice.
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Affiliation(s)
- Emma J. A. Schepens
- Department of Otorhinolaryngology- Head and Neck Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
- Brain Center, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Inge Stegeman
- Department of Otorhinolaryngology- Head and Neck Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
- Brain Center, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Digna M. A. Kamalski
- Department of Otorhinolaryngology- Head and Neck Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
- Brain Center, University Medical Center Utrecht, Utrecht, The Netherlands
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Chen B, Boesen A, Olesch FT, Hummel T. A Life Without Smell: Olfactory Function in People Working in Odorless Rooms. Laryngoscope 2024; 134:382-387. [PMID: 37665094 DOI: 10.1002/lary.31015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/24/2023] [Accepted: 08/18/2023] [Indexed: 09/05/2023]
Abstract
OBJECTIVES Odorous stimulation helps to maintain or to improve olfactory function. In contrast, odor deprivation has been suggested to facilitate olfactory impairment. The aim of this study was to investigate the effects of odor deprivation in people working in an odorless environment. METHODS Fifty people working in an odorless environment for extended periods of time and 50 people not working in such environments were recruited. The participants were examined for olfactory function (using Sniffin' Sticks), nasal airflow (using peak nasal inspiratory flowmetry), self-rated olfactory function, self-rated nasal airflow, and well-being. Correlation analyses were used to explore the associations between the duration of working in odorless environment and olfaction, nasal airflow, and well-being. RESULTS The cleanroom workers exhibited slightly, but significantly reduced olfactory scores (sensitivity 7.0 ± 2.5, discrimination 11.4 ± 1.8) compared with controls (sensitivity 8.9 ± 2.5, F = 4.33, p = 0.03; discrimination 12.7 ± 1.6. F = 5.50, p = 0.001), even when controlling for age and rated nasal patency, with their self-rated olfactory function being not affected. The years of working in cleanrooms were negatively associated with olfactory function (r = 0.35, p = 0.013). No significant correlations were observed between scores of olfactory function, nasal patency, and well-being. CONCLUSION Compared with controls cleanroom workers exhibited slightly, but significantly lower olfactory scores, nasal peak flow, and well-being. Their decreased odor sensitivity was found to be associated with the number of years they had worked in the cleanroom. Overall, these results may suggest that odorous stimulation supports olfactory functioning. LEVEL OF EVIDENCE 4 Laryngoscope, 134:382-387, 2024.
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Affiliation(s)
- B Chen
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
- Geriatric Neuroscience Center, The Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou, China
| | - A Boesen
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
| | - F T Olesch
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
| | - T Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
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Dal Bò E, Natali L, Gentili C, Cecchetto C. Low odor awareness predicts reduced olfactory abilities in women with depressive symptoms, but not with anxiety symptoms. J Affect Disord 2023; 338:171-179. [PMID: 37290528 DOI: 10.1016/j.jad.2023.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 05/12/2023] [Accepted: 06/04/2023] [Indexed: 06/10/2023]
Abstract
BACKGROUND Olfactory disorders and affective symptoms are tightly related. However, the factors underlying this association are not yet understood. One candidate factor is "odor awareness": the degree of attention individuals pays to the odors. However, the association between odor awareness and olfactory abilities in individuals with affective symptoms has not been clarified yet. METHOD The present study examined whether odor awareness may moderate (a) the relation between olfactory dysfunctions and depressive and anxiety symptoms; (b) the relation between the perceptual ratings of the odors and depressive and anxiety symptoms in a sample of healthy women (n = 214). Self-report measures of depression and anxiety were collected, whereas the Sniffin' Stick test was employed to measure olfactory abilities. RESULTS Linear regression analysis revealed that individuals with higher depressive symptoms presented lower olfactory abilities and that odor awareness was a significant moderator of the association between depressive symptoms and olfactory abilities. Anxiety symptoms were not related to any of the olfactory abilities considered, and this relationship did not change according to odor awareness. The familiarity rating of the odor was significantly predicted by odor awareness. These results were confirmed by Bayesian statistics. LIMITATIONS The sample was composed only of women. CONCLUSIONS In a healthy population of women, only the presence of depressive symptoms is related to reduced olfactory performance. Odor awareness may be implicated in the development and maintenance of olfactory dysfunction; hence it could be used as a useful target for specific treatments in clinical settings.
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Affiliation(s)
- Elisa Dal Bò
- Padova Neuroscience Center (PNC), University of Padua, Via Orus 2/B, 35131 Padua, Italy; Department of General Psychology, University of Padua, Via Venezia 8, 35131 Padua, Italy.
| | - Ludovica Natali
- Department of General Psychology, University of Padua, Via Venezia 8, 35131 Padua, Italy; Centro di Ateneo Servizi Clinici Universitari Psicologici (SCUP), Via Belzoni, 84, 35121 Padua, Italy
| | - Claudio Gentili
- Padova Neuroscience Center (PNC), University of Padua, Via Orus 2/B, 35131 Padua, Italy; Department of General Psychology, University of Padua, Via Venezia 8, 35131 Padua, Italy; Centro di Ateneo Servizi Clinici Universitari Psicologici (SCUP), Via Belzoni, 84, 35121 Padua, Italy
| | - Cinzia Cecchetto
- Padova Neuroscience Center (PNC), University of Padua, Via Orus 2/B, 35131 Padua, Italy
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Pieniak M, Seidel K, Oleszkiewicz A, Gellrich J, Karpinski C, Fitze G, Schriever VA. Olfactory training effects in children after mild traumatic brain injury. Brain Inj 2023; 37:1272-1284. [PMID: 37486172 DOI: 10.1080/02699052.2023.2237889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 05/29/2023] [Accepted: 06/12/2023] [Indexed: 07/25/2023]
Abstract
OBJECTIVE Mild traumatic brain injury (mTBI) might impair the sense of smell and cognitive functioning. Repeated, systematic exposure to odors, i.e., olfactory training (OT) has been proposed for treatment of olfactory dysfunctions, including post-traumatic smell loss. Additionally, OT has been shown to mitigate cognitive deterioration in older population and enhance selected cognitive functions in adults. We aimed to investigate olfactory and cognitive effects of OT in the pediatric population after mTBI, likely to exhibit cognitive and olfactory deficits. METHODS Our study comprised 159 children after mTBI and healthy controls aged 6-16 years (M = 9.68 ± 2.78 years, 107 males), who performed 6-months-long OT with a set of 4 either high- or low-concentrated odors. Before and after OT we assessed olfactory functions, fluid intelligence, and executive functions. RESULTS OT with low-concentrated odors increased olfactory sensitivity in children after mTBI. Regardless of health status, children who underwent OT with low-concentrated odors had higher fluid intelligence scores at post-training measurement, whereas scores of children performing OT with high-concentrated odors did not change. CONCLUSION Our study suggests that OT with low-concentrated odors might accelerate rehabilitation of olfactory sensitivity in children after mTBI and support cognitive functions in the area of fluid intelligence regardless of head trauma.
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Affiliation(s)
- Michal Pieniak
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Faculty of Historical and Pedagogical Sciences, Institute of Psychology, University of Wrocław, Wroclaw, Poland
| | - Katharina Seidel
- Abteilung Neuropädiatrie, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Anna Oleszkiewicz
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Faculty of Historical and Pedagogical Sciences, Institute of Psychology, University of Wrocław, Wroclaw, Poland
| | - Janine Gellrich
- Abteilung Neuropädiatrie, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Christian Karpinski
- Klinik Und Poliklinik Für Kinderchirurgie, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Guido Fitze
- Klinik Und Poliklinik Für Kinderchirurgie, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Valentin A Schriever
- Abteilung Neuropädiatrie, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Charité - Universitätsmedizin Berlin, Berlin, Germany
- Department of Pediatric Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Mai Y, Klockow M, Haehner A, Hummel T. Self-assessment of olfactory function using the "Sniffin' Sticks". Eur Arch Otorhinolaryngol 2023; 280:3673-3685. [PMID: 36799976 PMCID: PMC10313570 DOI: 10.1007/s00405-023-07872-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/04/2023] [Indexed: 02/18/2023]
Abstract
BACKGROUND A 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. METHODS Participants 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. RESULTS Sniffin' 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). CONCLUSIONS The 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.
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Affiliation(s)
- Yiling Mai
- Department of Otorhinolaryngology, Smell and Taste Clinic, Technical University of Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
| | - Marie Klockow
- Department of Otorhinolaryngology, Smell and Taste Clinic, Technical University of Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Antje Haehner
- Department of Otorhinolaryngology, Smell and Taste Clinic, Technical University of Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Thomas Hummel
- Department of Otorhinolaryngology, Smell and Taste Clinic, Technical University of Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
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Chen B, Stein A, Olesch FT, Hummel T. Odor deprivation influences human olfactory function. Physiol Behav 2023; 262:114090. [PMID: 36681230 DOI: 10.1016/j.physbeh.2023.114090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/06/2023] [Accepted: 01/13/2023] [Indexed: 01/20/2023]
Abstract
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.
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Affiliation(s)
- Ben Chen
- Smell & Taste Clinic, Department of Otorhinolaryngology, Dresden, TU Germany; Center for Geriatric Neuroscience, The Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China.
| | - Anabel Stein
- Smell & Taste Clinic, Department of Otorhinolaryngology, Dresden, TU Germany
| | - Falk-Tony Olesch
- Smell & Taste Clinic, Department of Otorhinolaryngology, Dresden, TU Germany
| | - Thomas Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, Dresden, TU Germany
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Joshi A, Hornstein H, Thaploo D, Faria V, Warr J, Hummel T. Neural Processing of Odors with Different Well-Being Associations—Findings from Two Consecutive Neuroimaging Studies. Brain Sci 2023; 13:brainsci13040576. [PMID: 37190541 DOI: 10.3390/brainsci13040576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 03/31/2023] Open
Abstract
Much is known about the effect of odors on mood, cognition and behavior, but little is known about the relationship between odors and well-being. We investigated the neural processing of odors with different degrees of association with well-being (WB) through two large independent datasets. The study encompassed pre-testing and fMRI. During pre-testing, 100 and 80 (studies 1 and 2) young, healthy subjects participated, rating intensity, valence, and WB association for 14 (study 1) and 8 (study 2) different odors. Pre-testing resulted in the selection of two odors with high WB association (WB-associated) and two odors with lower WB association (neutral odors) for each study. Odors were delivered intranasally to the subjects who underwent fMRI scanning (44 and 41 subjects, respectively, for studies 1 and 2). We assessed brain activity for subjects when they experienced WB-associated versus neutral odors. In study 1, WB-associated odors showed increased activation in the right angular gyrus whereas in study 2, increased activity in the left angular gyrus existed, together with increased activity in the anterior cingulate cortex and posterior orbitofrontal cortex. The increased activity of higher-order cognitive and emotional regions during the processing of WB-associated odors in the two independent studies suggests a role of odors in influencing individual well-being. Moreover, the consistent activation of the angular gyrus might suggest its key role in shifting attention toward relevant emotional stimuli.
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Garamszegi SP, Banack SA, Duque LL, Metcalf JS, Stommel EW, Cox PA, Davis DA. Detection of β-N-methylamino-l-alanine in postmortem olfactory bulbs of Alzheimer's disease patients using UHPLC-MS/MS: An autopsy case-series study. Toxicol Rep 2023; 10:87-96. [PMID: 36691605 PMCID: PMC9860447 DOI: 10.1016/j.toxrep.2023.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/21/2022] [Accepted: 01/05/2023] [Indexed: 01/08/2023] Open
Abstract
Introduction Cyanobacterial blooms produce toxins that may become aerosolized, increasing health risks through inhalation exposures. Health related effects on the lower respiratory tract caused by these toxins are becoming better understood. However, nasal exposures to cyanotoxins remain understudied, especially for those with neurotoxic potential. Here, we present a case series study evaluating exposure to β-N-methylamino-l-alanine (BMAA), a cyanobacterial toxin linked to neurodegenerative disease, in postmortem olfactory tissues of individuals with varying stages of Alzheimer's disease (AD). Methods Olfactory bulb (Ob) tissues were collected during autopsies performed between 2014 and 2017 from six South Florida brain donors (ages 47-78) with residences less than 140 m from a freshwater body. A triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) method validated according to peer AOAC International guidelines was used to detect BMAA and two BMAA isomers: 2,4-diaminobutyric acid (2,4-DAB) and N-(2-aminoethyl)glycine (AEG). Quantitative PCR was performed on the contralateral Ob to evaluate the relative expression of genes related to proinflammatory cytokines (IL-6 & IL-18), apoptotic pathways (CASP1 & BCL2), and mitochondrial stress (IRF1 & PINK1). Immunohistochemistry was also performed on the adjacent olfactory tract (Ot) to evaluate co-occurring neuropathology with BMAA tissue concentration. Results BMAA was detected in the Ob of all cases at a median concentration of 30.4 ng/g (Range <LLOQ - 488.4 ng/g). Structural isomers were also detected with median concentrations of 28.8 ng/g (AEG) and 103.6 ng/g (2,4-DAB). In addition, we found that cases with BMAA tissue concentrations above the <LLOQ also displayed increased expression of IL-6 (3.3-fold), CASP1 (1.7-fold), and IRF1 (1.6-fold). Reactive microglial, astrogliosis, myelinopathy, and neuronopathy of axonal processes in the Ot were also observed in cases with higher BMAA tissue concentrations. Conclusion Our study demonstrates that the cyanobacterial toxin BMAA can be detected in the olfactory pathway, a window to the brain, and its presence may increase the occurrence of proinflammatory cytokines, reactive glia, and toxicity to axonal processes. Further studies will be needed to evaluate BMAA's toxicity via this route of exposure and factors that increase susceptibility.
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Key Words
- 2,4-DAB, 2,4-diaminobutyric acid
- AD, Alzheimer's disease
- AEG, N-(2-aminoethyl)glycine
- ALS/PDC, Amyotrophic lateral sclerosis/ parkinsonism dementia complex
- BMAA, β-N-methylamino-l-alanine
- CBs, Cyanobacterial blooms
- Cyanobacteria
- Cyanotoxin
- IL-6
- Inflammation
- OD, Olfactory dysfunction
- Ob, Olfactory bulb
- Olfactory dysfunction
- Ot, Olfactory tract
- UHPLC-MS/MS, Ultra-performance liquid chromatography and tandem mass spectrometry
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Affiliation(s)
- Susanna P. Garamszegi
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Sandra Anne Banack
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY 83001, USA
| | - Linda L. Duque
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - James S. Metcalf
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY 83001, USA
| | - Elijah W. Stommel
- Department of Neurology, Dartmouth-Hitchcock Medical Center Department of Neurology, One Medical Center Dr., Lebanon, NH 03756, USA
- Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Paul Alan Cox
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY 83001, USA
| | - David A. Davis
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Corresponding author.
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Pieniak M, Oleszkiewicz A, Avaro V, Calegari F, Hummel T. Olfactory training - Thirteen years of research reviewed. Neurosci Biobehav Rev 2022; 141:104853. [PMID: 36064146 DOI: 10.1016/j.neubiorev.2022.104853] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
Abstract
The sense of smell is interrelated with psychosocial functioning. Olfactory disorders often decrease quality of life but treatment options for people with olfactory loss are limited. Additionally, olfactory loss accompanies and precedes psychiatric and neurodegenerative diseases. Regular, systematic exposure to a set of odors, i.e., olfactory training (OT) has been offered for rehabilitation of the sense of smell in clinical practice. As signals from the olfactory bulb are directly projected to the limbic system it has been also debated whether OT might benefit psychological functioning, i.e., mitigate cognitive deterioration or improve emotional processing. In this review we synthesize key findings on OT utility in the clinical practice and highlight the molecular, cellular, and neuroanatomical changes accompanying olfactory recovery in people with smell loss as well as in experimental animal models. We discuss how OT and its modifications have been used in interventions aiming to support cognitive functions and improve well-being. We delineate main methodological challenges in research on OT and suggest areas requiring further scientific attention.
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Affiliation(s)
- Michal Pieniak
- Smell and Taste Clinic, Technische Universitat Dresden, Dresden, Germany; University of Wrocław, Faculty of Historical and Pedagogical Sciences, Institute of Psychology, Wroclaw, Poland.
| | - Anna Oleszkiewicz
- Smell and Taste Clinic, Technische Universitat Dresden, Dresden, Germany; University of Wrocław, Faculty of Historical and Pedagogical Sciences, Institute of Psychology, Wroclaw, Poland
| | - Vittoria Avaro
- CRTD-Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Federico Calegari
- CRTD-Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Thomas Hummel
- Smell and Taste Clinic, Technische Universitat Dresden, Dresden, Germany
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