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Delgado-Lima AH, Bouhaben J, Delgado-Losada ML. The efficacy of olfactory training in improving olfactory function: a meta-analysis. Eur Arch Otorhinolaryngol 2024; 281:5267-5284. [PMID: 38802578 PMCID: PMC11416427 DOI: 10.1007/s00405-024-08733-7] [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: 01/05/2024] [Accepted: 05/12/2024] [Indexed: 05/29/2024]
Abstract
PURPOSE Study the efficacy of olfactory training in smell recovery. METHODS An extensive search was performed through different databases in order to find articles analyzing the efficacy of olfactory training as a treatment for olfactory dysfunction. Methodological quality of primary studies within the final sample was assessed following PRISMA guidelines. Standardized mean differences in pre-post olfactory training groups, and also in experimental-control and pre-follow up if possible, were computed by Hedges' g effect size statistic. Each effect size was weighted by its inverse variance. RESULTS Final sample was composed of 36 articles (45 pre-post effect sizes). Contrasts were performed separately for odor identification, odor discrimination, odor threshold and general olfactory function. Moderate to large and heterogeneous effect was obtained for olfactory function (g = 0.755, k = 45, SE = 0.093, CI 95% = [0.572, 0.937]), different moderators had a significant effects, such as, training duration, age and anosmia diagnosis. CONCLUSION Olfactory training was found to have a positive and significant effect on rehabilitating the olfactory function.
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Affiliation(s)
- Alice Helena Delgado-Lima
- Experimental Psychology, Cognitive Processes and Speech Therapy Department, Faculty of Psychology, Complutense University of Madrid, 28223, Pozuelo de Alarcón, Spain
| | - Jaime Bouhaben
- Experimental Psychology, Cognitive Processes and Speech Therapy Department, Faculty of Psychology, Complutense University of Madrid, 28223, Pozuelo de Alarcón, Spain
| | - María Luisa Delgado-Losada
- Experimental Psychology, Cognitive Processes and Speech Therapy Department, Faculty of Psychology, Complutense University of Madrid, 28223, Pozuelo de Alarcón, Spain.
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Pieniak M, Rokosz M, Nawrocka P, Reichert A, Zyzelewicz B, Mahmut MK, Oleszkiewicz A. Null cross-modal effects of olfactory training on visual, auditory or olfactory working memory in 6- to 9-year-old children. Neuropsychol Rehabil 2024:1-22. [PMID: 38762780 DOI: 10.1080/09602011.2024.2343484] [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: 12/20/2023] [Accepted: 04/04/2024] [Indexed: 05/20/2024]
Abstract
Systematic exposure to odours (olfactory training, OT) is a method of smell loss treatment. Due to olfactory system projections to prefrontal brain areas, OT has been hypothesized to enhance cognitive functions, but its effects have been studied predominantly in adults. This study tested OT effects on working memory (WM), i.e., the ability to store and manipulate information for a short time, in healthy children aged 6-9 years. We expected OT to improve olfactory WM and establish cross-modal transfer to visual and auditory WM. Participants performed 12 weeks of bi-daily OT with either 4 odours (lemon, eucalyptus, rose, cloves; OT group) or odourless propylene glycol (placebo group). Pre- and post-training, participants' WM was measured utilizing odours (olfactory WM) or pictures (visual WM) and a word-span task (auditory WM). 84 children (40 girls) completed the study. The analyses revealed no changes in the WM performance following OT. The olfactory WM task was the most difficult for children, highlighting the need to include olfactory-related tasks in educational programmes to improve children's odour knowledge and memory, just as they learn about sounds and pictures. Further neuroimaging research is needed to fully understand the impact of OT on cognitive functions in children.
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Affiliation(s)
- Michal Pieniak
- Institute of Psychology, University of Wroclaw, Wroclaw, Poland
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Marta Rokosz
- Institute of Psychology, University of Wroclaw, Wroclaw, Poland
| | | | - Aleksandra Reichert
- Institute of Psychology, University of Wroclaw, Wroclaw, Poland
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | | | - Mehmet K Mahmut
- Food, Flavour and Fragrance Lab, School of Psychological Sciences, Macquarie University, Sydney, Australia
| | - Anna Oleszkiewicz
- Institute of Psychology, University of Wroclaw, Wroclaw, Poland
- Smell & Taste Clinic, Department of Otorhinolaryngology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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Vance DE, Del Bene VA, Kamath V, Frank JS, Billings R, Cho DY, Byun JY, Jacob A, Anderson JN, Visscher K, Triebel K, Martin KM, Li W, Puga F, Fazeli PL. Does Olfactory Training Improve Brain Function and Cognition? A Systematic Review. Neuropsychol Rev 2024; 34:155-191. [PMID: 36725781 PMCID: PMC9891899 DOI: 10.1007/s11065-022-09573-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 12/01/2022] [Indexed: 02/03/2023]
Abstract
Olfactory training (OT), or smell training,consists of repeated exposure to odorants over time with the intended neuroplastic effect of improving or remediating olfactory functioning. Declines in olfaction parallel declines in cognition in various pathological conditions and aging. Research suggests a dynamic neural connection exists between olfaction and cognition. Thus, if OT can improve olfaction, could OT also improve cognition and support brain function? To answer this question, we conducted a systematic review of the literature to determine whether there is evidence that OT translates to improved cognition or altered brain morphology and connectivity that supports cognition. Across three databases (MEDLINE, Scopus, & Embase), 18 articles were identified in this systematic review. Overall, the reviewed studies provided emerging evidence that OT is associated with improved global cognition, and in particular, verbal fluency and verbal learning/memory. OT is also associated with increases in the volume/size of olfactory-related brain regions, including the olfactory bulb and hippocampus, and altered functional connectivity. Interestingly, these positive effects were not limited to patients with smell loss (i.e., hyposmia & anosmia) but normosmic (i.e., normal ability to smell) participants benefitted as well. Implications for practice and research are provided.
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Affiliation(s)
- David E Vance
- School of Nursing, University of Alabama at Birmingham, 1701 University Boulevard, Birmingham, AL, USA.
| | - Victor A Del Bene
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Vidyulata Kamath
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Jennifer Sandson Frank
- School of Nursing, University of Alabama at Birmingham, 1701 University Boulevard, Birmingham, AL, USA
| | - Rebecca Billings
- UAB Libraries, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Do-Yeon Cho
- Department of Surgery, Veterans Affairs, University of Alabama at Birmingham, & Division of Otolaryngology, Birmingham, AL, USA
| | - Jun Y Byun
- School of Nursing, University of Alabama at Birmingham, 1701 University Boulevard, Birmingham, AL, USA
| | - Alexandra Jacob
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Joseph N Anderson
- School of Medicine, Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kristina Visscher
- Department of Neurobiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kristen Triebel
- School of Medicine, Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Karli M Martin
- School of Medicine, Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Wei Li
- Department of Clinical and Diagnostic Sciences, School of Health Professions, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Frank Puga
- School of Nursing, University of Alabama at Birmingham, 1701 University Boulevard, Birmingham, AL, USA
| | - Pariya L Fazeli
- School of Nursing, University of Alabama at Birmingham, 1701 University Boulevard, Birmingham, AL, USA
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Yan X, Benkhatar H, Chao YT, Georgiopoulos C, Hummel T. Anterior Skull Base Abnormalities in Congenital Anosmia. ORL J Otorhinolaryngol Relat Spec 2023; 86:1-12. [PMID: 37607521 DOI: 10.1159/000532077] [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: 06/08/2022] [Accepted: 07/11/2023] [Indexed: 08/24/2023]
Abstract
INTRODUCTION The structures of the skull and the brain are related to each other. Prior work in individuals with isolated congenital anosmia (ICA) showed that these individuals were characterized by olfactory bulb (OB) defects. The aim of this study was to compare the morphological pattern of the anterior skull base surrounding the OB between individuals with ICA and normosmic controls. We meant to investigate whether these features can help distinguish abnormalities from normal variation. METHODS We conducted a retrospective study to acquire T2-weighted magnetic resonance images from individuals diagnosed with ICA (n = 31) and healthy, normosmic controls matched for age and gender (n = 62). Between both groups, we compared the depth and width of the olfactory fossa, the angle of the ethmoidal fovea, as well as the angle of the lateral lamella of the cribriform plate. Within the ICA group, we further performed subgroup analyses based on the presence or absence of the OB, to investigate whether the morphology of the anterior skull base relates to the presence of OBs. The diagnostic performance of these parameters was evaluated using receiver operating characteristic analysis. RESULTS Individuals with ICA exhibited a flattened ethmoid roof and shallower olfactory fossa when compared to controls. Further, the absence of the OB was found to be associated with a higher degree of flattening of the ethmoid roof and a shallow olfactory fossa. We reached the results in the following areas under the receiver operating characteristic curves: 0.80 - angle of fovea ethmoidalis, 0.76 - depth of olfactory fossa, 0.70 - angle of lateral lamella of the cribriform plate for significant differentiation between individuals with ICA and normosmic controls. CONCLUSION Individuals with ICA exhibited an unusual anterior skull base surrounding the OB. This study supports the idea of an integrated development of OB and anterior skull base. Hence, the morphological pattern of the anterior skull base surrounding the OB helps distinguish individuals with ICA from normosmic controls and may therefore be useful for the diagnosis of ICA, although it is certainly not an invariable sign of congenital anosmia.
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Affiliation(s)
- Xiaoguang Yan
- Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
| | - Hakim Benkhatar
- Department of ENT and Head and Neck Surgery, Versailles Hospital, Le Chesnay-Rocquencourt, France
| | - Yun-Ting Chao
- Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
- Division of Rhinology, Department of Otorhinolaryngology-Head and Neck Surgery, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Charalampos Georgiopoulos
- Department of Radiology and Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Thomas Hummel
- Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
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Hu W, Chen N, Yan W, Pei P, Wei Y, Zhan X. Knowledge Mapping of Olfactory Dysfunction: A Bibliometric Study. Front Syst Neurosci 2022; 16:904982. [PMID: 35770245 PMCID: PMC9234575 DOI: 10.3389/fnsys.2022.904982] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 05/18/2022] [Indexed: 12/13/2022] Open
Abstract
Background Olfaction is one of the five basic senses of human beings. As such, olfactory dysfunction seriously affects patients' quality of life and can even endanger them. In recent years, olfactory dysfunction has attracted greater research interest, and numerous studies have been published on olfactory dysfunction. However, there are few studies on olfactory dysfunction through bibliometric analysis. This study aims to describe the current situation and identify the foci and potential new research directions of olfactory dysfunction using a bibliometric approach. Methods Articles related to olfactory dysfunction published from 2002 to 2021 were located in the Web of Science Core Collection of Clarivate Analytics (London, UK). Bibliometric analyses were conducted with the CiteSpace (Chaomei Chen, Drexel University, Philadelphia, PA, USA) and VOSviewer (Center for Science and Technology Studies, Leiden University, Leiden, Netherlands) software programs. Results The number of articles published each year showed an upward trend, especially in 2020, where a sharp increase had occurred due to the coronavirus disease 2019 (COVID-19) pandemic. The United States was the country with the most publications and the strongest international cooperation. In terms of institutions, the greatest number of publications from a single institution came from Dresden University of Technology. Thomas Hummel was the author who had contributed the most articles. An analysis of co-citation networks and burst keywords in the field revealed a shift from “gonadotropin-releasing hormone” and “apoptosis” earlier on to “olfactory training,” “COVID-19,” and “Parkinson's disease” more recently. “Outcome,” “COVID-19,” “infection,” and “pathogenesis” are topics of the research frontier and hotspots. Conclusion More attention has been paid to olfactory dysfunction as the understanding of it has improved in the past 20 years. This study provides researchers with an objective, systematic, and comprehensive analysis of the literature on olfactory dysfunction. The current frontier areas and hotspots in the field focus on the pathological mechanisms of olfactory dysfunction after infection with COVID-19 and its different prognoses. The pathophysiological mechanism of olfactory dysfunction in neurodegenerative diseases and COVID-19 will be a primary future research direction.
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Affiliation(s)
- Wen Hu
- Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Na Chen
- Department of Otolaryngology, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| | - Weiheng Yan
- Department of Otorhinolaryngology Head and Neck Surgery, Children's Hospital, Capital Institute of Pediatrics, Beijing, China
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Pei Pei
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China
| | - Yongxiang Wei
- Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
- Department of Otorhinolaryngology Head and Neck Surgery, Children's Hospital, Capital Institute of Pediatrics, Beijing, China
- *Correspondence: Yongxiang Wei
| | - Xiaojun Zhan
- Department of Otorhinolaryngology Head and Neck Surgery, Children's Hospital, Capital Institute of Pediatrics, Beijing, China
- Xiaojun Zhan
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Abstract
Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.
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Affiliation(s)
- M M Speth
- Klinik für Hals‑, Nasen‑, Ohrenkrankheiten, Hals- und Gesichtschirurgie, Kantonsspital Aarau, Aarau, Schweiz.
| | - U S Speth
- Klinik für Mund‑, Kiefer-, und Gesichtschirurgie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Deutschland
| | - A R Sedaghat
- Department of Otolaryngology - Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, USA
| | - T Hummel
- Universitäts-HNO Klinik, TU Dresden, Dresden, Deutschland
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Fokkens WJ, Landis BN, Hopkins C, Reitsma S, Sedaghat AR. Rhinology in review: from COVID-19 to biologicals. Rhinology 2021; 59:490-500. [PMID: 34812433 DOI: 10.4193/rhin21.424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We look back at the end of what soon will be seen as an historic year, from COVID-19 to real-world introduction of biologicals influencing the life of our patients. This review describes the important findings in Rhinology over the past year. A large body of evidence now demonstrates loss of sense of smell to be one of the most common symptoms of COVID-19 infection; a meta-analysis of 3563 patients found the mean prevalence of self-reported loss to be 47%. A number of studies have now shown long-term reduced loss of smell and parosmia. Given the high numbers of people affected by COVID-19, even with the best reported recovery rates, a significant number worldwide will be left with severe olfactory dysfunction. The most prevalent causes for olfactory dysfunction, besides COVID-19 and upper respiratory tract infections in general, are trauma and CRSwNP. For these CRSwNP patients a bright future seems to be starting with the development of treatment with biologics. This year the Nobel prize in Medicine 2021 was awarded jointly to David Julius and Ardem Patapoutian for their discoveries of receptors for temperature and touch which has greatly enhanced our understanding of nasal hyperreactivity and understanding of intranasal trigeminal function. Finally, a new definition of chronic rhinitis has been proposed in the last year and we have seen many papers emphasizing the importance of endotyping patients in chronic rhinitis and rhinosinusitis in order to optimise treatment effect.
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Affiliation(s)
- W J Fokkens
- Department of Otorhinolaryngology, Amsterdam University Medical Centres, location AMC, Amsterdam, The Netherlands
| | - B N Landis
- Department of Otorhinolaryngology, Geneva University Hospitals, Geneva, Switzerland; Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - C Hopkins
- Department of Otorhinolaryngology, Guy's Hospital, London, UK
| | - S Reitsma
- Department of Otorhinolaryngology, Amsterdam University Medical Centres, location AMC, Amsterdam, The Netherlands
| | - A R Sedaghat
- Department of Otolaryngology Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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