Impact of post-COVID-19 olfactory disorders on quality of life, hedonic experiences and psychiatric dimensions in general population.

BACKGROUND AND OBJECTIVE: Olfactory disorders in COVID-19 impact quality of life and may lead to psychological impairments. Prevalence ranges from 8 to 85%, persisting in about 30% of cases. This study aimed to evaluate the 6-month post-COVID-19 impact on quality of life, hedonic experiences, anxiety and depression due to olfactory disorders. Additionally, it sought to compare psychophysical tests and self-perceived olfactory evaluations. METHODS: A prospective, longitudinal study was conducted over baseline (T0) and 6 months (T1) on individuals with persistent olfactory disorders post-COVID-19 for more than 6 weeks. Psychophysical tests employed the Sniffin' Sticks Test® (TDI score), and self-perceived olfactory evaluation used a Visual Analogue Scale. Quality of life was assessed with an Olfactive Disorder Questionnaire and the French version of the Quality of Life and Diet Questionnaire. Hedonic experiences were gauged using the Snaith-Hamilton Pleasure Scale, while anxiety and depression dimensions were measured by The State-Trait Anxiety Inventory, The Post Traumatic Stress Checklist Scale, and Hamilton Rating Scale for Depression. Participants were classified into the "normosmic group" (NG) and the "olfactory disorders group" (ODG) at T0 and T1 based on the TDI score. RESULTS: Were included 56 participants (58.93% women, 41.07% men) with a mean age of 39.04 years and a mean duration of post-COVID-19 olfactory disorders of 5.32 months. At T1, ODG had a significantly lower quality of life and hedonic experiences than NG. No significant differences in anxiety and depression dimensions were observed between groups. At T0, psychophysical tests and self-perceived olfactory evaluations were significantly correlated with quality of life and hedonic experiences in both groups. At T1, self-perceived olfactory evaluation in NG correlated significantly with quality of life, hedonic experiences, anxiety and depression dimensions, whereas ODG only correlated with hedonic experiences. CONCLUSION: Individuals with persistent post-COVID-19 olfactory disorders after six months demonstrated compromised quality of life and hedonic experiences. Self-perceived olfactory evaluation played a more significant role in influencing quality of life and the dimension of anxiety and depression than the psychophysical presence of olfactory disorders. These findings emphasize the importance of considering patients' perceptions to comprehensively assess the impact of olfactory disorders on their well-being. TRIAL REGISTRATION: ClinicalTrials.gov number (ID: NCT04799977).

Effectiveness and rapidity on olfatory fuction recovery in CRS patients treated with Dupilumab: a real life prospective controlled study.

BACKGROUND: Recovery of olfactory function plays a prominent role in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). While rates and timing of such recovery vary, monoclonal antibodies might yield better results which we aimed at evaluating with this study. METHODOLOGY: A prospective controlled study was conducted at our tertiary otolaryngological center from April 1, 2021, to October 1, 2022, in CRSwNP patients. We included an active group (n = 60 patients) performing dupilumab treatment and a control group (n = 60 patients) treated with intranasal and oral corticosteroids. Primary endpoints were changes in smell visual analogical scale (VAS) and SS-I (Sniffin' Sticks-identification) scores, and olfactory recovery rate. The secondary efficacy endpoints were nasal obstruction, rhinorrhea, headache, SNOT-22, and nasal congestion score (NCS). RESULTS: At 6 months, the active group demonstrated better outcomes than control in SS-I scores (10.23 ± 4.21 vs.3.68 ± 3.08; p < 0.001). No significant differences were found in blood eosinophil count, SNOT-22, and NPS (p > 0.05 for all). Olfactory function in the treatment arm improved in 86.66% (52/60 cases), with normal scores in 48.33% (29/60), while the control group reported a lower recovery rate (3/60; 5%), with no normal olfaction cases. Log-rank comparison for Kaplan-Meier functions was statistically significant (p < 0.001), but no differences were found in subanalysis in the active group based on blood eosinophil count at baseline, SNOT-22, and NPS scores. CONCLUSIONS: Patients who receive dupilumab treatment may experience a faster recovery of olfactory function compared to those receiving corticosteroid therapy. This result would be maintained regardless of the severity of type 2 CRSwNP inflammation, the volume of the polyps, or the patient's subjective symptomatology.

Assessment of olfactory recovery after COVID-19: cross-sectional study.

OBJECTIVE: This study aimed to evaluate recovery patterns of olfactory dysfunction among recovered COVID-19 patients, both subjective and objective, and correlate this recovery to the severity of the disease. METHODS: The study recruited 200 patients and assigned them to two equal groups, one of them was a control group. The olfactory function of the study group was assessed via subjective and objective methods at baseline and then monthly for three months, with changes in smell function reported at each visit. These patients underwent chemosensory testing using the Sniffin' Sticks test and completed the validated Arabic version of the Questionnaire of Olfactory Disorders-Negative Statements (QOD-NS). RESULTS: Olfactory dysfunction occurred on the first day of COVID-19 symptoms in 37% of participants. Subjective reports suggested smell recovery in 55% after 3 months, but Sniffin' Sticks showed only 1% with normal function, indicating persistent deficits in others. This study revealed smell recovery for 93% of participants (median 14 days), with most (58%) recovering within 2 weeks. No significant links were found between demographics, COVID-smell loss timing, and recovery speed. CONCLUSION: Three months after COVID-19, many patients perceive smell recovery, but objective tests reveal shockingly high rates of persistent dysfunction. Further follow-up with objective tests is vital to assess the true burden and potential long-term effects of smell loss.

One-year psychophysical evaluation of COVID-19-induced olfactory disorders: a prospective cohort study.

BACKGROUND: Olfactory disorders are common in COVID-19. While many patients recover within weeks, a notable number of patients suffer from prolonged olfactory disorders. Much research has focused on the acute phase of olfactory disorders in COVID-19; however, there is still inconsistency regarding the prognosis. We aim to assess both objective and subjective olfactory function in patients with persisting olfactory disorders following COVID-19, 1 year after diagnosis. METHODS: We objectively measured olfactory function in 77 patients who initially had COVID-19-induced smell disorders, 1 year after confirmed diagnosis. These patients previously underwent two objective measurements at approximately 3 and 6 months after COVID-19, in the context of the COCOS trial (COrticosteroids for COvid-19-induced loss of Smell). The main outcome measurement was TDI score (threshold-discrimination-identification) on Sniffin' Sticks Test (SST). Secondary outcomes included objective gustatory function on Taste Strip Test (TST), self-reported olfactory, gustatory and trigeminal function on a visual analogue scale (VAS) and outcomes on questionnaires about quality of life, and nasal symptoms. RESULTS: The findings of this study show that 1 year following COVID-19, the median TDI score increased to 30.75 (IQR 27.38-33.5), regarded as normosmia. The median TDI score started at 21.25 (IQR 18.25-24.75) at baseline and increased to 27.5 (IQR 23.63-30.0) at 6 months following COVID-19. The increase of 9.5 points on the TDI score between baseline and 1 year after COVID-19 marks a clinically relevant improvement. Regarding the self-reported VAS score (1-10) on sense of smell, it increased from 1.2 (IQR 0.4-3.0) at baseline to 3.2 (IQR 1.4-6.0) at 6 months and further improved up to 6.1 (IQR 2.7-7.5) after 1 year. Objective gustatory function increased with 2 points on TST a year after diagnosis. Self-reported olfactory, gustatory, and trigeminal functions also improved over time, as did quality of life. CONCLUSIONS: Objective and self-reported olfactory function continued to improve 1 year after COVID-19. The median TDI score of 30.75 (IQR 27.38-33.5) is regarded as normosmia, which is a favorable outcome. However, the rate of improvement on TDI score reduces over time.

Effects of Endoscopic Sinus Surgery on Olfactory Function.

PURPOSE OF REVIEW: To review the effects of endoscopic sinus surgery and endonasal approaches to the skull base on olfaction. RECENT FINDINGS: Advancements in endonasal endoscopic approaches to the sinuses and skull base allow for direct treatment of a variety of sinonasal and skull base diseases. However, these extended approaches will often require manipulation of normal anatomical structures and the olfactory neuroepithelium. Depending on the planned procedure and extent of disease, the prognosis of olfactory perception can vary significantly among patients. Endoscopic sinonasal surgical procedures may impact olfaction. Optimizing olfactory function requires proper surgical techniques, gentle handling of tissue, and perioperative care. Surgeons must discuss objectives and manage patient expectations. Routine olfactory assessment is crucial in surgical work-up and follow-up. Preserving anatomical structures while addressing the obstruction of the olfactory cleft helps to prevent decreased olfactory threshold. However, smell identification and discrimination do not always correlate with sinonasal anatomy.

Phantom smells: a prevalent COVID-19 symptom that progressively sets in.

PURPOSE: One of the long-term symptoms of COVID-19 is phantosmia, a type of Olfactory Disorder (OD) that has deleterious impacts on patients' quality of life. The aim of this article was to study how this poorly understood qualitative OD manifests itself in the COVID-19. METHODS: 4691 patients with COVID-19 responded to our online questionnaire focusing on COVID-19-related OD. We first analyzed the prevalence of phantosmia in this population. Then, with the help of Natural Language Processing techniques, we investigated the qualitative descriptions of phantom smells by the 1723 respondents who reported phantosmia. RESULTS: The prevalence of phantosmia was of 37%. Women were more likely to report phantosmia than men, as well as respondents for whom OD was described as fluctuating rather than permanent, lasted longer, was partial rather than total and appeared progressively rather than suddenly. The relationship between OD duration and phantosmia followed a logarithmic function, with a prevalence of phantosmia increasing strongly during the first 2 months of the disease before reaching a plateau and no decrease over the 15 months considered in this study. Qualitative analyses of phantosmia descriptions with a sentiment analysis revealed that the descriptions were negatively valenced for 78% of the respondents. Reference to "tobacco" was more frequent in non-smokers. Source names and odor characteristics were used differently according to age and OD duration. CONCLUSION: The results of this descriptive study of phantosmia contribute to the current efforts of the medical community to better understand and treat this rapidly increasing COVID-19-related OD.

Food-related experiences and behavioral responses among people affected by chemosensory dysfunctions following COVID-19: A scoping review.

A category of symptoms that became characteristic early in the first wave of the coronavirus disease 2019 (COVID-19) pandemic was chemosensory dysfunctions (alterations of smell and taste). Such symptoms substantially affect food and eating-cornerstones for both nutrition-related health outcomes and for quality of life. Based on this, this scoping review aimed to map out existing scientific literature on food-related experiences and related behavioral responses among people affected by chemosensory dysfunctions following COVID-19. A librarian-supported search of PsycInfo, PubMed, and Scopus for publications written in English (2020 to April 26, 2022) was conducted. Two authors searched for and screened publications and three others extracted and collated data. These are reported following the Preferred Reporting Items of Systematic reviews and Meta-Analyses extension for Scoping Reviews. Of 1169 hits, 9 publications were included in the review. The results are thematized as "Psychological and social aspects" and "Nutritional aspects," each with the subsections "Experiences" and "Behavioral responses." A great variety of food-related problems, nutritional and mental health effects, and implications for social life are identified. People affected by chemosensory dysfunctions following COVID-19 suffer, as evident both in stories from qualitative studies and in measurements of quality of life. The results impact all professions who are and may come to be involved in treating these patients, such as nurses, physicians, dietitians, and psychologists. With more knowledge about the dysfunctions' manifestation, duration, and impact on everyday life, multiprofessional teams need to collaborate in supporting patients medically, psychosocially, and nutritionally.

Olfactory Training Impacts Olfactory Dysfunction Induced by COVID-19: A Pilot Study.

INTRODUCTION: Olfactory dysfunction is one of the main symptoms of COVID-19 and may last beyond resolution of the infection. The most promising intervention for post-viral olfactory dysfunction is olfactory training (OT), which involves exposing the olfactory system to a range of odors daily. This approach is thought of promoting the regeneration of olfactory receptor cells, but its effectiveness in patients with post-COVID-19 olfactory dysfunction has yet to be confirmed. METHODS: This double-blind randomized pilot study compared the effectiveness of OT versus placebo in the treatment of post-COVID-19 olfactory dysfunction. Twenty-five participants were recruited in each group. OT protocol consisted of sniffing 4 scents (rose, orange, clove, and eucalyptus) for 5 min twice daily for 12 weeks. Olfactory function was assessed before and after the training using (1) a validated odor identification test (UPSIT-40) and (2) a 10-point visual analog scale; we further assessed the presence of (3) parosmia. RESULTS: While we did not observe any effect of OT on olfactory test scores, we observed a significant improvement of subjective olfactory function in the intervention group, while no such effect was observed in the placebo group. Finally, the frequency of parosmia was significantly lower in the intervention group. CONCLUSIONS: This study highlights an increase in subjective but not objective olfactory function when performing OT for 12 weeks. Further, parosmia seems to be positively affected by OT. These results may serve as a starting point for larger scale studies to assess the efficacy of OT for treatment of post-COVID-19 olfactory dysfunction.

Olfactory Disorders Questionnaire: Scaling severity of quality-of-life impact.

BACKGROUND: The Olfactory Disorders Questionnaire (ODQ) is widely used for patients suffering from olfactory disorders to depict the impact on quality of life. The aim of this study was to scale and produce reference values for patients ODQ score according to Becks Depression Inventory (BDI) severity. METHODS: In this prospective study, a cross-sectional anonymous survey was created, which combined EQ-5D-5L, BDI and ODQ. Correlation was calculated between the three questionnaires. Receiver operator characteristic curves were created to produce cut-off values for ODQ scores based on three BDI categories (mild, borderline clinical and moderate-to-severe depression). RESULTS: Of the 578 who responded to the survey, 445 completed all sections and were included in the study. Majority were female (n = 327,73.5%), median age group 55-70 years (n = 193,43.4%). There was a strong correlation between BDI score and total ODQ score. There was a clear gradient in total ODQ score for each BDI classification; those with mild depression had the lowest mean ODQ score (101.8, range 39-168), those with moderate-to-severe depression had the highest (138.24, range 74-177). Due to overlapping of confidence intervals we were unable to grade the ODQ score. CONCLUSION: The study was unable to generate reference values for the ODQ due to lower numbers of patients with borderline clinical to extreme depression. However, we were able to appreciate the general trend, that the higher the ODQ score, the higher the risk of depression. These findings should guide clinical practice to ensure appropriate care and support is provided for those with olfactory dysfunction.

Establishing UK research priorities in smell and taste disorders: A James Lind alliance priority setting partnership.

OBJECTIVES: To determine the top 10 research priorities in Smell and Taste Disorders (SATD). DESIGN: After steering group was established, an electronic survey was disseminated to determine the list of questions. After removing out-of-scope responses, the remainder were consolidated to create summary questions. A literature search was conducted to remove already answered questions. A second survey was used to determine the top questions that formed the subject of final debate at a workshop attended by clinicians and patients to determine the top 10 priorities. SETTING: A James Lind Alliance Priority Setting Partnership (JLAPSP) was established by FifthSense to identify the top 10 research questions in SATDs in the United Kingdom. PARTICIPANT: All stakeholders in SATDs (patients, healthcare professionals, family, carers, researchers). MAIN OUTCOME MEASURES: Final 10 research priorities. RESULTS: The 665 respondents to the initial survey provided 1698 research questions. Thirteen were out-of-scope and removed; remaining 1685 were then consolidated to form 147 summary questions. Following literature search and discussion with the steering group, 37 questions remained for the second survey, which 235 people responded. The top ten priorities agreed upon in the workshop covered themes of improved understanding of pathophysiologlogy, improving health services, and managing long-term effects of smell/taste disorders. The most important research question agreed was "How can we further our understanding of the mechanism of disease in the nerve pathways that affect smell and taste disorders, including where parosmia and phantosmia exist." CONCLUSION: We report the top 10 research priorities in smell and taste disorders. These priorities will now empower researchers to secure research funding and provide the basis of the FifthSense research hub.

Impact of deep brain stimulation (DBS) on olfaction in Parkinson's disease: Clinical features and functional hypotheses.

Deep brain stimulation (DBS) is a surgical therapy typically applied in Parkinson's disease (PD). The efficacity of DBS on the control of motor symptoms in PD is well grounded while the efficacity on non-motor symptoms is more controversial, especially on olfactory disorders (ODs). The present review shows that DBS does not improve hyposmia but can affect positively identification/discrimination scores in PD. The functional hypotheses suggest complex mechanisms in terms of cerebral connectivity and neurogenesis process which could act indirectly on the olfactory bulb and olfactory pathways related to specific cognitive olfactory tasks. The functional hypotheses also suggest complex mechanisms of cholinergic neurotransmitter interactions involved in these pathways. Finally, the impact of DBS on general cognitive functions in PD could also be beneficial to identification/discrimination tasks in PD.

q-Powders: a quick test for screening retronasal olfactory disorders with tasteless powders.

PURPOSE: To investigate the clinical utility of q-Powders-a retronasal identification screening test. METHODS: A total of 156 subjects (92 females, mean age: 54.5 years ± 17.3 years) completed a 3-item q-Powders retronasal identification test and a 16-items Sniffin' Sticks orthonasal identification test. We analyzed whether the q-Powders test could differentiate between subjects with normosmia and subjects with an olfactory disorder. RESULTS: Our data indicated that subjects with an olfactory disorder scored lower in the q-Powders test than subjects with normosmia. The analyses revealed q-Powders test sensitivity of 84% and a test specificity of 64.9% with a score of 2 points taken as a cutoff for olfactory disorders. CONCLUSION: The 3-item q-Powders retronasal test may be used for screening purposes in clinical research. LEVEL OF EVIDENCE: 4.

Clinical Olfactory Working Group consensus statement on the treatment of postinfectious olfactory dysfunction.

BACKGROUND: Respiratory tract viruses are the second most common cause of olfactory dysfunction. As we learn more about the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the recognition that olfactory dysfunction is a key symptom of this disease process, there is a greater need than ever for evidence-based management of postinfectious olfactory dysfunction (PIOD). OBJECTIVE: Our aim was to provide an evidence-based practical guide to the management of PIOD (including post-coronavirus 2019 cases) for both primary care practitioners and hospital specialists. METHODS: A systematic review of the treatment options available for the management of PIOD was performed. The written systematic review was then circulated among the members of the Clinical Olfactory Working Group for their perusal before roundtable expert discussion of the treatment options. The group also undertook a survey to determine their current clinical practice with regard to treatment of PIOD. RESULTS: The search resulted in 467 citations, of which 107 articles were fully reviewed and analyzed for eligibility; 40 citations fulfilled the inclusion criteria, 11 of which were randomized controlled trials. In total, 15 of the articles specifically looked at PIOD whereas the other 25 included other etiologies for olfactory dysfunction. CONCLUSIONS: The Clinical Olfactory Working Group members made an overwhelming recommendation for olfactory training; none recommended monocycline antibiotics. The diagnostic role of oral steroids was discussed; some group members were in favor of vitamin A drops. Further research is needed to confirm the place of other therapeutic options.

A New Mystery: Phantosmia after COVID-19 Infection.

Coronavirus disease 2019 (COVID-19) has developed as a pandemic and has caused millions of deaths worldwide. Multiple studies have implicated anosmia and ageusia as symptoms associated with COVID-19. In this case report we present the cases who suffer from phantosmia after COVID-19 infection. As the prevalence of the virus increases, the symptomatology profile continues to be updated. More studies are needed to better understand this disease.

Frequency and Severity of Ear-Nose-Throat (ENT) Symptoms during COVID-19 Infection.

Background and Objectives: Coronavirus disease 2019 (COVID-19) is a new disease entity caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main symptoms of infection at the onset of the pandemic include dyspnea, cough and high fever. Ear−nose−throat (ENT) symptoms are among the ones presented by patients in the course of infection. The aim of the study was to analyze the frequency of ENT symptoms and to assess their severity and duration in COVID-19 patients. Materials and Methods: The study included 337 patients who had been infected with SARS-CoV-2, as confirmed by a PCR test. The study participants were >18 years old; the mean age was 43.98 years ± 13.47 SD. The convalescents completed a questionnaire that contained 26 questions, including 9 detailed questions related to ENT symptoms, such as sore throat, vertigo, dizziness, hearing disorders, olfactory disorders, taste disturbance, headache, cough and dyspnea. The severity of symptoms was assessed using a Visual Analogue Scale (VAS). Results: The most reported ENT symptoms were olfactory disorders, which occurred in 72% of patients. The second most frequent symptom was taste disturbance (68%), VAS = 6.79 ± 3.01. Vertigo and dizziness were reported by 34% of respondents (VAS = 4.01 ± 2.01). Tinnitus was observed in 15% of patients, VAS = 3.87 ± 1.98; 14% of the subjects reported hearing impairment (VAS = 3.81 ± 2.37). Conclusions: Symptoms related to the sense of smell, taste and hearing are some of the most common symptoms in the course of COVID-19, which is important in the therapeutic and epidemiological management of patients. Delayed diagnosis and treatment of symptoms, especially those related to the hearing organ, may result in greater permanent damage.

Loss of Taste and Smell as Distinguishing Symptoms of Coronavirus Disease 2019.

In a household study, loss of taste and/or smell was the fourth most reported symptom (26/42 [62%]) among coronavirus disease 2019 (COVID-19) case patients and had the highest positive predictive value (83% [95% confidence interval [CI], 55%-95%) among household contacts. Olfactory and taste dysfunctions should be considered for COVID-19 case identification and testing prioritization.

Validation study of a novel approach for assessment of retronasal olfactory function with combination of odor thresholds and identification.

PURPOSE: The present study aimed to establish a test battery for the clinical assessment of retronasal odor thresholds and retronasal odor identification. STUDY DESIGN: Prospective case-control series. METHODS: Sixty participants (36 women, 24 men, mean age 37.6 ± 19.4 years) were enrolled in this study; 36 were healthy controls and 24 were patients with olfactory dysfunction. Orthonasal olfactory function was assessed with the "Sniffin' Sticks" test battery. Retronasal olfaction was assessed with oral odorant delivery using special containers for threshold function, and with oral tasteless powders for odor identification. RESULTS: Retronasal and orthonasal olfaction were significantly correlated for threshold scores, identification score, and the sum of threshold and identification score (TI score). Validity analyses showed that the retronasal TI score was able to discriminate between healthy controls and patients with olfactory dysfunction. CONCLUSIONS: Normosmic participants can be distinctly differentiated from patients with olfactory dysfunction using a valid test battery comprised of retronasal threshold and identification tests. Based on the current findings, we advocate a TI score of 16 as a cut-off between patients and controls. Therefore, TI scores of 17 and above would indicate retronasal normosmia.

Pleasant parosmia with regard to own stool after SARS-CoV-2 infection.

Coronavirus disease 2019 (COVID-19) has had a significant global impact due to the millions of deaths it has caused secondary to respiratory failure. However, the disease has also been associated with a wide array of manifestations in other organ systems. Among them, the presence of anosmia, which occurs in up to half the patients, has become a new sign of alarm to suspect the infection. Although up to 90% of affected patients will experience an improvement of their olfactory alterations within a month after the infection, the variety and severity of olfactory disturbances clearly cannot be summarized by the dichotomy of having anosmia or not. Parosmias are a type of olfactory dysfunction characterized by altered perception of odors, which can reflect both damage at some level of the olfactory tract, as well as the possibility of reversibility of said damage. The present manuscript describes possible olfactory disturbances associated with COVID-19, their pathophysiology, and potential clinical significance.

La enfermedad por coronavirus 2019 (COVID-19) ha tenido un impacto mundial trascendente por los millones de muertes que ha causado secundarias a insuficiencia respiratoria. Sin embargo, la enfermedad también se ha asociado a una amplia gama de manifestaciones en otros sistemas. Entre ellas, la presencia de anosmia, la cual ocurre en hasta mitad de los pacientes, se ha vuelto un nuevo dato de alarma para sospechar la infección. Aunque hasta el 90% de los pacientes afectados presentarán mejoría de sus alteraciones olfatorias dentro del mes posterior a su cuadro, la variedad y gravedad de alteraciones olfatorias claramente no pueden resumirse en la dicotomía de tener o no anosmia. Las parosmias son un tipo de alteración olfatoria caracterizadas por percepciones alteradas de los olores, las cuales pueden reflejar tanto daño a algún nivel del tracto olfatorio, así como la posibilidad de reversibilidad de dicho daño. En el presente manuscrito se describen las posibles alteraciones olfatorias asociadas a COVID-19, su fisiopatología, y potencial significancia clínica.

Smell-Based Memory Training: Evidence of Olfactory Learning and Transfer to the Visual Domain.

Human and non-human animal research converge to suggest that the sense of smell, olfaction, has a high level of plasticity and is intimately associated with visual-spatial orientation and memory encoding networks. We investigated whether olfactory memory (OM) training would lead to transfer to an untrained visual memory (VM) task, as well as untrained olfactory tasks. We devised a memory intervention to compare transfer effects generated by olfactory and non-olfactory (visual) memory training. Adult participants were randomly assigned to daily memory training for about 40 days with either olfactory or visual tasks that had a similar difficulty level. Results showed that while visual training did not produce transfer to the OM task, olfactory training produced transfer to the untrained VM task. Olfactory training also improved participants' performance on odor discrimination and naming tasks, such that they reached the same performance level as a high-performing group of wine professionals. Our results indicate that the olfactory system is highly responsive to training, and we speculate that the sense of smell may facilitate transfer of learning to other sensory domains. Further research is however needed in order to replicate and extend our findings.

Olfactory Dysfunction in a Mexican Population Outside of COVID-19 Pandemic: Prevalence and Associated Factors (the OLFAMEX Study).

PURPOSE OF REVIEW: To study the prevalence of olfactory loss and its associated factors in a Mexican population a cross-sectional analytical study based on a population interviewed about health, epidemiologic aspects, and sense of smell (tested with four scents: rose, banana, perfume, and gas) was conducted to evaluate olfactory detection, memory, and identification. Levels of sense of smell perception were determined when the participants detected, recognized, or identified all (normosmia), 1-3 (hyposmia), or none (anosmia) of the odorants. Associated factors of olfactory dysfunction were identified by multivariate analysis (odds ratio, 95%CI). RECENT FINDINGS: Olfactory dysfunction is a prevalent disorder affecting up to 20% of the general population. In addition to viral infection, including COVID-19, a number of other causes and factors may also be involved. 1,956 surveys were conducted and 1,921 were analyzed. Most of the participants (62.1%) were women. The general prevalence of olfactory dysfunction, regarding detection, was 7.2% (7.1% hyposmia, 0.1% anosmia). Age-related olfactory deterioration was observed in both sexes from the 5th decade of life (OR 2.74, p = 0.0050). Women showed better olfactory identification (OR 0.73, p = 0.0010). Obesity (OR 1.97, p = 0.0070), low educational level, bad/very bad self-perceived olfactory function (OR 2.74, p = 0.0050), olfactory loss for less than one week (OR 1.35, p = 0.0030), exposure to toxics/irritants (OR 1.31, p = 0.0030), active smoking (OR 1.58, p < 0.0010), and type 2 diabetes mellitus (OR 2.68, 95%CI 1.74-4.10, p < 0.0001) were identified as factors associated with olfactory dysfunction. These results in a Mexican population suggest better olfactory identification (verbalization) in females. Age was a determining factor in the olfactory deterioration process and obesity and diabetes mellitus were also associated with olfactory disorders. Finally, these findings reinforce the differential diagnosis with other potential causes of sense of smell loss, during the COVID-19 outbreak.