BACKGROUND:  Olfactory training (OT) is commonly used for the treatment of olfactory disorders. Nevertheless, there is an ongoing debate about the most effective OT regimen. We aimed to compare the effects of OT with 7 items (rose, lemon, eucalyptus, cloves, stewed apple, balm, mint) to 4-item-OT (rose, lemon, eucalyptus, cloves) over 3 months. Methods: Participants were 40 patients with olfactory dysfunction receiving 4-item-OT or 7-item-OT and 60 gender- and age-matched individuals with normal sense of smell receiving no OT, 4-item-OT, or 7-item-OT. Before and after the OT we assessed n-butanol odor thresholds, discrimination, and identification (TDI score), additionalthresholds for (R)-(-)-carvone, β-damascenone, salicyclic acid benzylester, the degree of phantosmia and parosmia, cognitive function, and ratings of olfactory function. Results: In both patient groups, the TDI score increased with the use of OT, regardless of the number of odors used (p < 0.001; 3.48 ± 4.21 and lower than control groups). The clinically significant increase of 5.5 points in TDI score correlated with change of ratings of parosmia (r 0.62; p < 0.01) and with ratings of olfactory dysfunction (r = 0.51; p < 0.05).
CONCLUSIONS:  Concluding, OT over a 3-months period with 4 or 7 odors appears to produce similar results, although the sample size has to be considered.

OBJECTIVE: Olfactory training (OT) is an effective and affordable option in the treatment of olfactory dysfunction. Despite significant progress in the field in recent years, some factors influencing OT participation remain unclear.
METHODS: Based on an anonymous online survey orchestrated by AbScent.org the present study enrolled 450 participants and divided them into OT (n = 161) and No OT (n = 289) groups based on their OT participation. Participants also provided information on demographics, medical history, quality of life, OT duration for those who engaged in OT, and the reasons for non-participation in OT among those who did not.
RESULTS: Patients who had greater loss of quality of life participated more in OT. Similarly, more participation was observed in patients who noticed an improvement in their ability to smell. Notably, most of the sample engaged in OT trained less than four weeks (73%). In the No OT group, the primary barrier to OT participation was the unawareness of OT treatment (37%) and these barriers differed by age, where older people expressed interest but were unaware of OT treatment, while younger individuals exhibited more cautiousness about its effectiveness.
CONCLUSIONS: Lower quality of life drives active OT participation. Limited training periods and unawareness of OT serve as potential barriers to olfactory recovery. Clinicians should actively promote the background of OT and underscore the significance of adhering to the \"prescribed\" training regimen.

OBJECTIVE: This study aims to highlight the feasibility of an olfactory training program entirely monitored through online media in COVID-19 patients.
METHODS: Classic olfactory training was performed with a sample with olfactory loss due COVID-19 (n = 11). Participants were engaged on a weekly video call in order to improve adherence and collect information regarding the number of correct answers and the individuals\' perception of olfactory function. The olfactory status after training was compared to two groups, one composed of participants who contracted COVID-19 but did not report olfactory loss (n = 11) and a sample composed of healthy participants (n = 11).
RESULTS: The experimental group showed improvements throughout the training period (TDI score on week 0 was 20.3 (5.6) and 24.6 (4.3) for week 12, and on week 24 was 25.4 (6.2) (F = 5.115, df = 2, 20, p = 0.016), and post hoc tests showed that participants significantly improved their TDI score in W12 compared to W0 (SMD = 0.869, p = 0.041) and in W24 compared to W0 (SMD = 0.859, p = 0.041). The experimental group showed lower scores when compared with both groups, and the no OT COVID-19 group showed lower scores than the healthy control group, even though they did not report olfactory alterations.
CONCLUSIONS: Findings suggest that the strategies applied to improve adherence were successful since 100% of the sample completed the training adherence, offering a valuable framework for future olfactory training studies.

Approximately 30-60% of people suffer from olfactory dysfunction (OD) such as hyposmia or anosmia after being diagnosed with COVID-19; 15-20% of these cases last beyond resolution of the acute phase. Previous studies have shown that olfactory training can be beneficial for patients affected by OD caused by viral infections of the upper respiratory tract. The aim of the study is to evaluate whether a multisensory olfactory training involving simultaneously tasting and seeing congruent stimuli is more effective than the classical olfactory training. We recruited 68 participants with persistent OD for two months or more after COVID-19 infection; they were divided into three groups. One group received olfactory training which involved smelling four odorants (strawberry, cheese, coffee, lemon; classical olfactory training). The other group received the same olfactory stimuli but presented retronasally (i.e., as droplets on their tongue); while simultaneous and congruent gustatory (i.e., sweet, salty, bitter, sour) and visual (corresponding images) stimuli were presented (multisensory olfactory training). The third group received odorless propylene glycol in four bottles (control group). Training was carried out twice daily for 12 weeks. We assessed olfactory function and olfactory specific quality of life before and after the intervention. Both intervention groups showed a similar significant improvement of olfactory function, although there was no difference in the assessment of quality of life. Both multisensory and classical training can be beneficial for OD following a viral infection; however, only the classical olfactory training paradigm leads to an improvement that was significantly stronger than the control group.

Introduction Persistent olfactory dysfunction was seen in many patients upon coronavirus disease 2019 (COVID-19) infection recovery. However, research on its management was very limited, especially among the Southeast Asian population. Objectives We aim to investigate the role of olfactory rehabilitation and topical corticosteroids among post-COVID-19 olfactory dysfunction patients in Malaysia, and at the same time to determine factors leading to olfactory recovery post-COVID-19 infection. Methods Adult Malaysians with persistent olfactory dysfunction one month post-COVID-19 recovery were recruited. Thirty-one patients were randomly assigned into three groups with 10 patients being given olfactory training (Group 1), another 10 being given mometasone furoate nasal spray/olfactory training (Group 2), and 11 patients being assigned to the control group (Group 3). All groups were followed up for an average duration of six months. Olfactory function was evaluated by Top International Biotech Smell Identification Test (TIBSIT) scores and Olfactory Disorder Questionnaire (eODQ) prior to randomization, at three and six months after recruitment. Results The baseline characteristics of patients were similar in all groups. Generally, patients of all three groups showed a statistically significant improvement in the TIBSIT scores after six months. The TIBSIT scores for Group 2 were statistically significantly higher than the control at three months but not at six months. As for Group 1, no statistically significant differences in TIBSIT scores at both three and six months were noted when compared to control. Statistically significant improvements were seen in the eODQ scores in all three groups. Conclusion No superiority of intervention for post-COVID-19 olfactory dysfunction was seen compared to control.

OBJECTIVE: The new corona virus infection, has a wide range of clinical manifestations. Fever and cough are the most common symptoms. The olfactory function may be also affected with COVID-19. In this randomized clinical trial, we wanted to evaluate the therapeutic effect of olfactory training with and without oral vitamin A for COVID-19-related olfactory dysfunction.
METHODS: Patients answered to the standard Persian version of anosmia reporting tool and performed the quick smell test before and after 12 weeks and at the end of the 12 months follow up. The patients were randomly allocated to three groups; Group A treatment with olfactory training, Group B treatment with oral vitamin A and olfactory training, and Group C as control group which only underwent nasal irrigation twice a day. Patients were treated for 3 months and followed up for 12 months.
RESULTS: Totally 90 patients were included in three groups. After interventions, 76.9% of patients in Group A, 86.7% of patients in Group B, and 26.7% of patients in Group C completely improved. The average intervention time was statistically significant in relationship with the final olfactory status of the patients in the 12 months follow-up. The olfactory training has significantly improved the smell alteration at the end of 3- and 12- months follow-up in A and B groups.
CONCLUSIONS: A three-months olfactory training is effective for improvement of COVID-19-related olfactory dysfunction. Adding daily oral vitamin A to olfactory training did not lead to better results in improving olfactory dysfunction.
METHODS: Step 2 (Level 2*): Randomized trial.

BACKGROUND: This longitudinal prospective study aims to investigate the potential of circulating calprotectin (cCLP) as a biomarker in persistent olfactory dysfunctions following COVID-19 infection.
METHODS: Thirty-six patients with persistent hyposmia or anosmia post COVID-19 were enrolled (HT0) and re-evaluated after three months of olfactory training (HT1). Two control groups included 18 subjects without olfactory defects post COVID-19 (CG1) and 18 healthy individuals (CG2). Nasal brushing of the olfactory cleft and blood collection were performed to assess circulating calprotectin levels.
RESULTS: Higher calprotectin levels were observed in serum and nasal supernatant of hyposmic patients (HT0) compared to control groups (CG1 and CG2). Post-olfactory training (HT1), olfactory function improved significantly, paralleled by decreased calprotectin levels in serum and nasal samples. Circulating calprotectin holds potential as a biomarker in persistent olfactory dysfunctions after COVID-19. The decrease in calprotectin levels post-olfactory training implies a role in monitoring and evaluating treatment responses.
CONCLUSIONS: These findings contribute to the growing literature on potential biomarkers in post-COVID-19 olfactory dysfunctions and underscore the importance of investigating novel biomarkers for personalized patient management. Nevertheless, further studies are needed to validate the application of calprotectin assay in nasal diseases and its correlation with nasal cytology.

UNASSIGNED: Olfactory disorders significantly affect individuals, diminishing their capacity to detect dangers, appreciate flavors, and engage socially. Despite their considerable impact on quality of life, these disorders often receive less attention compared to other sensory impairments. This review emphasizes the importance of olfactory function and explores both traditional and innovative diagnostic and therapeutic approaches.
UNASSIGNED: This review comprehensively covers the pathophysiology, diagnostic challenges, and treatment options for olfactory disorders. It delves into the nuances of different disorders, such as anosmia and parosmia, and discusses the array of diagnostic tools from traditional sniff tests to advanced imaging techniques. The review also evaluates therapeutic strategies, from pharmacological treatments to emerging therapies like electrical stimulation and regenerative medicine, highlighting recent advances in the field.
UNASSIGNED: Current insights suggest a growing recognition of the significance of olfactory disorders, driven by recent pandemics and advances in diagnostic and therapeutic technologies. Future perspectives indicate a promising direction toward more personalized medicine approaches and enhanced regenerative therapies. Continuous research and improved clinical awareness are critical for evolving the management strategies of olfactory impairments, potentially leading to better patient outcomes and quality of life enhancements.

UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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).
UNASSIGNED: 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.
UNASSIGNED: Level 3.

OBJECTIVE: 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.
CONCLUSIONS: Olfactory training was found to have a positive and significant effect on rehabilitating the olfactory function.