Effects Of Olfactory Training Research Articles

Four odorants for olfactory training are enough: a pilot study

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). Conclusion: 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.

Olfactory dysfunction and training in children with COVID-19 infection: A prospective study Post-COVID pediatric olfactory training

ObjectivePostviral olfactory dysfunction (OD) including corona 2019 viral disease (COVID-19) OD occurs in both adults and children. Despite limited reports of efficacy in treating adult postviral including COVID-19 OD with olfactory training (OT), its effects on children in general, and post-COVID-19 in specific, is unknown. The study aimed at evaluating the effects of OT in a COVID-19 OD pediatric cohort. MethodsA single-arm prospective study of pediatric COVID-19 OD subjects confirmed by the University of Pennsylvania Smell Identification Test (UPSIT), was conducted. All subjects underwent OT by sniffing 4 odorants (lavender, orange, peppermint, and eucalyptus) for 1 min twice a day for 3 months. Subjects underwent an odorant identification test (OIT) of the 4 odorants each visit. A repeat UPSIT was administered at the 4th visit. ResultsThe study enrolled a total of 37 subjects [11 males/26 females with mean age/standard deviation (std) of 15.6(2.1) years]. The time interval between COVID-19 and entry was 5.3(2.4) months. The mean pre/post study UPSIT score improvement was 2.3(4.7), p = .09. OIT scores between entry and 3 subsequent visits showed a mean improvement of 1.8(1.5), 1.8(1.9) and 2.3(1.9) odorants, respectively, with P < .001 for all 3 comparisons. ConclusionsOT subjects were predominantly female teens with substantial OD lasting greater than 5 months. OT did not affect OD as measured by UPSIT but OIT scores improved during OT. We postulate that OT likely has a role in pediatric post-COVID OD recovery, but UPSIT likely is too rigid to detect disparate odorant improvement.

Olfactory training effects in children after mild traumatic brain injury

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.

Clinical effectiveness of rehabilitation in ambulatory care for patients with persisting symptoms after COVID-19: a systematic review

BackgroundLingering symptoms after acute COVID-19 present a major challenge to ambulatory care services. Since there are reservations regarding their optimal management, we aimed to collate all available evidence on the effects of rehabilitation treatments applicable in ambulatory care for these patients.MethodsOn 9 May 2022, we systematically searched articles in COVID-19 collections, Embase, MEDLINE, Cochrane Library, Web of Science, CINAHL, PsycArticles, PEDro, and EuropePMC. References were eligible if they reported on the clinical effectiveness of a rehabilitation therapy applicable in ambulatory care for adult patients with persisting symptoms continuing 4 weeks after the onset of COVID-19. The quality of the studies was evaluated using the CASP cohort study checklist and the Cochrane Risk of Bias Assessment Tool. Summary of Findings tables were constructed and the certainty of evidence was assessed using the GRADE framework.ResultsWe included 38 studies comprising 2,790 participants. Physical training and breathing exercises may reduce fatigue, dyspnoea, and chest pain and may improve physical capacity and quality of life, but the evidence is very weak (based on 6 RCTs and 12 cohort studies). The evidence underpinning the effect of nutritional supplements on fatigue, dyspnoea, muscle pain, sensory function, psychological well-being, quality of life, and functional capacity is very poor (based on 4 RCTs). Also, the evidence-base is very weak about the effect of olfactory training on sensory function and quality of life (based on 4 RCTs and 3 cohort studies). Multidisciplinary treatment may have beneficial effects on fatigue, dyspnoea, physical capacity, pulmonary function, quality of life, return to daily life activities, and functional capacity, but the evidence is very weak (based on 5 cohort studies). The certainty of evidence is very low due to study limitations, inconsistency, indirectness, and imprecision.ConclusionsPhysical training, breathing exercises, olfactory training and multidisciplinary treatment can be effective rehabilitation therapies for patients with persisting symptoms after COVID-19, still with high uncertainty regarding these effects. These findings can guide ambulatory care practitioners to treat these patients and should be incorporated in clinical practice guidelines. High-quality studies are needed to confirm our hypotheses and should report on adverse events.

The effect of olfactory training in patients with sensorineural and mixed type smell dysfunctions.

The effect of olfactory training in patients with sensorineural and mixed type smell dysfunctions.

The effect of olfactory training in patients with traumatic anosmia

The effect of olfactory training in patients with traumatic anosmia

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.

Clinical Features Assessment and Effect of Olfactory Training among COVID-19 Patients in the Kingdom of Saudi Arabia

Coronavirus disease (COVID-19) was announced in Mar 2020 as a global pandemic. Olfactory dysfunction (OD) is a common consequence. Therefore, the present study assessed the prevalence of OD and other clinical features among COVID-19 patients in Saudi Arabia along with the effect of olfactory training. Eighty-two patients participated in this study and their demographics as well as clinical features, effect of olfactory training, and recovery time were assessed using a questionnaire. Patients with OD went through self olfactory training by sniffing essential oils twice a day for 30 or 40 sec, followed by 10 or 20 sec break then repeat for 5 or 10 min for 6 weeks. Our results revealed that 62% had OD in which 41% had hyposmia and 21% had anosmia, while 38% had normosia. Additionally, 80% lost their olfactory function during infection period, whereas 20% lost it post-infection. Most patients recovered their olfactory function after 2 weeks (39%). Moreover, 71% restored their olfactory function naturally, whilst 27% restored it by olfactory training, and 2% did not experience improvement. The frequently reported symptoms among OD patients included headache (62%), sore throat (60%), fever (54%), and cough (48%). Whereas the common symptoms among patients without OD are bone pain (38%), diarrhea (24%) anorexia (21%), and vomiting (11%). This study highlights the prevalence and underlying mechanism of OD and the potential effect of olfactory training using essential oils due to their unharmful bioactive molecules. The likely of OD makes it a recommended diagnostic tool in early COVID-19 stage.

Effectiveness of olfactory training in COVID-19 patients with olfactory dysfunction: a prospective study.

ObjectivesTo investigate effectiveness of olfactory training (OT) in COVID-19 patients with persistent olfactory dysfunction (OD).MethodsFrom March 2020 to March 2022, COVID-19 patients with OD were prospectively followed in three European medical centers for a period of 18 months. A standardized OT protocol were recommended to patients. Patient-reported outcome questionnaires and psychophysical evaluations were used to evaluate olfaction at baseline, 6, 12, and 18 months after the start of OT. The evolution of olfactory outcome was compared according to the adherence to the OT protocol.ResultsFifty-seven patients completed the evaluations. Thirty-two patients fully adhered to the OT, while 25 did not adhere. The psychophysical scores significantly improved from baseline to 6-month post-infection in both groups. In the OT group, the psychophysical scores continued to significantly improve from 6 to 12 months after the start of OT (p = 0.032). The mean duration of OT was 15.4 weeks. The mean delay of patient recovery perception was comparable between groups (27.4 weeks). The occurrence of cacosmia (35.1%) and parosmia (43.9%) throughout the follow-up period was comparable between groups. There proportion of phantosmia was higher in training (34.4%) compared with no-OT (16.0%; p = 0.007) group. The baseline Sniffin’Sticks tests was positively associated with the 6-month Sniffin’Sticks tests (rs = 0.685; p < 0.001) and negatively associated with the time of recovery (rs = − 0.369; p = 0.034).ConclusionsThe adherence to an OT protocol was associated with better mid-term improvement of psychophysical scores. Future large-cohort randomized-controlled studies are needed to confirm the effectiveness of OT in COVID-19 patients.

Effect of Olfactory Training on Restoring Smell and Taste Senses Post Covid-19 Infection

Effect of Olfactory Training on Restoring Smell and Taste Senses Post Covid-19 Infection

The Effect of Olfactory Training on Olfaction, Cognition, and Brain Function in Patients with Mild Cognitive Impairment.

The olfactory system is affected very early in Alzheimer's disease and olfactory loss can already be observed in patients with mild cognitive impairment (MCI), an early stage of AD. The aim of this randomized, prospective, controlled, blinded study was to evaluate whether olfactory training (OT) may have an effect on olfactory function, cognitive impairment, and brain activation in MCI patients after a 4-month period of frequent short-term exposure to various odors. A total of 38 MCI outpatients were randomly assigned to OT or a control training condition, which were performed twice a day for 4 months. Olfactory testing, comprehensive neuropsychological assessment, and a passive odor perception task based on magnetic resonance imaging were performed before and after training. The results suggested that OT exhibited no significant effect on olfaction and cognitive function. Additionally, OT exhibited a positive effect on frontal lobe activation (left middle frontal gyrus and orbital-frontal cortex) but exhibited no effect on grey matter volume. Moreover, the change of olfactory scores was positively associated with the change of frontal activation. OT was found to have a limited effect on olfaction and cognition in patients with MCI compared to a non-OT condition but increased their functional response to odors in frontal area.

Improved Odor Identification Ability and Increased Regional Gray Matter Volume After Olfactory Training in Patients With Idiopathic Olfactory Loss.

Idiopathic olfactory loss (IOL) is thought as an early marker for neurodegenerative disease. This study investigated the effect of olfactory training (OT) on regional gray matter volume (GMV) among patients with IOL. A total of 24 patients (mean age 64.6 years, 11 male) with IOL and 30 control participants with normal olfaction (mean age 62.6 years, 13 males) were included in the study. Voxel-based morphometry was performed to compare the GMV between patient and control groups. Only the patients received OT (averaged duration 7 months), and a longitudinal approach was used to examine the GMV change from pre- to post-OT. Moreover, the effect of OT on GMV change was explored for patients with different severity of olfactory loss (anosmia vs. hyposmia). Olfactory performance was measured alongside using the “Sniffin’ Sticks.” Patients had improved odor identification and larger GMV in the bilateral cerebellum, bilateral thalamus, left precentral gyrus, right gyrus rectus, and medial orbitofrontal cortex after OT. However, no correlation was found between changes of odor identification and increased regional GMV. Besides, patients with anosmia, compared with patient with hyposmia, demonstrated increased GMV in the left precuneus, left superior frontal medial cortex, and left midcingulate cortex after OT. The study showed improved odor identification ability among patients with IOL after OT, which is unlikely related to spontaneous recovery. In this specific patient group, the GMV alterations may be associated with factors not directly predicted by the currently performed measurements, but possibly higher order olfactory-related functional changes.

Smell disorders in COVID-19 patients: role of olfactory training: A protocol for systematic review and meta-analysis.

Background:As the coronavirus disease 2019 (COVID-19) spread around the world, a surge of evidence suggests that smell disorders are common symptoms in COVID-19 infection. This dysfunction may cause loss of appetite, malnutrition, poisoning, and depression. Obviously, the impairment has a strong impact on the quality of life. Therefore, there is an urgent need to identify effective treatments. Various therapies have been studied to treat smell disorders after infection, and olfactory training (OT) is considered a promising treatment option. Assessing the effectiveness and safety of olfactory training for COVID-19 patients with smell disorders is the main purpose of this systematic review protocol.Methods:PubMed, EMBASE, MEDLINE, the Cochrane Library, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, Wanfang Database, ClinicalTrials.gov trials registry, and Chinese Clinical Trial Registry will be searched from January 2019 to January 2021. A combination of subject words and free text words will be applied in the searches. The language is limited to Chinese and English. The complete process will include study selection, data extraction, risk of bias assessment, and meta-analyses. Endnote X9.3 will be used to manage data screening. The statistical analysis will be completed by Review Manager V.5.3 (Cochrane Collaboration) or Stata V.16.0 software.Results:This proposed study will assess the effectiveness and safety of OT for COVID-19 patients with smell disorders.Conclusion:The conclusion of this study will provide evidence to prove the effectiveness and safety of olfactory training for COVID-19 patients with smell disorders.Ethics and dissemination:This protocol will not evaluate individual patient information or infringe patient rights and therefore does not require ethical approval.Registration:PEROSPERO CRD42020218009.

Factors associated with relevant olfactory recovery after olfactory training: a retrospective study including 601 participants.

Olfactory training (OT) represents a therapeutic option for multiple etiologies of olfactory dysfunction (OD) that also benefits normosmic subjects. In this retrospective study, we report the effectiveness of OT and factors associated with relevant changes in olfactory function (OF) in large groups of normosmic participants and patients with OD, including a control group that performed no training. This was a retrospective pooled analysis including 2 treatment cohorts of 8 previously published studies. Adult participants that either presented with the major complaint of quantitative OD or normosmic volunteers were recruited at various ENT clinics and received OT or no training. The outcome was based on changes in objective olfactory test scores after OT. A total of 601 patients with OD or normosmic subjects were included. OT was more effective compared to no training. No interaction was found between OT and OF. In multivariate analysis, higher baseline OF (adjusted odds ratio, aOR, 0.93) and posttraumatic (aOR, 0.29) or idiopathic OD (aOR, 0.18) compared to postinfectious causes were significantly associated with lower odds of relevant improvements in patients with OD receiving OT. Subgroup analysis of normosmic participants receiving OT further revealed a significant association of lower age and baseline olfactory function with improvements of overall OF. This study demonstrated that OT was more effective than no training in patients with various causes of OD. Additionally, baseline olfactory performance and etiology of OD were identified as important factors associated with relevant improvements after OT.

Factors associated with relevant olfactory recovery after olfactory training: a retrospective study including 601 participants.

Olfactory training (OT) represents a therapeutic option for multiple etiologies of olfactory dysfunction (OD) that also benefits normosmic subjects. In this retrospective study, we report the effectiveness of OT and factors associated with relevant changes in olfactory function (OF) in large groups of normosmic participants and patients with OD, including a control group that performed no training. This was a retrospective pooled analysis including 2 treatment cohorts of 8 previously published studies. Adult partici- pants that either presented with the major complaint of quantitative OD or normosmic volunteers were recruited at various ENT clinics and received OT or no training. The outcome was based on changes in objective olfactory test scores after OT. A total of 601 patients with OD or normosmic subjects were included. OT was more effective compared to no training. No interaction was found between OT and OF. In multivariate analysis, higher baseline OF (adjusted odds ratio, aOR, 0.93) and posttraumatic (aOR, 0.29) or idiopathic OD (aOR, 0.18) compared to postinfectious causes were significantly associated with lower odds of relevant improvements in patients with OD receiving OT. Subgroup analysis of normosmic participants receiving OT further revealed a significant association of age and baseline olfactory function with improvements of overall OF. This study demonstrated that OT was more effective than no training in patients with various causes of OD. Additi- onally, baseline olfactory performance and etiology of OD were identified as important factors associated with relevant improve- ments after OT.

Effects of Olfactory Training in Patients With Postinfectious Olfactory Dysfunction.

ObjectivesPostinfectious olfactory dysfunction (PIOD) is the most common etiology of olfactory dysfunction, and olfactory training (OT) is an accepted treatment modality for PIOD. Some studies have investigated OT in Korean patients, but they involved odorants unfamiliar to Koreans or had no control group. The aim of this study was to verify the efficacy of OT in PIOD patients, using odorants familiar to Koreans and including a control group.MethodsWe enrolled a total of 104 Korean patients with PIOD over the 3-year study period. All participants were assessed using endoscopy and an olfactory function test at the baseline assessment and 3 months after OT. The olfactory function test was performed using the Korean version of Sniffin’ stick (KVSS) II. Nasal and psychological function was evaluated using a visual analog scale and the Mini-Mental State Examination. OT was performed over a period of 3 months, using five odorants (rose, lemon, cinnamon, orange, and peach).ResultsOT improved olfactory function in approximately 40% of subjects over a period of 12 weeks compared to non-OT subjects. A comparison of changes between the initial and follow-up assessments demonstrated that the OT group had significantly better olfactory results for the total KVSS II, threshold, and identification scores than the non-OT group. The degree of olfactory improvement after OT was affected by the initial score.ConclusionThe effects of OT in patients with PIOD were demonstrated in this study. A meaningful contribution of this study is that Korean patients were tested using odors familiar to them in comparison with a control group.

The effect of olfactory training on olfactory bulb volumes in patients with idiopathic olfactory loss.

Olfactory loss impacts around 20% of the population and is associated with the reduction of pleasure from eating and drinking, sex and depression (1). Encouragingly, research findings have consistently demonstrated that olfactory training (OT) can improve olfactory function in people with olfactory loss due to various aetiologies (2). The most commonly used method for OT involves smelling four different odours (lemon, eucalyptus, rose and cloves), twice daily, for 12 weeks.

Olfactory training ball improves adherence and olfactory outcomes in post-infectious olfactory dysfunction.

In an effort to make olfactory training (OT) simpler, we designed an 'olfactory training ball' (OTB)-a baseball-size ball with four odor-containing tubes to use in OT. The study aimed to investigate the effects of OT with the OTB in comparison to classical OT with special attention to the effects of adherence to OT on olfactory outcome measures. Sixty patients with olfactory dysfunction following infections of the upper respiratory tract received OT either with classical methods-sniffing odors from jars (COT)-or the OTB for 12weeks. Patients exposed themselves to the odors for 5min twice daily. Adherence was measured with a modified version of the Morisky scale. Before and after OT, all patients underwent extensive olfactory testing using the Sniffin' Sticks test. At the end of the 12weeks of OT, TDI composite score (22.1 ± 2.8 vs. 19.9 ± 4.7, P = 0.044) and odor discrimination subtest scores (9.1 ± 1.8 vs.7.6 ± 2.5, P = 0.013) of the OTB group were significantly higher than that of the COT group. Adequate adherence to OT was significantly higher in patients receiving OTB when compared to those receiving COT (63% vs. 30%, P = 0.019). The present study shows that a novel OT device, the OTB, provides better adherence to the training process compared to COT. Moreover, findings of the current study show that better adherence to the OT process is associated with better olfactory outcomes.

Effects of olfactory training on resting-state effective connectivity in patients with posttraumatic olfactory dysfunction

The present study investigated if and how the smell training scheme affects resting‑state effective connectivity. We focused on connectivity among brain regions that participate in olfactory‑related processes, including the piriform cortex, amygdala, orbitofrontal cortex (OFC), insula, and cingulate cortex. Sixteen patients with posttraumatic olfactory dysfunctions between the ages of 18 and 36 years participated in this study. Olfactory performance of subjects was evaluated using the Sniffin' Sticks test kit and then, resting‑state functional magnetic resonance imaging (fMRI) was performed. Of the 16 participants, 8 underwent olfactory training for 16 weeks and the remaining 8 did not receive the treatment (the control group). After 16 weeks, participants in both groups underwent the same procedure (smell testing and the MRI examination). Olfactory performance scores were compared between groups using an independent samples t‑test. Spectral dynamic causal modeling was applied to resting‑state fMRI data to identify alterations in effective connectivity due to the smell training. We found that patients in the treatment group improved in the odor discrimination task and overall olfactory function as compared to the control group. Compared to the control group, patients in the treatment group had increased self‑inhibitory connectivity of the OFC and increased excitatory connectivity from the cingulate cortex to the insula. Moreover, the excitatory connectivity from the OFC to the cingulate cortex was found to be weaker following the olfactory training scheme. This study shows that a smell training scheme can cause changes in resting‑state effective connectivity parameters that can be attributed to improvements in the odor discrimination task.

Olfactory Ensheathing Cells Mediate Neuroplastic Mechanisms After Olfactory Training in Mouse Model.

Background Several studies have reported beneficial effects of olfactory training (OT) on the olfactory nervous system. However, the mechanisms underlying the regeneration of the olfactory system induced by OT are still under investigation. Objectives To determine the key mechanisms involved in the olfactory system recovery and to assess the neuroplastic effects of OT. Methods Thirty healthy female C57BL/6 mice were randomly allocated to 4 groups: control, n = 6; anosmia (no treatment), n = 8; OT, n = 8; and steroid treatment; n = 8. Except for the control group, mice were administered 3-methylindole. Anosmia was assessed using a food-finding test (FFT). The olfactory neuroepithelium was for histological examinations, gene ontology with pathway analyses, RNA, and protein studies. Results FFT was significantly reduced at 3 weeks in the OT mice versus steroids (78.27 s vs 156.83 s, P &lt; .008) and controls (78.27 s vs 13.14 s, P &lt; .003), although final outcome in the FFT was similar in these groups. Expression of olfactory and neurogenesis marker was higher in the olfactory neuroepithelium of the OT group than in the anosmia group without treatment. The mechanisms underlying olfactory regeneration might be related to early olfactory receptor stimulation, followed by neurotrophic factor stimulation of neuronal plasticity. Conclusion OT can improve olfactory function and accelerate olfactory recovery. The mechanisms underlying olfactory regeneration might be related to an initial stimulation of olfactory receptors followed by neurogenesis. Olfactory ensheathing cells might play an important role in olfactory regeneration following OT, based on the observed changes in messenger ribonucleic acid (mRNA) and protein expression, as well as the findings of the gene analysis.