Odor Threshold Test Research Articles

A perspective of randomness in a clinical test of olfactory performance

Random walks describe stochastic processes characterized by a sequence of unpredictable changes in a random variable with no correlation to past changes. This report describes the random walk component of a clinical sensory test of olfactory performance. The precise definition of this stochastic process allows the establishment of precise diagnostic cut-offs for the identification of olfactory loss. Within the Sniffin`Sticks olfactory test battery, odor discrimination (D) and odor identification (I) are assessed by four- and three-alternative forced-choice designs, respectively. Meanwhile, the odor threshold (T) test integrates a three-alternative forced-choice paradigm within a staircase paradigm with seven turning points. We explored this paradigm through computer simulations and provided a formal description. The odor threshold assessment test consists of two sequential components, the first of which sets the starting point for the second. Both parts can be characterized as biased random walks with significantly different probabilities of moving to higher (11%) or lower (89%) values. The initial odor concentration step for the first phase of the test and the length of the subsequent random walk in the second phase significantly affect the probability of randomly achieving high test scores. Changing the odor concentration from where the starting point determination for the second test part begins has raised the current cut-off for anosmia, represented as T + D + I < 16, from the 87th quantile of random test scores to the 97th quantile. Analogous findings are likely applicable to other sensory tests that use the staircase paradigm characterized as random walk.

The Effect of Methylphenidate Treatment on Olfactory Function in Children and Adolescents With ADHD

Objective: This study aimed to research whether there is an olfactory disorder in ADHD, and if so, what is the effect of methylphenidate on this condition. Method: This is a cross-sectional study aiming to evaluate olfactory threshold, identification, discrimination and threshold, discrimination, and identification (TDI) scores in 109 children and adolescents, 33 of whom have ADHD without medication, 29 with ADHD with medication and 47 control groups. Result: In the post hoc tests, the mean odor discrimination test, the mean odor identification test, and the mean TDI scores of the unmedicated ADHD group were significantly lower than those of the other two groups, and that the mean odor threshold test scores of the medicated ADHD group were significantly lower than those of the control and unmedicated groups. Conclusion: Olfactory function could be a useful tool to monitor treatment effects and may be a promising candidate as a biomarker in ADHD.

Olfactory and gustatory outcomes following endoscopic transsphenoidal hypophysectomy

ObjectiveThe aim of this study was to evaluate olfactory, gustatory, and quality-of-life outcomes in patients who underwent endonasal transsphenoidal hypophysectomy.MethodsIn this prospective study, the patients were assessed subjectively using the Malay version of sQOD-NS (short questionnaire of olfactory disorders in a negative statement) and objectively using the culturally adapted Sniffin’ Sticks smell test and taste test preoperatively and 3 months postoperatively. The Sniffin’ Sticks smell test consists of odor identification, odor discrimination, and odor threshold tests. The taste test consists of different sweet, salt, sour, and bitter concentrations.ResultsTwenty patients were enrolled in the study. The study comprises 45% female and 55% male. On average patients’ ages were 49.5 years. In this study we found a significantly reduced in odor identification score (p = 0.049) post-surgery; however, there was no statistically significant difference in odor threshold, odor discrimination, and taste. The olfactory quality of life outcome based on the Malay version of sQOD-NS (p = 0.001) was significantly reduced after surgery. There was no significant difference in the Sniffin’ Sticks smell test (p < 0.178) and taste test (p < 0.425) pre-surgery and post-surgery. The tumor’s location, either sellar or suprasellar, did not influence the smell outcome of patients postoperatively (p = 0.056).ConclusionThe study showed that the endoscopic transsphenoidal technique for pituitary surgery does not pose permanent olfactory disability.

Self-assessment of olfactory function using the “Sniffin’ Sticks”

BackgroundA precise and reliable test of the olfactory function is indispensable for the diagnosis of the olfactory disorder (OD). Despite of this, in a clinical context, often there is no place in daily routine for time-consuming procedures. This study aimed to examine if the assessment of olfactory function using the “Sniffin’ Sticks” is suitable for self-assessment.MethodsParticipants comprised 84 healthy control subjects (HC) and 37 OD patients. The “Sniffin’ Sticks” test battery consisting of odor threshold (T), discrimination (D) and identification (I) tests was used for self- and assisted assessments. To save time, we applied the 8-item wide step version of the T test and the 8-item D test, whereas the I task remained the same as the original version. The whole test included two sessions, with each session comprising a self-assessment part performed by the participants themselves, and an assisted-assessment part performed by the examiner.ResultsSniffin’ Sticks self-assessment was efficient in distinguishing between self-reported HC subjects and OD patients (p’s < 0.01), and the scores did not differ significantly from the assisted-assessment (p’s > 0.05). In the self-administered I and TDI tests, there was a moderate to excellent test–retest reliability (ICC = 0.51–0.93, p’s < 0.01), and a strong to excellent correlation with the assisted assessment (r = 0.71–0.92, p’s < 0.01). However, the self-administered T and D tests only exhibited low to moderate test–retest reliability (ICC = 0.30–0.72, p’s < 0.05) and correlations with the assisted test (r = 0.31–0.62, p’s < 0.05).ConclusionsThe Identification self-test is appropriate to be solely applied, and is therefore an easy-to-use alternative for olfactory screening in a larger segment of patients. The whole “Sniffin’ Sticks” self-test also shows good measurement properties and is therefore a suitable backup in clinical practice, but improvement is needed due to the simplified D and T self-test.

Management of post-COVID olfactory disorder: Is olfactory training effective on recovery of olfactory mucosal function?

BACKGROUND: The number of patients presenting with sudden onset and persistant anosmia and other olfactory disorders, which is a finding related to coronavirus disease has been increased considerably. In this study, we aimed to evaluate the efficacy of olfactory training in patients with persistent anosmia after Covid-19 infection.&#x0D; METHODS: Forty-six patients who applied for sudden loss of smell after Covid-19 infection and still had olfactory disorders were included in the study. Odor threshold and odor identification tests were performed on the patients before the treatment. As olfactory training, 4 scent bottles included the following groups: phenyl ethyl alcohol, eucalyptol group, citronellal group and eugenol group were given to patients and patients instructed to sniff the odors twice a day, for 5 seconds each, when they woke up in the morning and before they went to sleep and make a daily check that they applied the treatment. Patients who continued the training for 12 weeks were re-evaluated with the odor threshold test and odor identification test.&#x0D; RESULTS: The pre-training mean olfactory threshold score of the patients was 1.65±1.74, and the post-training mean olfactory threshold score was 3.89±2.73. It was observed that the olfactory threshold scores increased significantly after the olfactory training (p

Analysis of Diagnostic Value of Electrogastrography for Parkinson's Disease and its Predictive Value for the Disease Progression.

The study aimed to evaluate the diagnostic and prognostic value of indexes detected by electrogastrography in Parkinson's disease patients. One hundred twenty early Parkinson's disease patients and 120 healthy controls were recruited, and underwent electrogastrography to detect dominant frequency (DF), instability coefficient of DF (ICDF), low frequency range (LFR), high frequency range (HFR), and normal frequency range (NFR). The receiver operating characteristic (ROC) curve was drawn for the diagnostic value analysis. The motor function was scored with the Unified Parkinson's Disease Rating Scale (UPDRS). Sniffin' Sticks test was used for the olfactory evaluation, and the TDI score consisting of odor threshold (T), odor discrimination (D) and odor identification (I) tests was calculated. The preprandial ICDF of Parkinson's disease patients was significantly higher than that of the control group, and decreased slowly during the late postprandial phase. The levels of LFR%, HFR% and NFR% in Parkinson's disease patients were higher than the control group during both the preprandial and late postprandial phase, and the changes of each index before and after meals were not obvious. Preprandial ICDF value and TDI score had the ability to distinguish Parkinson's disease patients with the AUC of 0.874 and 0.859 respectively. The ICDF detected by electrogastrography has high clinical value in the early diagnosis of Parkinson's disease, and the combination of ICDF and TDI can improve the diagnostic sensitivity and specificity of a single indicator. High ICDF levels during the preprandial phase are related to the poor prognosis of Parkinson's disease patients after treatment.

Evaluation of Sense of Smell in Onychomycosis Patients Receiving Terbinafine Treatment

Aim: The most common side effects of terbinafine are gastrointestinal symptoms. Loss of taste and smell side effects are presented in a small number of case reports. We aimed to measure the effect of terbinafine on the sense of smell and the degree of change in the sense of smell in this study. Material and Methods: Odor identification test (OIT), odor threshold test (OTT), and odor discrimination test (ODT) were applied to the patients treated with terbinafine and the control group. It was applied with “Sniffin Sticks” test pens. Smell test was performed on the patient group just before the start of terbinafine treatment and at the end of 3 months of treatment. Results: There was no statistical difference between the patient and control groups in terms of age (p=0.991) and gender (p=0.811). There was no statistical difference when the initial odor tests of the patient group and the control group were compared. The OIT value of the patient group was 10.15±1.43 at the beginning and 10.10±1.15 at the end of the treatment (p=0.743). The OTT values were 6.23±1.08 at the beginning and 6.21±0.85 at the end of the treatment (p=0.811). The ODT values were 9.71±1.44 at the beginning and 9.69±1.34 at the end of the treatment (p=0.767). There was no statistical difference in the results of the tests performed at the beginning and end of the treatment. Conclusion: There was no adverse effect on the sense of smell associated with the use of systemic terbinafine treatment for 3 months.

Habitual Exposure to Trigeminal Stimuli and Its Effects on the Processing of Chemosensory Stimuli

Our objective was to compare brain responses to trigeminal and olfactory stimuli in frequent and non-frequent gum chewers in order to explore whether habitual exposure to trigeminal stimuli affects their central-nervous processing. In healthy subjects, fMRI brain scans were obtained for 20 frequent gum chewers (GC) and 20 non-frequent gum chewers (N′GC), in response to four odorous stimuli; 2 ‘trigeminal’ (peppermint and spearmint) and 2 non-trigeminal or ‘olfactory’ (cherry and strawberry). During measurements, subjects reported intensity and pleasantness ratings for all stimuli. In addition, a test for general trigeminal sensitivity test (lateralization test) and an odor threshold test was performed. Brain activations in response to individual odors were investigated for the total study population followed by group wise (GC and N′GC) analysis separately for responses to trigeminal (peppermint + spearmint) and olfactory (cherry + strawberry) odors.(1) The GC group exhibited higher trigeminal sensitivity compared to the N′GC group. (2) Olfactory odors activated bilateral insular cortex and amygdala. Apart from olfactory areas (amygdala, insular cortex), trigeminal odors also produced activations in right thalamus and right substantia nigra. (3) In the GC group, olfactory odors produced higher bilateral insular cortex activation than in N′GC group, but no such differences were observed for trigeminal odors. GC subjects appeared to be more responsive to trigeminal chemosensory stimuli. However, this did not directly translate into differences in central-nervous activations to trigeminal stimuli; instead, the use of chewing gum was associated with stronger brain activation towards olfactory stimuli.

Olfactory Performance in Youth With Full and Subthreshold Avoidant/Restrictive Food Intake Disorder

Background: Avoidant/restrictive (A/R) food intake disorder (ARFID) is characterized by restrictive eating defined by lack of interest in food, sensory sensitivity, and/or fear of aversive consequences of eating resulting in a failure to meet adequate nutritional and/or energy needs. The complex psychopathology that differentiates ARFID from other eating disorders highlights the need to explore the role of sensory systems in disease etiology. Olfaction has an important role in eating behavior. Specifically, olfactory dysfunction is associated with decreased food intake and appetite. Olfactory performance and associated clinical characteristics have yet to be examined in individuals with ARFID. We hypothesized that higher levels of PYY, which signals satiety, would be associated with poorer olfactory performance; whereas greater food fussiness and A/R eating severity would be associated with stronger olfactory performance. Methods: We evaluated a cross-sectional sample of children and adolescents with full and subthreshold ARFID (n=82, 46.2% female, mean age 15.8±3.8). We measured olfactory performance with the Sniffin’ Sticks test (Burghardt®, Wedel, Germany) which captures odor discrimination, odor identification, and odor threshold. Higher scores on all three indices represent stronger olfactory performance. We also measured fasting serum PYY; severity of A/R eating on the Pica, ARFID and Rumination Disorder Interview (PARDI); and food fussiness as a measure of food-related sensory sensitivity on the Adult Eating Behavior Questionnaire. Statistical analyses included T-test and spearman’s correlations. Results: Greater fasting serum PYY levels were associated with significantly poorer performance on the odor threshold test (r=-0.4, p=0.003). Greater severity of A/R eating (r=-0.3 p=0.008) and food fussiness (r=-0.2, p=0.03) were both associated with significantly poorer performance on the odor discrimination test. Conclusions: As predicted, we found that higher levels of PYY were associated with poorer olfactory performance in youth with full and subthreshold ARFID. However, contrary to hypotheses, we found that greater food fussiness and severity of A/R eating were associated with poorer olfactory performance. Future research should investigate whether high levels of PYY and poor olfactory performance are causes, consequences, or correlates of A/R eating.

Objective evaluation of odor loss in COVID-19 and other suspected cases.

IntroductionCOVID-19 is a pandemic disease known with one of the symptoms is sudden onset anosmia. This symptom sometimes may be the only sign of the disease, therefore it must be research widely.ObjectiveWe aim to evaluate odor dysfunction in COVID-19 patients objectively and safely without any risk of transmitting the disease.MethodsThe odor threshold test was performed on 105 patients hospitalized at the XXXX Training and Research Hospital on the COVID-19 pandemic service before any treatment began. Odor threshold was tested using a modification of the Connecticut Chemosensory Clinical Research Center olfactory function test. COVID-19 signs and symptoms, PCR test results, thorax computed tomography (CT) findings, and length of hospital stay were recorded. Odor tests were scored between 0–8, 0–1 anosmia, 2–3 severely hyposmia, 4 moderate hyposmia, 5 mild hyposmia, 6 and above normosmia.ResultsForty-one (39%) of the 105 patients were diagnosed with COVID-19 after the PCR results. Patients with an odor threshold score < 5 were classified as “Smell-Impaired Group”, patients with an odor threshold score ≥ 5 were placed in “Smell Intact Group”. The incidence of female patients in smell-impaired group was significantly higher (p ˂ 0.05). The proportion of patients who were PCR-positive for COVID-19 in smell-impaired group was significantly higher (p ˂ 0.05) than in smell intact group. Among patients with an odor threshold score from 0 to 1 (anosmic; n = 15), 12 (80%) demonstrated PCR positivity (p < 0.0001).ConclusionAnosmia can be predictive for coronavirus disease. Odor threshold test can be helpful for diagnosis.

Psychophysical evaluation of chemosensory functions 5weeks after olfactory loss due to COVID-19: a prospective cohort study on 72 patients.

PurposeTo evaluate the evolution of chemosensation via extended psychophysical testing in patients who suffered from sudden chemosensory loss due to coronavirus disease 2019 (COVID-19). Additionally, this study sought to determine whether odor threshold testing provided additional information on olfactory loss due to COVID-19 compared to the more common odor identification testing.MethodsProspective cohort study of patients with sudden chemosensory loss since February 2020 and confirmed COVID-19 infection via RT-PCR or serology testing. Olfactory function was tested extensively using the “Sniffin Sticks” test battery. In addition, we screened gustatory perception and nasal cooling sensations using psychophysical tests.ResultsSeventy-two patients completed the study. After a mean of 37 days, 37% of patients showed olfactory dysfunction, 7% were dysgeusic, and 48% showed signs of low sensitivity for cooling sensation. A longer duration of anosmia before smell improvement was correlated with lower olfactory function at 5 weeks. Odor threshold detection was more affected by COVID-19 compared to odor identification.ConclusionFive weeks after developing sudden chemosensory loss due to COVID-19, a high proportion of patients were dysosmic and showed signs of low nasal cooling sensitivity, whereas most of them had normal taste function. SARS-CoV-2 affected mainly odor thresholds, possibly suggesting that the major cause of loss of smell lies at the level of the olfactory neuroepithelium, rather than in the central nervous system.

The effect of tobacco- and electronic cigarettes use on the olfactory function in humans

Electronic cigarettes are a recent development in tobacco harm reduction. They are marketed as a “healthier alternative” to conventional cigarettes but their health impact is unknown. Therefore, the aim of this study was to investigate the odor perception of smokers and vapers (e-cigarette consumers) in comparison to non-smokers. For the study 181 study participants aged 18 to 46 years were selected and divided into three groups including the control group (n = 70 non-smokers; 40 women, 30 men), as well as two investigated groups consisted of smokers (n = 66; 32 women, 34 men) and vapers (n = 45; 18 women, 27 men). The individuals were evaluated by applying the “Sniffin‘ Sticks” odor threshold (T), discrimination (D), and identification (I) test. To express the overall results a composite threshold-discrimination-identification (TDI) score was calculated. The results of the threshold test showed a significant difference (p ≤ 0.05) between non-smokers and smokers, as well as smokers and vapers. The data of odor discrimination- and odor identification, as well as the TDI-score revealed a significant difference (p ≤ 0.05) between all three evaluated groups. Furthermore, according to the Pearson test, there was a significant correlation (p ≤ 0.05) between the “pack-years” and odor threshold and the TDI-score. However, the correlation between the “pack-years” and the results of the odor discrimination and identification was not statistically significant (p > 0.05). Besides, the duration of vaping (in years) and amount of consumed liquid (ml) did not correlate (p > 0.05) with the odor threshold, discrimination, identification as well as the TDI-score. Finally, it can be stated that the non-smoker group exhibited the best performance in the conducted olfactory tests, closely followed by the vapers. In contrast, the consumption of cigarettes had a negative impact on the olfactory perception of smokers.

Faster olfactory adaptation in patients with olfactory deficits: an analysis of results from odor threshold testing.

Patients with olfactory deficits often report rapid and lasting olfactory adaptation compared to the time when they had normal olfactory function. However, this phenomenon receives little scientific attention. This retrospective study aimed to compare the patterns of olfactory adaptation in normosmic controls and patients with olfactory impairment by analyzing the trajectory of turning points in odor threshold tests based on the staircase technique. 4120 subjects (1684 hyposmia, 1742 anosmia and 694 normosmic controls) were included in this study. Their odor threshold, odor discrimination and odor identification ability were assessed using the Sniffin’ Sticks. We analyzed the trajectory of turning points in the odor threshold test. Current results suggested that patients with hyposmia needed significantly more trials to reach the final threshold scores than controls and anosmic group, and controls needed more trials than anosmic group. The difference between the first turning point and final threshold scores in the anosmic group was significantly larger than in the hyposmia group and in controls. People with poor olfaction seem to adapt faster to olfactory stimuli. The trajectory of turning points in odor threshold test may serve as an indicator of olfactory adaptation and function of olfactory receptors. Olfactory adaptation may provide a new tool in the assessment of subtle olfactory loss.

Reversible obstruction of the olfactory cleft: impact on olfactory perception and nasal patency.

BackgroundTemporary disruption of sensory input can be studied relatively easily for vision or hearing by covering the eyes or ears. In contrast, closing the nostrils affects not only the sense of smell, but also the ability to breathe through the nose and humidify and warm inhaled air. We hypothesized that filling the olfactory cleft (OC) with dissolvable nasal dressing (foam) would temporarily block olfaction while respecting nasal airflow.MethodsIn 30 healthy volunteers, the OC was unilaterally obstructed in a back‐to‐front fashion. Orthonasal and retronasal olfactory function were tested before and after foam application. Ratings of odors and subjective nasal patency (SNP) were collected. Peak nasal inspiratory flow (PNIF) was used to measure nasal patency.ResultsFoam was safely applied in every case using minimal instruments. No complications were reported. Orthonasal and retronasal test results decreased significantly in overall participants (all p < 0.0008). Indicating temporary anosmia, 3 subjects reached the lowest possible score for odor‐threshold testing, with corresponding drops in retronasal test scores. PNIF values before and after foam application were not significantly different (p = 0.11). SNP ratings decreased slightly, but not significantly (p = 0.052). Odor‐intensity ratings dropped significantly (all p < 0.05).ConclusionThe OC can be safely obstructed with dissolvable nasal dressing, resulting in a decrease in odor‐intensity and orthonasal and retronasal olfactory function test scores. This procedure may serve as a hyposmia model that maintains normal nasal airflow.

Smoking cessation improves olfactory functions.

The aim of this study was to investigate changes in olfactory function after smoking cessation. We conducted a cross-sectional study involving 28 volunteers who were admitted to the smoking cessation section of our hospital. Olfactory tests were performed immediately before smoking cessation and 45 days after smoking cessation. The duration of smoking and the number of cigarettes smoked per day were noted. The mean duration of smoking was 25.5 ± 12 years, and the participants smoked 21.6 ± 6.6 cigarettes per day. There was a significant improvement in odor discrimination, odor identification, and TDI scores (i.e., the total score of odor threshold, odor discrimination, and odor identification tests) 45 days after smoking cessation (P = .003, P = .002, and P < .001, respectively). Furthermore, a statistically significant negative correlation was found between the duration of cigarette smoking and the Sniffin' Sticks olfactory tests performed after smoking cessation, namely odor discrimination, odor identification, and TDI (P = .008, P = .002, P = .001, respectively). A significant improvement was observed in odor discrimination, odor identification, and TDI scores after smoking cessation. However, this improvement was inversely associated with the duration of smoking, indicating that a longer duration of smoking may result in an insufficient improvement after smoking cessation. 4 Laryngoscope, 130:E35-E38, 2020.

Olfactory functioning in adults with Tourette syndrome.

Tourette syndrome is a chronic tic disorder characterized by motor and vocal tics. Comorbidities such as attention deficit hyperactivity disorder and obsessive compulsive disorder can be found. The overlap between neuroanatomical regions and neurotransmitter systems in the olfactory system and the pathophysiology of Tourette syndrome let us hypothesize altered olfactory performance in Tourette syndrome. The main objective of this study was to systematically assess olfactory functioning in subjects with Tourette syndrome and to compare it to healthy controls. We assessed 28 adults with Tourette syndrome (age 33.1±9.4 years, disease duration 23.7±9.7 years) and 28 healthy controls (age 32.9±9.0 years) matched in regard to age, sex, education and smoking habits. The “Sniffin Sticks” test battery was applied to assess odor threshold, discrimination, and identification. Additionally, the combined score of the odor threshold test, the odor discrimination test and the odor identification test of the “Sniffin Sticks” test battery was calculated. Although it was not the primary aim of this study, we assessed whether tics and comorbidity could contribute to olfactory alterations in adults with Tourette syndrome. Therefore, clinical scores were used to assess severity of tics and co-morbidity such as attention deficit hyperactivity disorder, obsessive compulsive disorder, anxiety and depression in subjects with Tourette syndrome. Pathology of the nasal cavities was excluded with rhinoendoscopy. Independent sample t-tests were applied to compare performance in olfactory tests. In the case of statistically significant differences (critical p-value: 0.05), multiple linear regression analysis was carried out to explore whether tic severity, social impairment, co-morbidity or medical treatment had an impact on the differences found. Descriptive values are reported as mean ± standard deviation. Tourette syndrome subjects showed lower combined scores (Tourette syndrome subjects 31.9 ± 5.1 versus healthy controls 35.0 ± 3.1; p = 0.007), odor identification scores (Tourette syndrome subjects 12.4 ± 2.0 versus healthy controls 13.7 ± 1.4; p = 0.008) and odor discrimination scores (Tourette syndrome subjects 12.1 ± 2.1 versus healthy controls 13.2 ± 1.6; p = 0.041) in comparison to healthy subjects, while there was no difference in odor threshold (Tourette syndrome subjects 7.3 ± 2.7 versus healthy controls 8.1 ± 2.2; p = 0.22). Seven out of 28 Tourette syndrome subjects (25%) scored in the range of the age- and sex-dependent combined score for hyposmia, while two of 28 healthy controls (7%) had a similar low combined score. None of the participants were found to have functional anosmia. Multiple linear regression analyses suggest that social impairment may a predictor for low combined score and odor identification score in Tourette syndrome subjects (p = 0.003). Compared to healthy controls, altered olfaction in adults with Tourette syndrome was found in this study. Normal odor threshold level but lower scores at tasks involving supra-threshold odor concentrations point towards a central-nervous alteration in the processing of olfactory information in Tourette syndrome.

The confounding effect of background odors on olfactory sensitivity testing

BackgroundHuman olfactory sensitivity is known to vary significantly across subjects. Furthermore, environmental factors such as background noise and odor are known to affect target odor threshold scores but have not yet been fully delineated. We aimed to determine whether congruent and non-congruent background odor impaired target odor threshold scores. New methodWe performed odor threshold testing in 103 normosmic adults, using phenylethylalcohol (PEA) or linalool as target odors, under three conditions: (a) congruent target and background odors (e.g., PEA in the test and PEA in the background), (b) non-congruent target and background odors (e.g. PEA in the test and Linalool in the background) and (c) no background odor. Background odor was applied to the investigator’s glove and testing was performed in an otherwise odorless room. ResultsWe found that congruent background odors significantly impaired target odor threshold scores. Non-congruent background odors also impaired target odor threshold, but significantly more so with PEA as target and Linalool as background odor. The best threshold scores were obtained with no background odor. Comparison with Existing Method(s).At present, many testing environments may be contaminated with ambient background odors. We have shown that this may negatively affect odor threshold scores, particularly where background and target odors are congruent. ConclusionsWe suggest that investigators performing odor threshold testing do so in well ventilated, odor free environments.

Improvement of Olfactory Function With High Frequency Non-invasive Auricular Electrostimulation in Healthy Humans.

In past literature on animal models, invasive vagal nerve stimulation using high frequencies has shown to be effective at modulating the activity of the olfactory bulb (OB). Recent advances in invasive vagal nerve stimulation in humans, despite previous findings in animal models, used low frequency stimulation and found no effect on the olfactory functioning. The present article aimed to test potential effects of non-invasive, high and low frequency vagal nerve stimulation in humans, with supplementary exploration of the orbitofrontal cortex using near-infrared spectroscopy (NIRS). Healthy, male adult participants (n = 18) performed two olfactory tests [odor threshold test (OTT) and supra-threshold test (STT)] before and after receiving high-, low frequency vagal nerve stimulation and placebo (no stimulation). Participant's olfactory functioning was monitored using NIRS, and assessed with two behavioral olfactory tests. NIRS data of separate stimulation parameters were statistically analyzed using repeated-measures ANOVA across different stages. Data from olfactory tests were analyzed using paired parametric and non-parametric statistical tests. Only high frequency, non-invasive vagal nerve stimulation was able to positively modulate the performance of the healthy participants in the STT (p = 0.021, Wilcoxon sign-ranked test), with significant differences in NIRS (p = 0.014, post-hoc with Bonferroni correction) recordings of the right hemispheric, orbitofrontal cortex. The results from the current article implore further exploration of the neurocircuitry involved under vagal nerve stimulation and the effects of non-invasive, high frequency, vagal nerve stimulation toward olfactory dysfunction which showcase in Parkinson's and Alzheimer's Diseases. Despite the sufficient effect size (moderate effect, correlation coefficient (r): 0.39 for the STT) of the current study, future research should replicate the current findings with a larger cohort.

Validation of olfactory threshold testing methods.

In patients with chemosensory complaints, a head-to-head comparison of unilateral olfaction threshold testing with the Phenyl Ethyl Alcohol Smell Threshold Test (PEA) and the OLFACT-RL Odor Threshold Test (OLFACT-RL) was undertaken. The charts of 23 consecutive patients presenting with chemosensory complaints seen at the Smell and Taste Treatment and Research Foundation were reviewed and information extracted per Institutional Review Board guidelines. All patients had undergone olfactory testing with the PEA test and the OLFACT-RL test in accordance with their published administration manuals. Using Spearman correlation coefficients to measure the statistical correlation between tests, we found evidence of a correlation between PEA and OLFACT-RL values on the left side only, overall (r = 0.49, p = 0.0184); in those who had hyposmia and did not have anosmia (r = 0.42, p = 0.0668); in those who did not have burning mouth syndrome (r = 0.46, p = 0.0304); and in those who did not have dysosmia (r = 0.47, p = 0.0553). There is no evidence of a correlation on the right side. The correlation for the left nostril suggests that these tests may be interchangeable. However, lack of correlation with the right nostril requires further investigation.

Heightened Olfactory Sensitivity in Young Females with Recent-Onset Anorexia Nervosa and Recovered Individuals.

IntroductionOlfaction may be related to food restriction and weight loss. However, reports regarding olfactory function in individuals with anorexia nervosa (AN) have been inconclusive.ObjectiveCharacterize olfactory sensitivity and identification in female adolescents and young adults with first-episode AN and young females recovered from AN.MethodsWe used the Sniffin’ Sticks Odor Threshold Test and Odor Identification Test to assess 43 participants with first-episode AN, 27 recovered participants, and 39 control participants. Participants completed the Importance of Olfaction questionnaire, the Beck Youth Inventory and the Eating Disorder Inventory. We also conducted a psychiatric diagnostic interview and the Autism Diagnostic Observation Schedule with participants.ResultsBoth clinical groups showed heightened olfactory sensitivity. After excluding participants with depression, participants with first-episode AN identified more odors than recovered participants.ConclusionHeightened olfactory sensitivity in AN may be independent of clinical status, whereas only individuals with current AN and without depression show more accurate odor identification.