'Sniffin' sticks': olfactory performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold

Odor identification dysfunction in late-life depression with suicidal ideation

BACKGROUND

Suicide is more prevalent among older adults compared to younger individuals. Late-life depression (LLD) poses the highest risk for suicide. However, early recognition of suicidal ideation is challenging. Dysfunction in odor identification (OI), a characteristic of LLD, may hold potential for early identification of suicidal ideation. This study aims to compare OI between LLD patients with suicidal ideation (LLD-S) and LLD patients without suicidal ideation (LLD-NS), and examine its relationship with cognitive function.

METHODS

A total of 262 LLD-NS patients, 63 LLD-S patients, and 316 healthy normal older adults (HOAs) underwent OI testing, standardized clinical interviews, and comprehensive neuropsychological assessments.

RESULTS

(1) LLD-S patients exhibited lower OI scores and poorer cognitive performance (including global cognition, information processing speed, memory, language, executive function, and visuospatial ability) compared to LLD-NS patients and HOAs. (2) There were interactive effects between suicidal ideation and OI dysfunction, leading to lower scores in information processing speed and visuospatial ability. (3) OI dysfunction mediated the differences in cognition between the LLD-NS and LLD-S groups.

LIMITATIONS

The present study was a cross-sectional design.

CONCLUSIONS

LLD-S patients had worse odor identification than LLD-NS patients and HOAs, suggesting that OI testing could be a valuable approach for identifying suicidal ideation in LLD and screening for suicide risk. The presence of both OI impairment and suicidal ideation was associated with poorer cognitive performance in LLD.

How well can young adults and children discriminate between odors?

It is widely believed that people can distinguish between many odors although there is limited empirical evidence. Odor discrimination tasks are employed much less often than other measures of olfaction, but, interestingly, performance is typically ~ 75% correct. This less-than-perfect performance is rarely highlighted, although it suggests that people may not be as good at discriminating odors as is commonly believed. Odor discrimination is understudied in children, and although available evidence suggests that it improves with age, children perform better when the task is simpler. In the present study, we explored odor discrimination in children and young adults with a relatively simple same-different task using common and uncommon odors. We found that children perform as well as young adults, but that overall performance was less than perfect and depended on the odors to be discriminated. We found evidence that ability to discriminate between odors improves as the difference in pleasantness of the odors increases. In a second experiment, we tested this directly by exploring whether odors that differ in pleasantness and edibility, two dimensions that appear to be important in olfactory perception, are easier to discriminate than odors that are the same on those dimensions. We found further evidence that odors that differ in pleasantness are easier to discriminate.

A novel olfactory sorting task

BACKGROUND

This study aimed to develop a simple self-administered screening tool for odor memory, which allowed users to self-test their olfactory function repeatedly even at home.

METHODS

One hundred and ten participants were recruited (30 men, age = 50.1 ± 9.9 years; 80 women, age = 47.1 ± 11.5 years); half of them were heathy volunteers, the other half were patients with olfactory dysfunction. Fifty-one healthy participants volunteered for a retest within an interval of a maximum of 14 days. Olfactory function was assessed using the extended Sniffin' Sticks test (SST) comprising tests for odor threshold, identification, and discrimination. All participants received the Novel Olfactory Sorting Task (NOST) which is based on the sorting of 12 matching pairs of odors involving olfactory and cognitive functions. After that, all participants rated questions related to their test performance and the practicability of the test.

RESULTS

Consistent with the previous literature, significant effects of age were found. Results showed an acceptable test-retest reliability and a satisfactory validity of the NOST. The NOST score not only had positive correlations with SST, but also was capable of differentiating severe hyposmia/anosmia from normosmia by the score of 5.5 (sensitivity of 76.2%, specificity of 77.6%).

CONCLUSION

The present study showed the good reliability, validity, and possible clinical usefulness of the NOST. As a self-performed screening test, it can be comprehended and conducted easily, which may provide a quick and simple approach to obtaining a global estimation of olfactory and cognitive functions.

Efficacy of forskolin as a promising therapy for chronic olfactory dysfunction post COVID-19

PURPOSE

Olfactory dysfunction is increasingly common among COVID-19 patients, impacting their well-being. Reports have demonstrated decreased levels of cyclic adenosine monophosphate and cyclic guanosine monophosphate among patients with chronic olfactory dysfunction. A prospective randomized clinical trial was developed to demonstrate the efficacy of an oral forskolin regimen treatment, an adenylyl cyclase activator that raises intracellular levels of cyclic adenosine monophosphate, for the treatment of olfactory dysfunction following COVID-19, compared to placebo regimen.

METHODS

The study enrolled 285 participants with persistent olfactory dysfunction post COVID-19 infection, randomly assigning them to receive either placebo capsules (n = 120) or oral forskolin capsules (n = 165). Follow-up was conducted to track progress, with 18 participants from the placebo group and 12 from the forskolin group lost during this period. Olfactory function was assessed using the "Sniffin' Sticks" test, measuring threshold, discrimination and identification scores before and after treatment.

RESULTS

Subjects administered forskolin capsules demonstrated a significant enhancement in their composite TDI (threshold, discrimination and identification) score, suggesting a notable amelioration in olfactory functionality. Moreover, the discrimination and identification scores notably improved within the forskolin group. Conversely, no significant alterations were observed in the threshold scores.

CONCLUSION

This study suggests that forskolin can contribute potentially to improve chronic olfactory dysfunction post COVID-19.

TRIAL REGISTRATION

DFM-IRB00012367-23-10-001.

Intranasal Trigeminal Function in Aging Adults

BACKGROUND

Intranasal trigeminal function is important in detecting environmental stimuli. The impact of age-associated chemosensory dysfunction upon taste and olfaction is well described, but an understanding of trigeminal loss (chemesthesis) is lacking.

OBJECTIVE

The goal of this study was to characterize trigeminal function in a cohort of older adults and explore potential impacts.

METHODS

Twenty-eight participants over 50 years of age were recruited from the community as part of an aging cohort study. This nested cohort completed chemosensory questionnaires, patient-reported outcome measures (PROMs), and psychophysical testing for taste (taste strips), olfaction (Sniffin' Sticks), and trigeminal function (eucalyptol lateralization). Data were analyzed for associations between trigeminal function, olfactory, and taste psychophysical performance, patient-reported metrics, and demographic risk factors.

RESULTS

Patient-reported trigeminal impairment is less severe than other chemosensory loss, with mean visual analog scores (VAS, rated 0-100 from least to most severe) for smell (32.9 ± 34.2), taste (20.6 ± 28.4), and trigeminal sensation (9.5 ± 12.8). Despite low VAS scores, psychophysical trigeminal dysfunction was present in 10 (35.7%) subjects. Psychophysical olfactory and taste dysfunction were present in 16 (57.1%) and eight (28.6%) participants respectively. Hypercholesterolemia was associated with psychophysical trigeminal dysfunction (mean lateralization performance in hypercholesterolemia 57.7% ± 17.1 vs. 74.1% ± 10.4, p = .008).

CONCLUSION

Intranasal trigeminal impairment is present in nearly one-third of aging adults when assessed by psychophysical methods but is under-recognized. Hyperlipidemia may be associated with trigeminal impairment. Future inquiries should better characterize these findings in larger and prospective cohorts.

Treatment of COVID-19 Associated Olfactory Dysfunction: A Systematic Review

PURPOSE OF REVIEW

COVID -19 associated olfactory dysfunction is widespread, yet effective treatment strategies remain unclear. This article aims to provide a comprehensive systematic review of therapeutic approaches and offers evidence-based recommendations for their clinical application.

RECENT FINDINGS

A living Cochrane review, with rigorous inclusion criteria, has so far included 2 studies with a low certainty of evidence. In this systematic review we list clinical data of 36 randomised controlled trials (RCTs) and non-randomised studies published between Jan 1, 2020 and Nov 19, 2023 regarding treatment options for COVID-19 associated olfactory dysfunction. Nine treatment groups were analysed, including olfactory training, local and systemic corticosteroids, platelet-rich plasma (PRP), calcium chelators, vitamin supplements including palmitoylethanolamide with luteolin, insulin, gabapentin and cerebrolysin. Primary objective was the effect of the studied treatments on the delta olfactory function score (OFS) for objective/psychophysical testing. Treatments such as PRP and calcium chelators demonstrated significant improvements on OFS, whereas olfactory training and corticosteroids did not show notable efficacy for COVID-19 associated olfactory dysfunction.

Impact of Weight Loss on Olfaction in Patients Undergoing Bariatric Surgery

PURPOSE

Olfaction plays a vital role in regulating nutrition, avoiding potentially dangerous situations, and modulating behavior along with interpersonal relationships. Many common disorders can have a negative impact on olfaction; one of these is obesity. Bariatric surgery induces weight loss, and current evidence suggests that it can cause improvement in olfaction. However, more information is needed regarding this topic.

MATERIALS AND METHODS

One hundred eighty-five patients who underwent bariatric surgery and 184 age- and gender-matched control group who did not undergo any surgery have completed a questionnaire including items from the validated Self-Reported Mini Olfactory Questionnaire.

RESULTS

Final analysis was based on 369 patients. There was a statistically significant difference between patients before and after surgery (p < 0.05). However, there was a statistically significant difference between people who underwent surgery with < 50% excess body weight loss and the control group but none with those > 50% excess body weight loss. No significant differences were found when comparing people with and without chronic illnesses, head and neck surgery, anti-allergy drug use, and COVID-19. Before surgery, there were statistically significant differences between patients with allergic rhinitis and polyps and those without, but no significant differences were observed after surgery.

CONCLUSION

Patients had significantly improved olfactory scores post-surgery compared to before surgery. Patients who had > 50% excess body weight loss after surgery showed olfactory function as good as the general population represented by the control group. However, those with < 50% excess body weight loss had significantly worse olfactory scores compared to the general population.

Development and validation of the four-item Concise Aging adults Smell Test to screen for olfactory dysfunction in older adults

BACKGROUND

Olfactory dysfunction (OD) in the elderly is common and associated with numerous comorbidities, yet often underrecognized. This study sought to develop an instrument for widespread screening of this condition.

METHODS

Demographic factors, comorbidities, and olfactory-related questions were examined in a focus group (N = 20) and development cohort (N = 190). The 4-item Concise Aging adults Smell Test (4-CAST) screening instrument was then developed to predict OD on Sniffin Sticks testing. An independent validation cohort (N = 147) was then examined to confirm ability of the 4-CAST to predict OD on Smell Identification Test 40 (SIT40).

RESULTS

The most important variables for predicting olfactory loss in older subjects were age, type II diabetes status, Visual Analog Scale (VAS) of overall rating of smell, and VAS of impact of smell upon safety. In the development cohort, the 4-CAST model yielded predictive probability (area under the curve) of 0.805 (p < 0.001) for predicting the bottom 25th percentile on Sniffin Sticks. Results were similar in the validation cohort, as the 4-CAST accurately classified 83.8% subjects (area under the curve [AUC] 0.789, p < 0.001) in the bottom 25th percentile of SIT40 testing. The 4-CAST was able to accurately classify 89.4% of subjects with anosmia.

CONCLUSION

The 4-CAST is a quick screening instrument for predicting OD in older adults and has similar performance characteristics in independent populations using the two most common validated olfactory tests. Given the high prevalence of unrecognized olfactory loss in this population, this can be a useful tool for practitioners to determine which subjects may benefit from more extensive olfactory testing.

Differential Nasal Recolonization and Microbial Profiles in Chronic Rhinosinusitis With Nasal Polyps Patients After Endoscopic Sinus Surgery or Dupilumab Treatment: A Prospective Observational Study

INTRODUCTION

The role of microbial profiles in Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) pathogenesis is increasingly recognised, with microbial imbalances perpetuating inflammation. We performed this study to associate the different nasal microbiological profile changes with the response to surgical or monoclonal treatment.

METHODS

This prospective observational study evaluated changes in the nasal microbial profiles of 44 patients (22 dupilumab, 22 surgery) over 6 months. Clinical assessments were performed at baseline and follow-ups, including Sino-Nasal Outcome Test-22 (SNOT-22) scores and Sniffin Sticks-Identification (SS-I) olfactory testing. Microbial profiling of nasal swabs was carried out by microbial culture and subsequent molecular identification by Polymerase chain reaction (PCR) and sequencing.

RESULTS

Baseline characteristics of 44 patients (22 dupilumab, 22 surgery) enrolled in this study were similar between groups. In the dupilumab group, Staphylococcus epidermidis prevalence rose from 37.03% to 59.25%, while Pseudomonas aeruginosa was eradicated. Moreover, dupilumab stabilised Staphylococcus aureus at 63.64%, while its prevalence increased in the surgery group (from 22.72% to 50%). When bacterial groups were associated with clinical scores, P. aeruginosa carriers had worse SNOT-22 (21.00 ± 1.41) and SS-I (5.50 ± 0.71) scores. Instead, S. epidermidis-colonised patients exhibited significantly lower mean SNOT-22 (15.39 ± 8.54) and greater SS-I scores (8.39 ± 3.77). The best outcomes were found in the subgroup of S. epidermidis carriers undergoing the dupilumab treatment.

CONCLUSION

The two treatments modulated the microbial profiles differently, and, most importantly, clinical responses might depend on the association between treatment and the dominant bacterial species colonising the nasal cavity. Further investigation into microbial-restorative strategies could enhance outcomes for better treatment of CRS.

Sniffing out a solution: How emotional body odors can improve mindfulness therapy for social anxiety

BACKGROUND

Human body odors (BOs) serve as an effective means of social communication, with individuals exposed to emotional BOs experiencing a partial replication of the sender's affective state. This phenomenon may be particularly relevant in conditions where social interactions are impaired, such as social anxiety. Our study aimed to investigate if emotional human BOs could augment the benefits of mindfulness-based interventions.

METHODS

We enrolled 48 women with social anxiety symptoms and assigned them to groups exposed to happiness BO, fear BO, or clean air. Participants engaged in mindfulness practice over two consecutive days, which included breathing, meditation, and relaxation exercises. During these interventions, the odor specific to each group was presented. Affective symptoms were assessed at the beginning and end of each day, with heart rate variability (HRV) and skin conductance level (SCL) recorded during the intervention.

RESULTS

Self-reported anxiety level revealed a significant reduction in anxiety on the second day for both happiness and fear conditions, but not for the clean air group. However, on a physiological level, fear BO exposure compared to clean air led to decreased HRV, indicating that fear BO may induce a less physiological relaxed state. No significant differences were observed in SCL between odor conditions.

CONCLUSIONS

These findings suggest that exposure to BOs triggers the perception of a "social presence", improving the ecological validity of a psychological treatment. If replicated and expanded, these findings could pave the way for using BOs as catalysts in existing therapies.

Association between olfactory function and metabolic syndrome in bipolar disorder patients: a cross-sectional study

BACKGROUND

Olfactory function is closely related to mood and the endocrine system. However, the role of olfactory function in bipolar disorder combined with metabolic syndrome remains unclear. The purpose of this study was to explore the associations among olfactory function, tumor necrosis factor alpha (TNF-α), and metabolic syndrome and its components in patients with bipolar disorder.

METHODS

Ninety-six bipolar disorder patients were divided into two groups with and without metabolic syndrome. We also included 46 healthy controls. Olfactory function was assessed using the Sniffin' Sticks test. Blood samples were collected to measure metabolic indicators and serum TNF-α levels.

RESULTS

Significant differences in olfactory function were found among the three groups. Compared with the healthy controls, the bipolar disorder without metabolic syndrome group showed poorer olfactory identification ability (P < 0.001) and the bipolar disorder with metabolic syndrome group showed impaired olfactory sensitivity (P = 0.003) and olfactory identification (P < 0.001). Moreover, the bipolar disorder with metabolic syndrome group had poorer olfactory identification ability than the bipolar disorder without metabolic syndrome group (P = 0.015). Both bipolar disorder groups showed lower TNF-α levels than healthy controls. However, there was no significant difference between the two patient groups. Correlation analysis showed that, in the bipolar disorder with metabolic syndrome group, olfactory identification was negatively correlated with systolic blood pressure (r = - 0.424, P = 0.031), and serum TNF-α level was negatively correlated with body mass index (BMI; r = - 0.398, P = 0.049), triglyceride (r = - 0.503, P = 0.010), total cholesterol (r = - 0.491, P = 0.013), low-density lipoprotein-cholesterol (r = - 0.491, P = 0.013), and high-density lipoprotein-cholesterol (r = - 0.454, P = 0.023).

CONCLUSIONS

The olfactory identification ability of patients with bipolar disorder is worse than that of healthy controls, and the occurrence of metabolic syndrome will further aggravate the olfactory identification impairment of those patients. Furthermore, there may be a stronger link between serum TNF-α level and multiple metabolic indicators in bipolar disorder patients with metabolic syndrome than in bipolar disorder patients without metabolic syndrome.

Cribriform Plate Foramina Count in Patients With Acquired and Congenital Anosmia

BACKGROUND

Cribriform foramina provide the openings for olfactory nerve fibers to cross from the nasal cavity to the olfactory bulb. Disruption of the olfactory nerve fibers is known to affect olfactory function, but little is known about the potential effects on the number of cribriform foramina in congenital anosmia.

OBJECTIVE

This pilot study aimed to investigate whether there was a reduction in foramina in patients with acquired and congenital anosmia (including both Kallmann syndrome and isolated congenital anosmia) compared to controls with normal olfactory function.

METHODS

Paranasal CT image stacks were analyzed from 20 patients with congenital anosmia (n = 6), acquired anosmia (n = 6), or normal olfactory function (n = 8). Cribriform foramina were counted by three observers from the slice revealing the crista galli and the ethmoidal slits. The two closest values for each subject were analyzed in comparison across the three groups using one-way analysis of variance.

RESULTS

Patients with congenital, but not acquired, anosmia had significantly fewer cribriform foramina (x̄ ± SE = 10.17 ± 1.23) compared to healthy, normosmic controls (x̄ ± SE = 19.88 ± 2.01). There was no significant difference in foramina count between congenital and acquired anosmics (x̄ ± SE = 15.83 ± 3.47).

CONCLUSION

In this pilot study, a reduced number of cribriform foramina was found in individuals with congenital anosmia. Examination of cribriform foramina could be helpful in counseling patients with olfactory loss. Further investigation in larger studies with additional cohorts is warranted.

Behavioral separation of liking and wanting in response to olfactory and visual food cues

In real-world settings, food rewards are processed in parallel across several sensory modalities, but paradigms that compare contributions of different modalities are lacking. While odor perception in particular is frequently implicated in appetite regulation, the mechanisms by which food odors differentially evoke experiences of wanting and liking remain poorly understood. This study addressed this gap by dissociating liking from wanting responses for olfactory stimuli, and establishing commonalities and differences relative to the visual modality. In two separate experiments, participants (n1 = 37, n2 = 43) rated content-matched batteries of odors and pictures, respectively, for their ability to elicit pleasure (liking) and desire to eat (wanting). A third experiment (n3 = 39) utilized a combined olfactory-visual paradigm to test the separation of these dimensions in a multisensory context. Our results show that participants differentiated clearly and reliably between liking and wanting for both odors and pictures, as demonstrated by a high difference score between the two in non-food (high liking, low wanting), but not in food (both high) or disgusting stimuli (both low), and high within-session retest reliability. Higher variability for olfactory relative to visual assessments was observed and likely reflects well-established difficulties with odor object identification. Taken together, our study demonstrates that olfactory stimuli can be used in experimental settings to evoke separable experiences of liking and wanting for food and non-food stimuli. Manipulating these components independently across sensory modalities in experimental studies could generate novel insights into how olfactory and visual cues differentially contribute to anticipatory and consummatory food reward processing, in healthy and disordered eating.

Multi-channel portable odor delivery device for self-administered and rapid smell testing

To improve our understanding of the perception of odors, researchers are often required to undertake experimental procedures with users exposed to multiple odors in a variety of settings, including to diagnose smell loss in clinics and care homes. Existing smell tests are typically administered using multiple sniffing pens, manually presented to patients by a highly specialized nurse using a time-consuming and complex testing paradigm. Automated odor delivery devices, such as olfactometer systems, exist but are expensive, bulky and typically lab based, making them difficult to use for on the ground odor delivery. Here we have developed a portable, affordable, odor delivery device that can deliver 24 odors through individual channels with high temporal precision and without cross-contamination. The device allows for the rapid, flexible sequencing of odors via digital control using a mobile application and has been experimentally validated in the lab, as well as tested on patients. The design provides several advantages for investigating olfactory perception and offers the possibility that users can one day self-administer smell tests in a range of settings, including at home, allowing smell healthcare services to evolve and become part of a routine practice and self-care culture.

Qualitative and Quantitative Sex-Related Differences in the Perception of Single Molecules from Coffee Headspace

One of the still-debated topics regarding the olfactory function concerns the presence or absence of sex-related differences in individuals. In this study, we checked for a relationship between the olfactory function of females and males and their ability to perceive single molecules, and researched how this can influence the intensity with which the complex odor formed by a set of single molecules is perceived. First, females and males were classified as normosmic or hyposmic based on the TDI olfactory score obtained using the Sniffin' Sticks test. Subsequently, the headspace of roasted coffee beans, as a complex olfactory stimulus, was broken down into single molecules by means of a chromatographic column; these were simultaneously conveyed to a mass spectrometer (for their subsequent classification) and to the human nose, which acts as a chemical sensor by means of an olfactometer port. The results obtained with this gas chromatography-olfactometry approach show both qualitative and quantitative differences between females and males, with females performing better than males. In addition, the odor intensity reported by females when sniffing pen #10, containing coffee aroma, is significantly higher than that reported by males. In conclusion, these data highlight that the human ability to perceive both single compounds and complex odors is strongly conditioned, not only by the olfactory function of individuals, but also by their sex.

Orthonasal and retronasal olfactory function in patients with chronic rhinosinusitis without nasal polyps undergoing endoscopic sinonasal surgery

BACKGROUND

Olfactory dysfunction (OD) is a key symptom of chronic rhinosinusitis (CRS). Although extensively studied in CRS with nasal polyps (CRSwNP), OD in CRS without nasal polyps (CRSsNP) remains under-researched. This study aims to assess the prevalence of OD and its evolution in surgically naïve patients with CRSsNP undergoing endoscopic sinus surgery (ESS).

METHODS

This prospective study included 97 participants with CRSsNP (mean age, 46.5 years; 70.1% men) and 97 healthy controls (mean age, 46.5 years; 70.1% men). Participants underwent psychophysical evaluations of orthonasal (using the Sniffin' Sticks test) and retronasal olfaction (using powdered aromas) at enrolment and 6 months post-ESS.

RESULTS

Out of 97 patients, 81 (83.5%) completed all assessments. At enrolment, 23 (28.4%) CRSsNP patients had OD based on composite threshold, discrimination, identification scores, compared with 7 (8.6%) controls (absolute % difference, 19.8% [95% CI, 8.2-31.4]). Retronasal olfactory function was also significantly worse in CRSsNP patients. Six months post-ESS, 30 patients (37.0%) experienced a clinically significant improvement in olfactory, whereas nonsignificant changes were observed in retronasal olfactory score, and 3.7% of patients experienced a deterioration of the olfactory function.

CONCLUSIONS

In conclusion, although 37% of patients experienced a clinically significant improvement in their sense of smell following ESS, the overall prevalence of OD in this surgically naive population appears relatively low, especially when compared to that observed in patients with CRSwNP. Therefore, ESS may offer some benefits for enhancing orthonasal olfactory function, but the extent of these improvements appears to be limited.

Odor lateralization test is insensitive to small degrees of intranasal trigeminal activation

INTRODUCTION

Odors with prominent trigeminal compounds are more easily localized than purely olfactory ones. However, it is still unclear whether adding a small amount of a trigeminal compound to an olfactory odor significantly improves lateralization performance.

METHODS

We included 81 healthy adults aged 25.4 ± 4.8 years to complete odor lateralization tasks using 12 odors: two "olfactory", two "trigeminal" odors, and eight odor mixtures at two low concentrations of "trigeminal" odors (4%, 8%). This task utilized a "Squeezer" delivering odor or air to either nostril, and participants indicated which nostril received the odor. Evaluations also included olfactory function, odor intensity ratings, and individual olfactory importance.

RESULTS

Degrees of trigeminal compounds significantly affected lateralization performance (F = 82.32, p < 0.001), with 100% irritants showing higher performance than 0%, 4%, and 8% irritants (p's < 0.001), while no significant differences were found between odors with 0%, 4%, and 8% irritants (p's > 0.05). Chi-square tests confirmed higher percentages of above-chance lateralization with 100% irritants than with 0%, 4%, and 8% irritants (χ2 = 30.89 to 47.33, p's < 0.001).

CONCLUSIONS

Adding a small amount of a trigeminal compound to a selective olfactory odor does not significantly improve lateralization performance. Trigeminal lateralization likely follows an "accumulative" pattern rather than an "all or none" rule. With only 20 trials, the task may lack sensitivity to detect low levels of trigeminal irritation in selective olfactory odors, though it does not rule out trigeminal activation. The odor lateralization task can screen for odors with prominent trigeminal compounds by comparing group-level performance with that of purely olfactory odors. Future studies should use more ideal stimuli (e.g., PEA for olfactory, CO2 for trigeminal) to test the replicability of the results.

Taste and smell are associated with dietary intake, eating behavior, nutritional status, and health-related quality of life in children with cancer

BACKGROUND & AIMS

Smell and taste changes are frequently reported bothersome treatment symptoms during treatment for childhood cancer and assumed to influence outcomes such as food intake. Since nutritional status of children with cancer is already vulnerable, any detrimental effects on food intake should be prevented. Therefore, understanding the exact relationship between chemosensory changes and dietary intake, eating behavior, and other domains such as health-related quality of life (HRQoL), is important for improving outcomes.

METHODS

In this longitudinal study, we followed 87 childhood cancer patients treated for hematological, solid, or brain malignancies. Smell (odor threshold and odor identification) and taste function (total taste score) were objectively investigated using commercial Sniffin' Sticks and Taste Strips respectively, and by self-report. Dietary intake was measured using a 3-day food dairy. For nutritional status, BMI expressed as standard deviation scores was derived from medical records. Eating behavior and HRQoL were assessed by the Behavioral Pediatrics Feeding Assessment Scale (BPFAS) and PedsQL 4.0 Generic Core Scales, respectively. Measurements were taken approximately 6 weeks (T0), 3 months (T1), 6 months after starting chemotherapy (T2), and 3 months after termination of chemotherapy or maintenance phase for children with acute lymphoblastic leukemia (ALL) (T3). Dietary intake, eating behavior, nutritional status, and HRQoL were modelled over time using mixed model analysis. Associations between smell and taste (objective and self-report), as well as patient characteries were studied.

RESULTS

Energy intake significantly increased during the study period, with a higher age, BMI, and total taste scores associated to this increase. Boys had higher energy intake compared to girls. Eating behavior scores significantly declined, indicating less eating problems. Age, pre-diagnosis eating behavior, self-reported smell changes, and tube feeding were associated to eating behavior. BMI significantly increased, with a higher BMI at diagnosis to be related to a higher BMI during the study period. A lower BMI was found in children receiving tube feeding and self-reported taste changes. HRQoL improved during the study period, with lower HRQoL in children receiving tube feeding and self-reported taste changes.

CONCLUSION

Both objective and subjective measures of taste and smell influence dietary intake, eating behavior, nutritional status, and HRQoL. Individual dietary advice and coping strategies are warranted to prevent detrimental effects of chemosensory changes on food intake and clinical outcomes in children with cancer.

Association of Exercise with Better Olfactory Performance and Higher Functional Connectivity Between the Olfactory Cortex and the Prefrontal Cortex: A Resting-State Functional Near-Infrared Spectroscopy Study

Background: Olfactory deterioration is suggested to be a predictor of some neurodegenerative diseases. Recent studies indicate that physical exercise has a positive relationship with olfactory performance, and a subregion in the prefrontal cortex (PFC) may play an important role in olfactory processing. The PFC is not only related to olfactory function but it also engages in complex functions such as cognition and emotional processing. Methodology: Our study compared the functional connectivity between the olfactory cortex and the PFC in healthy individuals who exercised regularly and healthy persons who did not. Those who exercised more than three times/week for at least 30 min each time were considered the exercise group, and those who did not meet this exercise criteria were considered the nonexercise group. We also assessed their odor threshold. Participants were aged 55 years or older, and the two groups were balanced for age, sex, body mass index, and educational level. Results: We found that compared with individuals who did not exercise, exercisers had a significantly lower threshold for detecting odors. In addition, the olfactory cortex had stronger connectivity with the PFC in exercisers than in nonexercisers. More specifically, when the PFC was grouped into three subregions, namely, the ventrolateral prefrontal cortex (VLPFC), dorsolateral prefrontal cortex (DLPFC), and frontopolar cortex (FPA), Pearson correlation analysis revealed stronger connectivity between the VLPFC and the orbitofrontal cortex (OFC), between the OFC and the FPA, and between the left and right OFC hemispheres in the exercisers. In addition, Granger causality indicated higher directional connectivity from the DLPFC to the OFC in exercisers than in nonexercisers. Conclusion: Our findings indicated that the exercise group not only had better olfactory performance but also had stronger functional connectivity between the olfactory cortex and the PFC than nonexercise group.

Tuberculum sellae meningiomas: surgical outcomes in 65 patients, review of the literature and proposal for an anatomical and radiological classification

Tuberculum sellae meningiomas (TSM) are challenging tumors due to their proximity to vital neurovascular structures. We propose a new classification system based on anatomical and radiological parameters. All patients treated for TSM, between January 2003 and December 2016, have been retrospectively reviewed. A systematic research was performed in PubMed database to review all studies comparing the performance of transcranial (TCA) and transphenoidal (ETSA) approaches. Overall, 65 patients were included in the surgical series. Gross total removal (GTR) was achieved in 55 patients (85%) and near total resection in 10 (15%). 54 patients (83%) showed a stability or an improvement of visual functions and 11 (17%) worsened. Postoperative complications were observed in seven patients (11%): CSF leak in one patient (1.5%); diabetes insipidus in two (3%); hypopituitarism in two (3%) third cranial nerve paresis and subdural empyema in one (1.5%). For the literature review, data about 10,833 patients (TCA N.=9159; ETSA N.=1674) were recorded; GTR was achieved in 84.1% (range 68-92%) of TCA and in 79.1% (range 60-92%) of ETSA; visual improvement (VI) occurred in 59.3% of TCA (range 25-84%) and in 79.3% of ETSA (range 46-100%); visual deterioration (VD) was registered in 12.7% of TCA (0-24%) and in 4.1% of ETSA (range 0-17%); a CSF-leak was observed in 3.8% of TCA (range 0-8%) while in ETSA in 18.6% of patients (range 0-62%); vascular injuries was reported in 4% (range 0-15%) of TCA and in 1.5% (range 0-5%) of ETSA. In conclusion, TSMs represent a unique category of midline tumors. The proposed classification system provides an intuitive and reproducible method in the choice of the most suitable approach.

Treatments for Olfactory Dysfunction in COVID-19: A Systematic Review

Introduction  Olfactory dysfunction (OD) has emerged as a notable symptom among coronavirus disease 2019 (COVID-19) patients, with its prevalence varying among different populations. Recognizing the need to provide therapeutic solutions for these individuals, the present study seeks to comprehensively review the current evidence on potential underlying mechanisms and treatment modalities to manage OD in COVID-19 patients. Objective  To review the recent evidence on treatments for OD in COVID-19. From the beginning of the study until August 2nd, 2023, we conducted a systematic search on four electronic databases, PubMed, Scopus, Embase, and Web of Science, to find relevant publications. Data Synthesis  In the present study, 37 articles were selected for data extraction and included in the final review. The total number of patients was of 3,560 (2,098 female and 1,462 male subjects). The predominant disorders reported were hyposmia, anosmia, and parosmia. In most of the studies, the pre and postintervention assessments were the same, except for one study, in which the pre-intervention assessment of the disorder was through the SST, Sniffin' Sticks Test (SST), and the post-intervention assessment was through the Visual Analog Scale (VAS) and the 22-item Sinonasal Outcome Test (SNOT-22). The findings suggest olfactory training (OT), ivermectin, palmitoylethanolamide, luteolin, and systemic corticosteroids, in combination with topical corticosteroids, are potential therapies for COVID-19 patients with olfactory impairment. Conclusion  Although the review suggested several medications for OD treatment, further research must delve into the specific impact of OT, a non-pharmacological modality, regarding the mitigation of OD. By continuing to investigate and refine these therapeutic approaches, we can better support COVID-19 patients and improve their quality of life while navigating the challenges posed by OD.

The efficacy of olfactory training in improving olfactory function: a meta-analysis

PURPOSE

Study the efficacy of olfactory training in smell recovery.

METHODS

An extensive search was performed through different databases in order to find articles analyzing the efficacy of olfactory training as a treatment for olfactory dysfunction. Methodological quality of primary studies within the final sample was assessed following PRISMA guidelines. Standardized mean differences in pre-post olfactory training groups, and also in experimental-control and pre-follow up if possible, were computed by Hedges' g effect size statistic. Each effect size was weighted by its inverse variance.

RESULTS

Final sample was composed of 36 articles (45 pre-post effect sizes). Contrasts were performed separately for odor identification, odor discrimination, odor threshold and general olfactory function. Moderate to large and heterogeneous effect was obtained for olfactory function (g = 0.755, k = 45, SE = 0.093, CI 95% = [0.572, 0.937]), different moderators had a significant effects, such as, training duration, age and anosmia diagnosis.

CONCLUSION

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

A Rose by Another Name? Odor Misnaming is Associated with Linguistic Properties

Naming common odors is a surprisingly difficult task: Odors are frequently misnamed. Little is known about the linguistic properties of odor misnamings. We test whether odor misnamings of old adults carry information about olfactory perception and its connection to lexical-semantic processing. We analyze the olfactory-semantic content of odor source naming failures in a large sample of older adults in Sweden (n = 2479; age 58-100 years). We investigate whether linguistic factors and semantic proximity to the target odor name predict how odors are misnamed, and how these factors relate to overall odor identification performance. We also explore the primary semantic dimensions along which misnamings are distributed. We find that odor misnamings consist of surprisingly many vague and unspecific terms, such as category names (e.g., fruit) or abstract or evaluative terms (e.g., sweet). Odor misnamings are often strongly associated with the correct name, capturing properties such as its category or other abstract features. People are also biased toward misnaming odors with high-frequency terms that are associated with olfaction or gustation. Linguistic properties of odor misnamings and their semantic proximity to the target odor name predict odor identification performance, suggesting that linguistic processing facilitates odor identification. Further, odor misnamings constitute an olfactory-semantic space that is similar to the olfactory vocabulary of English. This space is primarily differentiated along pleasantness, edibility, and concreteness dimensions. Odor naming failures thus contain plenty of information about semantic odor knowledge.

Neuroimaging evaluations of olfactory, gustatory, and neurological deficits in patients with long-term sequelae of COVID-19

The World Health Organization indicated that around 36 million of patients in the European Region showed long COVID associated with olfactory and gustatory deficits. The precise mechanism underlying long COVID clinical manifestations is still debated. The aim of this study was to evaluate potential correlations between odor threshold, odor discrimination, odor identification, and the activation of specific brain areas in patients after COVID-19. Sixty subjects, 27 patients (15 women and 12 men) with long COVID and a mean age of 40.6 ± 13.4 years, were compared to 33 age-matched healthy controls (20 women and 13 men) with a mean age of 40.5 ± 9.8 years. Our data showed that patients with long COVID symptoms exhibited a significant decrease in odor threshold, odor discrimination, odor identification, and their sum TDI score compared to age-matched healthy controls. In addition, our results indicated significant correlations between odor discrimination and the increased activation in the right hemisphere, in the frontal pole, and in the superior frontal gyrus. This study indicated that the resting-state fMRI in combination with the objective evaluation of olfactory and gustatory function may be useful for the evaluation of patients with long COVID associated with anosmia and hyposmia.

Comparative imaging study of patients with persistent olfactory dysfunction due to mild COVID-19 using structural and functional MRI

INTRODUCTION

Persistent post-COVID olfactory dysfunction continues to be studied due to the controversy in its pathophysiology and neuroimaging.

MATERIALS AND METHODS

The patients had confirmed mild COVID-19 infection with olfactory dysfunction of more than one month of evolution and they were compared to controls with normal olfaction, assessed using the Sniffin' Sticks Olfactory Test and underwent brain, magnetic resonance imaging (MRI) of the olfactory bulb and olfactory function.

RESULTS

A total of 8 patients and 2 controls participated. The average age of the patients was 34.5 years (SD 8.5), and that of the controls was 28.5 (SD 2.1). The average score in the patients' olfactory test was 7.9 points (SD 2.2). In brain and olfactory bulb MRI tests, no morphological differences were found. When evaluated by functional MRI, none of the patients activated the entorhinal area in comparison to the controls, who did show activation at this level. Activation of secondary olfactory areas in cases and controls were as follows: orbitofrontal (25% vs 100%), basal ganglia (25% vs 50%) and insula (38% vs 0%) respectively.

CONCLUSIONS

There were no observed morphological changes in the brain MRI. Unlike the controls, none of the patients activated the entorhinal cortex in the olfactory functional MRI.

A Pilot Study of the Computerized Brief Smell Identification Test

Objectives: A self-administered Computerized Brief Smell Identification Test (cB-SIT) was developed recently to perform the olfactory identification test under computer control. The aim of this study was to evaluate the clinical applicability of the cB-SIT as compared with the traditional Brief Smell Identification Test (B-SIT). Methods: Sixty healthy volunteers with self-reported normal olfactory function, 30 hyposmic patients, and 30 anosmic patients were enrolled from June 2023 to May 2024. All enrolled participants received both B-SIT and cB-SIT in a random order to measure their odor identification ability. Thirty healthy volunteers took the second B-SIT and cB-SIT at least one week later. Results: The score was significantly different in both B-SIT and cB-SIT among healthy volunteers, hyposmic, and anosmic patients. The correct answer rate was significantly different in 10 items of the B-SIT and in 7 items of the cB-SIT among the three groups, but the post hoc test showed significant differences in correct answer rates between healthy volunteers and hyposmic patients in 7 items of both the B-SIT and cB-SIT. Test-retest results showed the score of the second B-SIT test was significantly higher than that of the first test, but the scores of the two tests of the cB-SIT were not significantly different. In the B-SIT, the lemon odorant had a higher correct answer rate in the second test than in the first test, but in the cB-SIT, the correct answer rate was not significantly different between the first and second tests in all 12 items. Conclusions: Our findings demonstrate that the cB-SIT was similar to the B-SIT and can be administered in the diagnosis of patients with olfactory dysfunction.

Olfaction and thyroid hormones in patients with subjective cognitive decline, non-amnestic and amnestic mild cognitive impairment

BACKGROUND

Thyroid hormones may affect olfaction in different stages of cognitive impairment: subjective cognitive decline (SCD), non-amnestic (naMCI) and amnestic mild cognitive impairment (aMCI). Additionally, biometric parameters, depression, and neuropsychological performance are considered as possible influencing factors.

DESIGN AND PATIENTS

A retrospective single-center data analysis was conducted during the observation period 2001-2023, with n = 495 (52.3% female) SCD, naMCI and aMCI subjects, aged ≥50 years, at the General Hospital of Vienna.

MEASUREMENTS

The criterion olfactory function was objectively measured by Sniffin' Sticks© odor identification and subjectively through the Assessment of Self-Reported Olfactory Functioning test. Serum thyroid hormone levels, mainly thyroid-stimulating hormone, as well as T3, T4, fT3, and fT4, were used to assess thyroid function. Statistical analyses using IBM SPSS® 29.0.0 covered adjusted multiple linear regression models with hierarchical blocks to predict olfactory performance considering β‑weights.

RESULTS

Of the study participants, 4.2% had hypothyroidism and 2.4% had hyperthyroidism. The majority exhibited normal thyroid function. One third (33.5%; 95% confidence interval, CI 29.4-37.0%) were hyposmic. The results indicate no substantial association between thyroid and olfactory functions. Increasing age (β = 0.20), lower performance in the Neuropsychological Test Battery Vienna (NTBV) dimensions verbal memory (β = -0.33) and attention (β = -0.12) appear to be risk factors for lower olfaction. A discrepancy between subjective and objective olfaction was found.

CONCLUSION

Thyroid and olfactory functions had no substantial relationship. Higher fT4 correlated weakly with lower odor identification. Increasing age and decreased performance in two out of six NTBV dimensions are relevant prognostic factors for olfactory dysfunction.

Olfactory performance and odor liking are negatively associated with food neophobia in children aged between 3 and 9 years

BACKGROUND

Child food neophobia, i.e., rejection or avoidance of novel foods at a young age, is a prevalent nutrition problem that affects the quality of children's diet and impedes the development of healthy food preferences. Sensory sensitivity can relate to the degree of food neophobia, but previous studies rarely focused on the olfactory component of this problem in children.

OBJECTIVE

We aimed to thoroughly examine the relationship between various aspects of olfactory sensitivity and food neophobia in children.

METHODS

246 children aged between three and nine years took part in a food neophobia assessment as well as in a comprehensive, psychophysical olfactory testing.

RESULTS

We found that certain smell perception aspects such as lower odor liking, poorer odor identification ability as well as lower sensitivity to an unknown non-food odor all significantly predicted higher food neophobia in children. Among individual characteristics of either a child or a caregiver, only the child's age significantly and positively predicted food neophobia. The exploratory model looking into the role of family environment factors predicting self-reported food neophobia in children revealed that food neophobia was associated with lower control given to a child in this child's feeding process, as well as with a more frequent use of food as a reward in feeding.

CONCLUSIONS

We suggest that suppressed olfactory perception and performance can play a unique role in child nutritional difficulties. The study inspires further considerations of olfaction-engaging interventions to counteract food-neophobia in children.

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.

Acetyl-DL-leucine in two individuals with REM sleep behavior disorder improves symptoms, reverses loss of striatal dopamine-transporter binding and stabilizes pathological metabolic brain pattern-case reports

Isolated REM Sleep Behavior Disorder (iRBD) is considered a prodrome of Parkinson's disease (PD). We investigate whether the potentially disease-modifying compound acetyl-DL-leucine (ADLL; 5 g/d) has an effect on prodromal PD progression in 2 iRBD-patients. Outcome parameters are RBD-severity sum-score (RBD-SS-3), dopamine-transporter single-photon emission computerized tomography (DAT-SPECT) and metabolic "Parkinson-Disease-related-Pattern (PDRP)"-z-score in 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). After 3 weeks ADLL-treatment, the RBD-SS-3 drops markedly in both patients and remains reduced for >18 months of ADLL-treatment. In patient 1 (female), the DAT-SPECT putaminal binding ratio (PBR) decreases in the 5 years pretreatment from normal (1.88) to pathological (1.22) and the patient's FDG-PET-PDRP-z-score rises from 1.72 to 3.28 (pathological). After 22 months of ADLL-treatment, the DAT-SPECT-PBR increases to 1.67 and the FDG-PET-PDRP-z-score stabilizes at 3.18. Similar results are seen in patient 2 (male): his DAT-SPECT-PBR rises from a pretreatment value of 1.42 to 1.72 (close to normal) and the FDG-PET-PDRP-z-score decreases from 1.02 to 0.30 after 18 months of ADLL-treatment. These results support exploration of whether ADLL may have disease-modifying properties in prodromal PD.

Circulating calprotectin as a potential biomarker of persistent olfactory dysfunctions in Post-COVID-19 patients

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.

DISCUSSION AND 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.

The digital scent device 20: an automated, self-administered odor identification test

PURPOSE

Assessing olfactory function is highly significant in clinical practice, particularly in the context of the recent COVID-19 pandemic. Recent approaches in this field emphasize the importance of reducing the time and cost devoted to olfactory testing procedures. Hence, the aim of the present study was to examine the reliability and basic characteristics of Digital Scent Device 20 (DSD-20), an innovative olfactory test consisting of 20 "universal odors", in a European population.

METHODS

A total of 88 participants (mean age = 45.1, SD = 20.3) volunteered for the study. The sample consisted of 37 normosmic controls and 51 dysosmic patients.

RESULTS

The correlation between DSD-20 and the total score in Sniffin' Sticks was high (TDI; R = .80, p < .001), and the test correlated with the individual components of the Sniffin' Sticks test. Furthermore, the correlation coefficient between DSD-20 test and retest was very high (R = .88, p < .001), which was additionally confirmed by a Bland-Altman plot. Essential characteristics of the DSD-20 are its simplicity in self-administration, speed of application, portability, and the fact that it can be reused.

CONCLUSION

Overall, the present study confirms previous notions on DSD-20 by demonstrating its high reliability and usefulness in separating patients with hyposmia/anosmia and normosmic controls.

Beyond Distracted Eating: Cognitive Distraction Downregulates Odor Pleasantness and Interacts with Weight Status

Considering the widespread issue of distracted eating, our study investigates how cognitive distraction influences the sensory perception of food-related odors among individuals with varying weight statuses. We conducted an exploratory, randomized, and cross-sectional experimental study, using the Tetris game to simulate real-life cognitive distraction, incorporating two distraction levels (low and high) and presenting five distinct odors. A total of 59 participants, categorized into a lean (n = 30) and overweight/obese group (n = 29) based on their body mass index (BMI), received odor stimuli while playing Tetris at low and high difficulty, corresponding to low and high distraction levels, respectively. Participants subsequently rated odor intensity and pleasantness under the two cognitive distraction conditions. Respiratory movements were monitored to ensure accurate olfactory stimulation. Our findings revealed no significant difference in odor intensity ratings across distraction levels (p = 0.903). However, there was a significant reduction in odor pleasantness under high cognitive distraction (p = 0.007), more pronounced in lean participants compared to those with an overweight status (p = 0.035). Additionally, an interaction between gender and cognitive distraction effects was observed in odor pleasantness perception. The differential effects of distraction across weight-status groups and genders are discussed in the context of hedonic motivation and compensatory mechanisms. This study sheds light onto the sensory mechanisms underlying distracted eating and could inform more personalized strategies for promoting healthier eating habits in a world dominated by distractions.

Emotion perception through the nose: how olfactory emotional cues modulate the perception of neutral facial expressions in affective disorders

Humans can decode emotional states from the body odors of the conspecifics and this type of emotional communication is particularly relevant in conditions in which social interactions are impaired, as in depression and social anxiety. The present study aimed to explore how body odors collected in happiness and fearful conditions modulate the subjective ratings, the psychophysiological response and the neural processing of neutral faces in individuals with depressive symptoms, social anxiety symptoms, and healthy controls (N = 22 per group). To this aim, electrocardiogram (ECG) and HD-EEG were recorded continuously. Heart Rate Variability (HRV) was extracted from the ECG as a measure of vagal tone, event-related potentials (ERPs) and event-related spectral perturbations (ERPSs) were extracted from the EEG. The results revealed that the HRV increased during the fear and happiness body odors conditions compared to clean air, but no group differences emerged. For ERPs data, repeated measure ANOVA did not show any significant effects. However, the ERPSs analyses revealed a late increase in delta power and a reduced beta power both at an early and a late stage of stimulus processing in response to the neutral faces presented with the emotional body odors, regardless of the presence of depressive or social anxiety symptoms. The current research offers new insights, demonstrating that emotional chemosignals serve as potent environmental cues. This represents a substantial advancement in comprehending the impact of emotional chemosignals in both individuals with and without affective disorders.

Influence of Single Nucleotide Polymorphisms on CRS Outcomes: A Preliminary Observational Study

OBJECTIVE(S)

To conduct a preliminary investigation into the relationship between specific SNP variants, type II inflammation, and the effectiveness of dupilumab therapy and surgery in patients with CRS.

METHODS

In this prospective study, 48 subjects were enrolled, comprising 32 CRS patients and 16 healthy controls. The CRS patients were subjected to either dupilumab therapy or endoscopic surgery according to EPOS guidelines. SNP variants were identified using the TaqMan SNP genotyping technique. The identified SNP profiles were compared between the control group and CRS patients, and their potential influence on treatment outcomes was evaluated. Treatment responses were assessed based on symptom scores, such as SS-I, SNOT-22, disease progression using the NPS findings, and SNP profiles at a 6-month follow-up. The primary measures included the Nasal Polyp Score, Smell Identification Test (SIT) score, and SNOT-22 outcomes.

RESULTS

Dupilumab therapy and surgery significantly decreased NPS, with the last showing superior results. However, dupilumab therapy resulted in a significantly improved SIT score. Significant differences were observed in SNP profiles, particularly with rs1800629 (TNFA), rs2856838 (IL1a), rs17561 (IL1a), and rs1805011 (IL4R). In particular, the expression of rs2856838 and rs1805011 variants in the dupilumab group was associated with significantly better SIT and SNOT-22 outcomes than non-expressors. Also, the surgery group patients expressing the rs2856838 variant reported significant improvements in SNOT-22 scores.

CONCLUSION

These preliminary findings suggest that SNP genotypes may guide personalized treatment strategies for CRS. Further larger prospective studies are required to confirm these initial observations.

LEVEL OF EVIDENCE

2 Laryngoscope, 2024.

Congenital absence of touch does not preclude normal cognitive and socioemotional development

Attachment theory holds that development of normal affective and social behavior requires physical contact between infant and caregiver. The elevation of touch to paramount importance has gone unchallenged because, prior to the present study, no individual with a congenital lack of somatosensation has been reported, much less studied for psychosocial development. Here we describe Kim, who since birth, has been unable to perceive touch, temperature changes, or pain on the body surface. Despite her inability to sense physical contact, Kim has above-average intelligence. She functions normally in social situations with a variety of people, recognizing emotions in herself and others and demonstrating appropriate affect. Kim experiences anxiety that appears grounded in realistic fears and uncertainties particular to her somatic insensitivity, thus serving as adaptive vigilance in reaction to an abnormal sensorium. Her normal socioemotional development, evident from an early age, likely resulted from Kim being able to appreciate her parents' loving care through gaze, movement, and hearing. In sum, Kim upends the idea of touch as critical to developing a sense of self, secure attachment, and family bonds.

AROMHA Brain Health Test: A Remote Olfactory Assessment as a Screen for Cognitive Impairment

Cost-effective, noninvasive screening methods for preclinical Alzheimer's disease (AD) and other neurocognitive disorders remain an unmet need. The olfactory neural circuits develop AD pathological changes prior to symptom onset. To probe these vulnerable circuits, we developed the digital remote AROMHA Brain Health Test (ABHT), an at-home odor identification, discrimination, memory, and intensity assessment. The ABHT was self-administered among cognitively normal (CN) English and Spanish speakers (n=127), participants with subjective cognitive complaints (SCC; n=34), and mild cognitive impairment (MCI; n=19). Self-administered tests took place remotely at home under unobserved (among interested CN participants) and observed modalities (CN, SCC, and MCI), as well as in-person with a research assistant present (CN, SCC, and MCI). Olfactory performance was similar across observed and unobserved remote self-administration and between English and Spanish speakers. Odor memory, identification, and discrimination scores decreased with age, and olfactory identification and discrimination were lower in the MCI group compared to CN and SCC groups, independent of age, sex, and education. The ABHT revealed age-related olfactory decline, and discriminated CN older adults from those with cognitive impairment. Replication of our results in other populations would support the use of the ABHT to identify and monitor individuals at risk for developing dementia.

Hot topic: Mapping of the human intranasal mucosal thermal sensitivity: A clinical study on thermal threshold and trigeminal receptors

INTRODUCTION

The olfactory and trigeminal system are closely interlinked. Existing literature has primarily focused on characterizing trigeminal stimulation through mechanical and chemical stimulation, neglecting thermal stimulation thus far. The present study aimed to characterize the intranasal sensitivity to heat and the expression of trigeminal receptors (transient receptor potential channels, TRP).

METHODS

A total of 20 healthy participants (aged 21-27 years, 11 women) were screened for olfactory function and trigeminal sensitivity using several tests. Under endoscopic control, a thermal stimulator was placed in 7 intranasal locations: anterior septum, lateral vestibulum, interior nose tip, lower turbinate, middle septum, middle turbinate, and olfactory cleft to determine the thermal threshold. Nasal swabs were obtained in 3 different locations (anterior septum, middle turbinate, olfactory cleft) to analyze the expression of trigeminal receptors TRP: TRPV1, TRPV3, TRPA1, TRPM8.

RESULTS

The thermal threshold differed between locations (p = 0.018), with a trend for a higher threshold at the anterior septum (p = 0.092). There were no differences in quantitative receptor expression (p = 0.46) at the different sites. The highest overall receptor RNA expression was detected for TRPV1 over all sites (p<0.001). The expression of TRPV3 was highest at the anterior septum compared to the middle turbinate or the olfactory cleft. The thermal sensitivity correlated with olfactory sensitivity and results from tests were related to trigeminal function like intensity ratings of ammonium, a questionnaire regarding trigeminal function, nasal patency, and CO2 thresholds. However, no correlation was found between receptor expression and psychophysical measures of trigeminal function.

DISCUSSION

This study provided the first insights about intranasal thermal sensitivity and suggested the presence of topographical differences in thermal thresholds. There was no correlation between thermal sensitivity and trigeminal mRNA receptor expression. However, thermal sensitivity was found to be associated with psychophysical measures of trigeminal and olfactory function.

Olfactory perceptual fingerprints of people with olfactory dysfunction and healthy controls

Objectives

An olfactory perceptual fingerprint (OPF) defines one's olfactory perception using perceptual descriptor ratings (such as odor pleasantness, intensity) for a set of odors. OPFs have been shown to distinguish patients with COVID-related olfactory dysfunction (OD) and healthy controls with 86% accuracy. However, all participants rated the same odorants. With the aim to evaluate whether the OPFs are indeed odorant independent, previously published dataset by Lötsch et al. was reanalyzed. Furthermore, this independent dataset was used to check whether the OPFs separate patients with OD due to various causes from controls.

Methods

The study included 104 controls and 42 patients, who were randomized into four odor sets with 10 odorants each. Odorants were presented using a computer-controlled olfactometer and evaluated on scales from 1 (not at all) to 5 (very) using perceptual descriptors pleasant, intensive, familiar, edible, irritating, cold/warm, and painful.

Results

Permutational multivariate analysis of variance showed that the odor set did not have a significant effect on the OPFs, confirming that the OPFs are indeed odorant independent. On the other hand, both diagnosis and age affected the OPFs (p < .001) and explained around 11% and 5% of the variance of the OPFs, respectively. Furthermore, a supervised machine learning method, random forest classifier, showed that OPF can distinguish patients and controls with 80% accuracy.

Conclusion

OPFs are odorant independent. Patients perceived odors as less familiar, less intense, and less edible than controls. Other perceptual descriptors were much less important for the separation of patients and controls.

Level of evidence

3.

Detecting Misfolded α-Synuclein in Blood Years before the Diagnosis of Parkinson's Disease

BACKGROUND

Identifying individuals with Parkinson's disease (PD) already in the prodromal phase of the disease has become a priority objective for opening a window for early disease-modifying therapies.

OBJECTIVE

The aim was to evaluate a blood-based α-synuclein seed amplification assay (α-syn SAA) as a novel biomarker for diagnosing PD in the prodromal phase.

METHODS

In the TREND study (University of Tuebingen) biennial blood samples of n = 1201 individuals with/without increased risk for PD were taken prospectively over 4 to 10 years. We retrospectively analyzed blood samples of 12 participants later diagnosed with PD during the study to detect and amplify pathological α-syn conformers derived from neuronal extracellular vesicles using (1) immunoblot analyses with an antibody against these conformers and (2) an α-syn-SAA. Additionally, blood samples of n = 13 healthy individuals from the TREND cohort and n = 20 individuals with isolated rapid eye movement sleep behavior disorder (iRBD) from the University Hospital Cologne were analyzed.

RESULTS

All individuals with PD showed positive immunoblots and a positive α-syn SAA at the time of diagnosis. Moreover, all PD patients showed a positive α-syn SAA 1 to 10 years before clinical diagnosis. In the iRBD cohort, 30% showed a positive α-syn SAA. All healthy controls had a negative SAA.

CONCLUSIONS

We here demonstrate the possibility to detect and amplify pathological α-syn conformers in peripheral blood up to 10 years before the clinical diagnosis of PD in individuals with and without iRBD. The findings of this study indicate that this blood-based α-syn SAA assay has the potential to serve as a diagnostic biomarker for prodromal PD. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Pronounced Olfactory Habituation with Age

OBJECTIVES

Olfactory habituation is a transient decrease in olfactory sensitivity caused by prolonged odor exposure, aiding in the discernment of new olfactory stimuli against the background. We explored the impact of subclinical olfactory impairment on odor habituation using age as a proxy.

METHODS

Before the actual experiment, the individual olfactory threshold for the rose-like odorant phenylethyl alcohol (PEA) was assessed separately for the left and right nostril using the "Sniffin' Sticks" test, and ratings for odor intensity and pleasantness were collected. After applying a nasal clip continuously delivering PEA odor to one nostril for 10 min and 2 h, respectively, threshold, intensity, and pleasantness were reassessed immediately after clip removal.

RESULTS

In the group of 80 participants (younger adults-mean age 27.7 ± 4.5 years; older adults-mean age 61.5 ± 4.7 years), olfactory thresholds were already significantly elevated after just 10 min, and this habituation was even more pronounced after 2 h. This effect could be observed bilaterally even though significantly more distinct on the exposed side. Older participants generally exhibited a more pronounced habituation on the exposed side after 2 h compared to the younger participants.

CONCLUSION

The results indicate that older people experience more notable habituation after extended exposure to odors. This is most likely due to the compromised olfactory function in age. Although older and younger subjects scored in the normosmic range when tested with standardized olfactory tests, the stress on the system after exposure to an odor clearly revealed the lower functionality of the aging sense of smell.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:3765-3768, 2024.

Small effects of olfactory identification and discrimination on global cognitive and executive performance over 1 year in aging people without a history of age-related cognitive impairment

Olfactory and cognitive performance share neural correlates profoundly affected by physiological aging. However, whether odor identification and discrimination scores predict global cognitive status and executive function in healthy older people with intact cognition is unclear. Therefore, in the present study, we set out to elucidate these links in a convenience sample of 204 independently living, cognitively intact healthy Czech adults aged 77.4 ± 8.7 (61-97 years) over two waves of data collection (one-year interval). We used the Czech versions of the Montreal Cognitive Assessment (MoCA) to evaluate global cognition, and the Prague Stroop Test (PST), Trail Making Test (TMT), and several verbal fluency (VF) tests to assess executive function. As a subsidiary aim, we aimed to examine the contribution of olfactory performance towards achieving a MoCA score above vs. below the published cut-off value. We found that the MoCA scores exhibited moderate associations with both odor identification and discrimination. Furthermore, odor identification significantly predicted PST C and C/D scores. Odor discrimination significantly predicted PST C/D, TMT B/A, and standardized composite VF scores. Our findings demonstrate that olfaction, on the one hand, and global cognition and executive function, on the other, are related even in healthy older people.

Head and neck complications of cancer therapies: taste and smell

Sensory deficits affect awareness of the environment and information processing, leading to dysfunction that may have significant consequences. Deterioration of taste and/or smell sensation has been linked to impaired nutritional intake, and overall decreased quality of life (QoL). Recent data suggest that loss of these senses is also associated with cognitive decline and worse overall cancer treatment prognosis. Cancer therapies have commonly been associated with sensory deterioration. We review these associations with taste and smell in light of new findings and discuss potential prophylactic and therapeutic modalities for taste and smell function.

Maximizing Participation in Olfactory Training in a Sample with Post-COVID-19 Olfactory Loss

PURPOSE

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.

Evaluation of Mild Cognitive Impairment through Perientorhinal/Hippocampal Imaging and Comprehensive Neuropsychological and Psychophysical Assessment

Mild cognitive impairment (MCI) is a significant concern as it is a risk factor for AD progression, and early detection is vital in order to delay dementia onset and enable potential therapeutic interventions. Olfactory impairment is recognized as a predictive biomarker in neurodegenerative processes. The aims of this study were to explore the degree of entorhinal cortical atrophy (ERICA) and the severity of MCI symptoms; to analyze magnetic resonance imaging (MRI) results for the entorhinal cortex, parahippocampal gyrus, peri entorhinal cortex, and the cerebellar tentorium; and to perform a comprehensive neuropsychological and psychophysical assessment. The main results highlighted that in our sample-multidomain amnesic MCI patients with hyposmic symptomatology-we found that ERICA scores were associated with the severity of anxiety symptomatology. One possible hypothesis to explain this observation is that anxiety may contribute to neurodegenerative processes by inducing chronic stress and inflammation. Future research should consider the longitudinal development of neuropsychological scores, anxiety disorders, and brain atrophy to determine their potential predictive value for MCI progression. These findings suggest the importance of psychological factors in MCI progression and the utility of neuropsychological assessment alongside neuroimaging techniques for early detection and follow-up in MCI patients.

Children and adolescents with primary headaches exhibit altered sensory profiles - a multi-modal investigation

BACKGROUND

Pediatric headache is an increasing medical problem that has adverse effects on children's quality of life, academic performance, and social functioning. Children with primary headaches exhibit enhanced sensory sensitivity compared to their healthy peers. However, comprehensive investigations including multimodal sensory sensitivity assessment are lacking. This study aimed to compare sensory sensitivity of children with primary headaches with their healthy peers across multiple sensory domains.

METHODS

The study included 172 participants aged 6 to 17 years (M = 13.09, SD = 3.02 years; 120 girls). Of these 80 participants were patients with migraine, 23 were patients with tension-type headache, and 69 were healthy controls. The following sensory measures were obtained: Mechanical Detection Threshold (MDT), Mechanical Pain Threshold (MPT), Mechanical Pain Sensitivity (MPS), detection and pain threshold for Transcutaneous Electrical Nerve Stimulation (TENS), olfactory and intranasal trigeminal detection threshold, and odor identification ability. Sensory sensitivity was compared between groups with a series of Kruskal-Wallis tests. Binomial regression models were used to compare the relative utility of sensory sensitivity measures in classifying participants into patients and healthy controls, as well as into patients with migraine and tension-type headache.

RESULTS

Patients with migraine had lower MPT measured at the forearm than patients with tension-type headaches and healthy controls. MPS was higher in patients with migraine than in healthy controls. All patients with headaches had lower detection threshold of TENS and higher olfactory sensitivity. Healthy controls showed increased intranasal trigeminal sensitivity. Scores in MPS, TENS, and olfactory and trigeminal thresholds were significantly predicting presence of primary headaches. Additionally, scores in MPT, olfactory and trigeminal threshold were positive predictors of type of headache.

CONCLUSIONS

Children with primary headaches exhibit different sensory profiles than healthy controls. The obtained results suggest presence of increased overall, multimodal sensitivity in children with primary headaches, what may negatively impact daily functioning and contribute to further pain chronification.

TRIAL REGISTRATION

The study was registered in the German Registry of Clinical Trials (DRKS) DRKS00021062.

Smell and Taste Alterations in Patients Receiving Curative or Palliative Chemotherapy-The CONKO 021-ChemTox Trial

Previous data regarding chemotherapy-induced olfactory and gustatory dysfunction (CIOGD) are heterogeneous due to inconsistent study designs and small numbers of patients. To provide consistent, reliable data, we conducted a cohort study using standardized testing. Patients diagnosed with lymphoma, leukemia, or gastrointestinal malignancies were examined up to five times (T1 to T5), beginning prior to chemotherapy. We examined patients receiving temporary treatment up to 12 months post-therapy. Clinical assessment included extensive questionnaires, psychophysical tests of olfactory and gustatory function, and measurement of peripheral neuropathy. Statistical analysis included non-parametric tests to evaluate the longitudinal development of CIOGD. Our data (n = 108) showed a significant decline in olfactory and gustatory testing during chemotherapy (p-values < 0.001). CIOGD appeared stronger among patients above 60 years, while sex did not matter significantly. However, we identified distinct associations between CIOGD and reported anorexia as well as with higher neuropathy scores. Self-assessment appeared less sensitive to chemosensory dysfunction than psychophysical testing. Post-therapy, olfactory and gustatory function regenerated, though baseline levels were not attained within 6 to 12 months. In conclusion, our data highlight the wide prevalence and slow recovery of CIOGD. Understanding CIOGD as a potential neurotoxic effect may disclose new therapeutic prospects.

Phenoconversion in pure autonomic failure: a multicentre prospective longitudinal cohort study

We aimed to describe the clinical features of patients with pure autonomic failure (PAF) preceding phenoconversion that could be useful as predictive markers for advancing α-synuclein-associated neurodegeneration of the brain. Patients diagnosed with PAF were evaluated at eight centres (seven US-based and one European) and enrolled in a longitudinal observational cohort study (NCT01799915). Subjects underwent detailed assessments of motor, sleep, olfactory, cognitive and autonomic function and were followed prospectively to determine whether they developed parkinsonism or dementia for up to 10 years. We identified incident cases of Parkinson's disease (PD), dementia with Lewy bodies (DLB) or multiple system atrophy (MSA) and computed hazard ratios for phenoconversion as functions of clinical features. A total of 209 participants with PAF with a median disease duration of 6 years (IQR: 3-10) were enrolled. Of those, 149 provided follow-up information at an office or telemedicine visit. After a mean follow-up duration of 3 years, 48 (33%) participants phenoconverted (42% to PD, 35% to DLB and 23% to MSA). Faster phenoconversion from study enrolment to any diagnosis was associated with urinary and sexual dysfunction [hazard ratio (HR) 5.9, 95% confidence interval (CI): 1.6-22 and HR: 3.6, 95% CI: 1.1-12] followed by subtle motor signs (HR: 2.7, 95% CI: 1.2-6), trouble swallowing (HR 2.5, 95% CI: 1.4-4.5) and changes in speech (HR:2.4, 95% CI:1.1-4.8) at enrolment. Subjects reporting deterioration of handwriting were more likely to phenoconvert to PD (HR: 2.6, 95% CI: 1.1-5.9) and those reporting difficulty handling utensils were more likely to phenoconvert to DLB (HR: 6.8, 95% CI: 1.2-38). Patients with a younger age of PAF onset (HR: 11, 95% CI: 2.6-46), preserved olfaction (HR: 8.7, 95% CI: 1.7-45), anhidrosis (HR: 1.8, 95% CI: 1-3.1, P = 0.042) and severe urinary problems (HR 1.6, 95% CI: 1-2.5, P = 0.033) were more likely to phenoconvert to MSA. The best autonomic predictor of PD was a blunted heart rate increase during the tilt-table test (HR: 6.1, 95% CI: 1.4-26). Patients with PAF have an estimated 12% (95% CI: 9-15%) per year annual risk following study entry of phenoconverting to a manifest CNS synucleinopathy.

High prevalence of long-term olfactory disorders in healthcare workers after COVID-19: A case-control study

BACKGROUND

More than a year after recovering from COVID-19, a large proportion of individuals, many of whom work in the healthcare sector, still report olfactory dysfunctions. However, olfactory dysfunction was common already before the COVID-19 pandemic, making it necessary to also consider the existing baseline prevalence of olfactory dysfunction. To establish the adjusted prevalence of COVID-19 related olfactory dysfunction, we assessed smell function in healthcare workers who had contracted COVID-19 during the first wave of the pandemic using psychophysical testing.

METHODS

Participants were continuously tested for SARS-CoV-2 IgG antibodies since the beginning of the pandemic. To assess the baseline rate of olfactory dysfunction in the population and to control for the possibility of skewed recruitment of individuals with prior olfactory dysfunction, consistent SARS-CoV-2 IgG naïve individuals were tested as a control group.

RESULTS

Fifteen months after contracting COVID-19, 37% of healthcare workers demonstrated a quantitative reduction in their sense of smell, compared to only 20% of the individuals in the control group. Fifty-one percent of COVID-19-recovered individuals reported qualitative symptoms, compared to only 5% in the control group. In a follow-up study 2.6 years after COVID-19 diagnosis, 24% of all tested recovered individuals still experienced parosmia.

CONCLUSIONS

In summary, 65% of healthcare workers experienced parosmia/hyposmia 15 months after contracting COVID-19. When compared to a control group, the prevalence of olfactory dysfunction in the population increased by 41 percentage points. Parosmia symptoms were still lingering two-and-a half years later in 24% of SARS-CoV-2 infected individuals. Given the amount of time between infection and testing, it is possible that the olfactory problems may not be fully reversible in a plurality of individuals.

Development and validation of the MultiScent-20 digital odour identification test using item response theory

Although validated and reliable psychophysical tests of olfactory function are available, an easy-to-use and feasible test has yet to be developed. This study aimed to design a digital odour identification test, evaluate its validity, assess its reliability, establish a normative curve, and explore the impact of demographic factors. The odour identification test was presented with the Multiscent-20, a hand-held, tablet-like digital scent device that features an integrated odour digital delivery system. The identification performance on the 20 odours was assessed using item response theory (IRT). The normative curve was established by administering the test to a large sample of participants (n = 1299). The mean identification score was 17.5 (SD = 2.1). The two-parameter logistic IRT model provided the best fit, revealing variation in item discrimination and difficulty parameters. Educational attainment influenced performance, with primary education associated with lower scores. Additionally, sex was not found to be associated with performance. This study provides initial evidence supporting the validity and reliability of use of the Multiscent-20 as a digital odour identification test. The test's automation and portability enable the standardized delivery of olfactory stimuli and efficient automatic recording and scoring of responses.