Impaired chemosensory function and its relationship with clinical severity, emotional states, and cognition in patients with insomnia disorder: An exploratory study.

ObjectiveTo evaluate and compare the efficacy and safety of endoscopic neurectomy versus radiofrequency ablation targeting both the posterior nasal nerve (PNN) and lateral internal nasal branches of the anterior ethmoidal nerve (LINB-AEN) in patients with allergic rhinitis (AR).MethodsIn this prospective randomized controlled trial, adult patients with moderate to severe AR undergoing endoscopic nerve intervention from November 2023 to September 2025 were randomized to receive either neurectomy or ablation. Surgical targets included both PNN and LINB-AEN. Outcomes were assessed at 1, 3, and 6 months postoperatively and included nasal symptom visual analog scale (VAS), total nasal symptom score (TNSS), rhinoconjunctivitis quality of life questionnaire (RQLQ), total nasal resistance (TNR), olfactory function (VAS, QOD-NS, and Sniffin' Sticks), and adverse events.Results61 patients completed follow-up (neurectomy group: n = 30; ablation group: n = 31). Both groups achieved significant symptomatic improvement by 6 months (p < 0.001). The ablation group demonstrated significantly greater improvement in nasal obstruction (p < 0.001) and sneezing (p = 0.008) at 1 month, while the neurectomy group showed earlier improvement in rhinorrhea (p = 0.002). Both procedures improved nasal resistance. Neurectomy provided a faster, sustained nasal resistance improvement (p 3 months = 0.001, p 6 months = 0.003) with superior improvement in odor identification (p < 0.001) and TDI score (p = 0.005). Notably, no serious complications were reported. Additionally, symptoms of nasal dryness improved from baseline in both groups.ConclusionThis is the first randomized controlled study to compare dual-target endoscopic neurectomy and ablation for AR. Both approaches are effective and safe. Ablation offers faster symptom relief, while neurectomy provides superior long-term control of nasal airflow and olfactory function. Individualized surgical planning is recommended based on symptom profile and patient preference.Trial RegistrationChinese Clinical Trial Registry Identifier: ChiCTR2500111543Level of Evidence2.

BackgroundOlfactory and visual processing are sensitive biomarkers for cognitive impairment; however, unimodal assessments may fail to capture early deficits in higher order cognitive integration. When sensory cues are mismatched, multisensory processing induces crossmodal conflict that requires inhibitory control, which is particularly vulnerable in early neurodegeneration.ObjectiveWe developed RAPPIT (Rapid, massively APPlicable Identification Test), a color-modulated olfactory test to assess multisensory interference as an early marker of cognitive decline.MethodsRAPPIT includes 16 physically presented odors, with a digital application for task control and response recording. Answer options are displayed on color backgrounds derived from the MONEX-40 color profile, either congruent or incongruent with the presented odors. A total of 163 participants from the German population completed the assessment. Odor identification accuracy, effects of color congruence (ΔE00), associations with cognitive performance (Montreal Cognitive Assessment, MoCA), hedonic ratings, and depressive symptoms were analyzed.ResultsOdor identification declined with age. Participants aged ≥ 60 years, a group at increased risk for neurodegenerative disorders including Alzheimer's disease, showed reduced performance under incongruent conditions. Performance exhibited a non-linear relationship with color difference (ΔE00), declining at mid-range values. Accuracy was significantly associated with MoCA scores. Hedonic ratings varied with color cues, while no associations were found with depressive symptoms.ConclusionsThese findings demonstrate that differences between congruent and incongruent odor-color conditions capture cognitively relevant interference effects beyond unimodal olfactory or visual performance, supporting the utility of this approach for early detection of cognitive impairment in older adults, in clinical and home settings.

BackgroundObesity is a major global public health burden, yet the mechanisms underlying interindividual variability in treatment response remain poorly understood. Olfactory function influences eating behavior and may differ in individuals with obesity. However, evidence in pediatric populations is limited, and their responsiveness to weight loss remains unclear. This study aimed to assess olfactory function in children and adolescents with obesity before and after an inpatient weight loss intervention. Specifically, we examined whether olfactory performance is within normative values and whether it changes in response to weight reduction.MethodsSixty children and adolescents with overweight or obesity (13.0 ± 1.9 years, BMI z-score: 2.5 ± 0.5) underwent a structured inpatient rehabilitation program (mean duration: 38 ± 10 days) integrating nutrition therapy, physical activity, stress management, and behavioral modification. Olfactory function was assessed at baseline (T1, ~ 7 days after admission) and after the intervention (T2, ~ 27 days after T1) using the Sniffin’ Sticks Test©, comprising odor threshold, discrimination, and identification. At both time points, participants self-reported their perceived olfactory ability.ResultsAt T1, data were available for 59 participants; 50 completed the follow-up assessment at T2. Completers showed significant reductions in body weight and BMI z-score (p < .001). Olfactory function at T1 was largely within the normative range when compared with age-matched reference data. During weight loss, olfactory function remained largely stable: odor identification improved modestly (p = .003), whereas odor threshold and discrimination showed no significant changes and were not associated with weight loss. Self-reported olfactory ability showed weak correspondence with objective measures and remained unchanged.ConclusionsOlfactory function in children and adolescents with obesity was largely within the normative range and showed limited change during short-term inpatient weight loss. These findings suggest that olfactory alterations may not be a primary determinant of short-term treatment response. However, age- and domain-specific variability may still be relevant for how individuals perceive and respond to food-related cues, with potential implications for dietary adherence and long-term weight management. Future studies with normal-weight control groups should examine whether such variability contributes to differences in eating behavior and long-term outcomes.Trial registrationDRKS00005122.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12916-026-05007-3.

ABSTRACTObjectiveTo evaluate subjective and objective olfactory outcomes in patients undergoing endoscopic sinus surgery (ESS) for chronic rhinosinusitis with nasal polyps (CRSwNP).MethodsProspective, single‐center study including adult patients undergoing ESS for CRSwNP from July 2022 to May 2024. Olfactory status was assessed using the Sinonasal Outcome Test (SNOT‐22) and Sniffin' Sticks odor identification test preoperatively and at 1‐, 3‐, and 6‐months postoperatively.ResultsThirty‐six patients (45% female, mean age: 48 ± 14) were included. Among them, 47% had asthma, 53% had a history of previous sinus surgery, and 28% had aspirin‐exacerbated respiratory disease. Mean SNOT‐22 score decreased from 57 ± 20 to 22 ± 18, 15 ± 14, and 25 ± 19, at 1‐, 3‐, and 6‐months postoperatively, respectively (p < 0.001). Mean Sniffin' Sticks identification test score improved from 5.2 ± 4.4 odors identified (out of 16) to 7.9 ± 3.9, 8.3 ± 4.7, and 7.7 ± 4.9 points at 1‐, 3‐, and 6‐months postoperatively, respectively, with statistically significant improvements at 1‐ and 3‐months (p < 0.001) and at 6‐months (p = 0.012).ConclusionThis prospective study demonstrates improvements in subjective and objective measures of olfaction after ESS in patients with CRSwNP. While the sense of smell may be the most difficult symptom to address with surgical intervention, our study provides direct evidence that appropriate surgical intervention can in fact provide meaningful improvements to a large proportion of patients with nasal polyps. Longer‐term studies will be required to determine if these improvements will remain sustained.Level of Evidence3.

Due to an ageing population and increased life expectancy, Alzheimer's dementia (AD) is becoming increasingly important. Since AD is characteristically preceded by subjective cognitive decline (SCD) and mild cognitive impairment (MCI), innovative diagnostic tools and therapeutics are essential for diagnosis at an early stage. Olfactory dysfunction is commonly associated with cognitive decline, indicating its potential as adiagnostic marker. This study examined the association between olfactory function, evaluated with the Sniffin' Sticks Odor Identification Test (SS-OIT), and Assessment of Self-Reported Olfactory Functioning (ASOF) inventory across five cognitive subgroups (healthy controls [HC], SCD, non-amnestic MCI, amnestic MCI, and AD). Furthermore, this study investigated the utility of olfactory testing in screening for AD. This retrospective, single-center cross-sectional study was conducted at the Neurology Department of the Medical University of Vienna. The study included 958 participants during the period 2000-2023. Cognitive and olfactory functions were assessed using standardized neuropsychological and olfactory tools. Statistical analyses included descriptive measures, analysis of variance (ANOVA), model testing, and the receiver operating characteristic (ROC) methodology. Olfactory performance declined with increasing cognitive impairment, with the strongest contrast showing an effect size of r = 0.51 between HC and AD. The SS-OIT (area under the ROC curve [AUC]: 75.3%) and Olfactory-Related Quality of Life subscale (ORQ; AUC: 64.8%) were identified as the most effective in distinguishing AD, with the following recommended cut-offs: SS-OIT ≤ 9; Subjective Olfactory Capability (SOC) ≤ 6; Self-Reported Capability of Perceiving Specific Odors (SRP) ≤ 4.10; and ORQ ≤ 3.67. Olfactory functioning shows moderate reliability in distinguishing subgroups; nevertheless, the proposed cut-off values may be suitable for AD screening. Further studies are recommended to confirm our findings.

Olfactory deficits, especially in odor identification (OID), have been linked to Alzheimer's disease (AD), likely due to regional proteinopathy and atrophy in the olfactory brain circuit. Their cognitive and biological correlates across the clinical spectrum, particularly in individuals with no evident cognitive impairment, have been underexplored. This examination is relevant because many individuals of this group will not progress to dementia, and olfactory deficits may reflect ongoing pathological processes and could enrich risk stratification. We analyzed data from a cohort of 233 subjective cognitive impairment (SCI, n=152), mild cognitive impairment (MCI, n=50), and AD dementia (n=31) individuals from the Karolinska University Hospital Memory Clinic (Solna, Sweden). We examined the association of performance on the 16-item Sniffin' Sticks OID test (free and total [free or cued] identification scores) with a range of markers: cognitive performance, cerebrospinal fluid biomarkers, AD- and olfactory-related brain volumes, and white matter hyperintensities volume. We performed correlation analyses, generalized additive models, and threshold regressions, adjusted for sociodemographic factors and APOE status. OID performance was better in SCI compared to MCI and AD. Aβ42/40 ratio was positively associated with OID in SCI and AD, with APOE ε4 carriers driving this association in SCI. Hippocampal volume was positively associated with OID in AD. Higher volume of white matter hyperintensities was negatively associated with OID in MCI. The relationships of OID with Aβ42/40 and hippocampal volume were linear in the whole cohort. Worse verbal episodic memory performance was associated with lower OID scores only in the AD group. Free OID showed a broader and stronger pattern of associations with episodic memory and biomarkers compared with total OID. Threshold regression between free OID and Aβ42/40 identified a subthreshold value (<0.94) above the clinical cutoff (<0.86), capturing nine non-demented individuals within the gray zone between these cutoffs. Our findings support an association between amyloid levels and olfactory performance in the AD spectrum, underscoring the potential of smell tests as cost-effective tools in multimodal stratification frameworks. In dementia stages, medial temporal atrophy accompanied by memory impairment may be the main correlate of olfactory deficits.

Olfactory impairment in Huntington's disease: A systematic review and meta-analysis

The purpose of this study was to examine the relationship between serum 25(OH)D levels and olfactory function in adults, given the emerging recognition of vitamin D as a neurosteroid with potential influence on sensory pathways. Specifically, the study aimed to determine whether vitamin D status is associated with olfactory threshold and identification performance, to explore the presence of a biologically plausible dose-response pattern, and to assess the predictive value of serum vitamin D levels for olfactory dysfunction. In this cross-sectional study, 161 adults were enrolled, including 98 with vitamin D deficiency and 63 with sufficient levels. Serum 25(OH)D was measured by HPLC and categorized into four groups (< 10, 10-20, 20-30, ≥ 30 ng/mL). Olfactory threshold and identification were assessed using the Sniffin' Sticks rapid screening kit. Group comparisons, subgroup analyses, correlation tests, multiple linear regression, and ROC analysis (threshold < 7) were performed. Vitamin D-deficient participants had significantly lower threshold and identification scores than controls (p = 0.008 and p < 0.001). Both scores increased stepwise across vitamin D subgroups (p < 0.001). Serum 25(OH)D correlated positively with threshold (r = 0.302) and identification (r = 0.432) (both p < 0.001); in the deficiency group, the correlation persisted only for threshold. Vitamin D was an independent predictor of identification (β = 0.041; p < 0.001). ROC analysis indicated that severe vitamin D deficiency (cutoff ≈ 10 ng/mL) was strongly associated with threshold-level olfactory impairment (AUC 0.636; specificity 95%). Serum vitamin D level is associated with olfactory function, particularly odor identification, and shows a biologically plausible dose-response pattern. Vitamin D appears to be a specific risk indicator rather than a standalone diagnostic marker for olfactory dysfunction.

Identification of major odorants in shrimp stock-based tom yum kung and potential of shrimp stock on saltiness enhancement to tom yum kung

Safety-critical odor identification failure and cognitive performance in older U.S. adults: a cross-sectional NHANES analysis.

Previous work has shown that humans make consistent associations between odor and color. However, neurodiverse individuals, especially those with autism spectrum disorder (ASD), perceive and interpret sensory information differently from their neurotypical peers. Their sensory perceptual experiences can involve hypersensitivity or hyposensitivity, as well as deficits in multisensory integration, especially among younger individuals. In this study, we evaluated olfactory-visual associations among verbal individuals with ASD, attention deficit/hyperactivity disorder (ADHD), and a comparison group of children without neurodevelopmental disorders by means of an odor-color association task. We found that youth with ASD, ADHD, and without neurodevelopmental disorders experience olfactory perception in a similar manner, showing similar inconsistencies in terms of (verbal) odor identification and odor-color associations, while rating odors similarly in terms of (un)pleasantness, specifically for sour, salty, and spicy odors and sweet and fruity odors. This supports the notion that neurodivergent youth present individual variation in olfaction, but less so in perceived odor pleasantness, results that promote further exploration of odor-color associations within and across diverse populations.

ABSTRACTObjectivesInvoluntary tearing is an annoyingly common consequence of cutting onions. Little is known about who experiences so‐called “onion tears” and to what extent they experience them. Our aim with this study was to explore whether the degree of onion tearing is a phenotypic predictor of olfactory function and trigeminal sensitivity, assessed by both self‐report and psychophysical measures of chemosensory function.MethodsA total of 1001 participants (598 females; Mage 44 years) completed four subjective ratings of nasal function (subjective smelling ability, nasal sensitivity, trigeminal sensitivity, and nasal patency), three psychophysical tests (odor identification, AmmoLa intensity, and odor lateralization), and answered questions about the severity of their tearing while cutting onions.ResultsResults revealed that higher levels of onion tearing were associated with better self‐rated olfactory ability, nasal breathing, and higher sensitivity to nasal stinging/burning. No statistically significant relationship was found between the psychophysical tests of olfactory ability and degree of onion tearing. Performance on all measures was also analyzed across three different age brackets (18–35; 36–55; 56+ years) and yielded mixed findings related to subjective ratings of trigeminal sensitivity and olfactory function.ConclusionClinically, there is yet to be a universally accepted measure to determine subjective chemosensory sensitivity, and in particular, trigeminal sensitivity. Despite inconsistencies between the subjective and objective chemosensory tests, our findings suggest that asking someone about the severity of their tearing while cutting onions may be a useful addition to standard testing assessing chemosensory and trigeminal sensitivity.Level of Evidence3.

BackgroundIt is important to use odor threshold and odor identification (OI) tests to evaluate children's olfactory function. However, there is a lack of Chinese normative data obtained in a large sample for these tests.ObjectiveThe purpose of this study was to provide normative data for Chinese children regarding olfactory threshold (OT) and OI tests, as well as combined scores, which help clinicians distinguish between normosmia and dysfunction in clinical diagnosis.MethodsOlfactory testing was conducted using the "Sniffin' Sticks" OT test and the 12-item "U-Sniff" OI test; TI score was calculated as the sum of OT and OI scores. The data were collected from 450 children between the age of 5 and 17 years. In line with previous studies, participants were divided into subgroups regarding their age: (1) 5-8 years, (2) 9-11 years, and (3) 12-17 years.ResultsNormative data for OT, OI, and TI score were established across different age groups. Age was found to have a significant impact on OT, OI, and TI performance. Elder children achieved higher scores compared to younger children (P < 0.001 for all).ConclusionThis study offers normative data for evaluating the sense of smell in Chinese children using both the OT and OI tests. These tests can help differentiate between a normal sense of smell and dysfunction. Combining these two tests can provide a comprehensive evaluation of the olfactory function in children.

Anosmia and hyposmia, referring to total or partial smell loss, respectively, affect 3% to 20% of people. The Sniffin’ Sticks Extended Test, assessing odor threshold, discrimination, and identification (TDI), is a well-validated tool widely used in European and US clinics. However, its time and resource demands limit routine use. During the COVID-19 pandemic, several rapid smell tests were developed, yet their classification performance and agreement with established psychophysical measures remain underexplored. We compared 4 alternatives—the Visual Analog Scale for self-rated smell ability (VAS), the smell section of the Appetite, Hunger, and Sensory Perception questionnaire (AHSP), the Global Consortium for Chemosensory Research Smell Check (GCCR-Check), and the SCENTinel rapid smell test—against TDI scores in a longitudinal cohort of 96 adults (77 female patients; age 46.6 ± 10.5 yr) with post-COVID-19 smell dysfunction, assessed up to 5 times over 12 mo. Analyses used Generalized Estimating Equations for repeated measures, Bland–Altman plots for agreement and bias, and area under the receiver operating characteristic (AUC) curves for classification. No tool dominated across all TDI-defined categories. SCENTinel showed robust performance for anosmia (0.81) with the most balanced sensitivity–specificity trade-off among rapid tests, while GCCR-Check achieved the highest AUC for anosmia (0.88) and VAS best identified normosmia (0.73). Agreement analyses revealed systematic biases in self-report and rapid psychophysical tests. Rapid tools reliably detect anosmia, while classification performance decreases near diagnostic boundaries, particularly for normosmia. Combining brief self-report and short psychophysical measures may improve accuracy while maintaining feasibility for clinical and large-scale screening.

The nose knows danger: Linking olfactory deficits to suicidal behaviors in emerging adulthood.

Characterization of volatile aroma profiles and identification of key stale odorants in albino green tea during accelerated shelf-life storage

Olfactory dysfunction is a common nonmotor symptom and prodromal marker of Parkinson's disease (PD). Despite its early occurrence, hyposmia is frequently underrecognized, emphasizing the need for objective, culturally appropriate tools. The Indian smell identification test (INSIT) is widely used but relies on binary scoring, which may underestimate residual olfactory function. This study determines the prevalence of olfactory dysfunction in Indian persons with PD (PwPD) using INSIT and evaluates a modified version (mINSIT) with graded scoring as a preliminary proof-of-concept. Two independent cohorts were recruited. Phase 1 included 129 PwPD and 129 age- and sex-matched healthy controls (HCs) assessed with INSIT. Phase 2 included 108 PwPD and 50 HCs tested with INSIT and mINSIT. INSIT used standard binary scoring, while mINSIT captured gradations: nonperception, perception without recognition, cued recognition, and spontaneous recognition. INSIT identified hyposmia in 62% of PwPD versus 32.5% of HCs in phase 1, and 59.3% versus 30% in phase 2 ( P < 0.001). mINSIT revealed that many PwPD who failed odor identification still perceived odors, demonstrating perception-identification dissociation in 19-86% of cases. Graded scoring provided a more nuanced assessment of olfactory function, with a broader distribution of scores compared with binary scoring. The odors most discriminative between groups were mango, cardamom, and lemon. INSIT is limited by its binary outcome design, whereas mINSIT provides a potentially useful, culturally relevant preliminary tool that captures gradations of olfactory function and may improve detection. It addresses limitations of conventional binary scoring; however, formal validation in larger cohorts is required before it can be recommended for clinical use.

Unraveling the fishy odor of Laminaria japonica via headspace solid-phase microextraction gas chromatography-mass spectrometry, molecular docking and chemometrics: Key odorant identification and prediction-model construction.

The lasting effects of exercise on brain health in older adults are poorly documented. The aim of this study was to assess the long-term, post-intervention effects 4years after a 5-year exercise intervention on brain volumes and cognitive abilities in older adults. A total of 106 older adults (70-77years at baseline) from the randomized controlled trial (RCT) Generation 100 study randomized into high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or a control group following national physical activity guidelines for 5years were included. Post-intervention assessment was performed 9years after inclusion. Brain magnetic resonance imaging (MRI) and exercise characteristics were acquired at baseline and after 1, 3, 5, and 9years. Cognitive abilities were assessed with verbal list learning, pattern separation, and odor identification tests at baseline and 9years. Linear mixed models were used to examine the interaction between exercise group and time on brain volumes. The analyses were repeated, including self-reported exercise behaviors (intensity and duration) as covariates. To examine the general effect of exercise intensity independent of group, a separate model was run across all participants with self-reported exercise intensity as independent variable. For cognition, linear regressions examined associations between exercise group and self-reported exercise intensity on cognitive scores at 9years, and hippocampal volume loss over time on cognitive scores at 9years. Whether baseline peak oxygen uptake (VO2peak) predicted brain volumes and cognitive scores at 9years was tested with linear regression. The time × group interaction revealed greater hippocampal volume loss in the HIIT compared with the control group 4years after the intervention ended, similar to what was found during the intervention. We did not find that self-reported exercise behavior was associated with hippocampal volume over time. Across all participants, greater hippocampal volume loss was associated with poorer verbal memory at 9years. The test scores on verbal memory and pattern separation did, however, not differ between the groups, but the MICT, and trending for the HIIT group, had higher odor identification scores at 9years. Higher baseline VO2peak predicted larger cortical volume and better pattern separation score at 9years across intervention groups, in line with what was observed during the intervention. The control group, which followed the national physical activity guidelines, had the lowest hippocampal volume loss over time, even 4years after the end of a 5-year exercise intervention in fit older adults. Furthermore, higher baseline VO2peak provided protective effects on both cortical volume and pattern separation ability across almost a decade, independent of exercise group. ClinicalTrials.gov NCT01666340 (registered 16 August 2012).