Is the perception of odour pleasantness shared across cultures and ecological conditions? Evidence from Amazonia, East Africa, New Guinea, Malaysia and Poland.

What makes an odour pleasant or unpleasant? The inherent properties of the constituent chemical compounds, or the nose of the beholder, driven by idiosyncratic differences and culture-specific learning? Here, 582 individuals, including Tanzanian Hadza hunter-gatherers, Amazonian Tsimane' horticulturalists, Yali from the Papuan highlands and two industrialized populations (Poles, Malaysians), rated the pleasantness of 15 odour samples. We find considerable similarities in odour assessments across cultures, but our data do not fully support a claim regarding the universality of smell preferences. Despite cross-cultural similarities in olfactory assessments, probably driven by odour properties, we suggest that odour availability in ecological and cultural niches bears an undeniable effect on human odour preferences.

Does vaping affect the taste and smell perception? An exploratory study with New Zealand young adults.

OBJECTIVE: The study aimed to assess potential effects of vaping on individual taste and smell perception in a sample of young adult New Zealanders. DESIGN: This cross-sectional study measured taste and smell perception using intensity and hedonic ratings to two olfactory (i.e., vanillin, methional) and two gustatory stimuli (i.e., sucrose, monosodium glutamate), representing sweet and savoury flavours. Detection sensitivities to sucrose and vanillin were also assessed using a forced choice detection paradigm aligned with the signal detection framework. MANCOVAs were employed to compare sensory perception between groups based on vaping use frequency. Additional regression analyses were conducted to identify potential predictors of intensity and hedonic sensory ratings. SETTING: Participants were recruited from the University of Otago student population and surrounding neighbourhoods of Dunedin, New Zealand in 2023. PARTICIPANTS: The study included 213 university students (98 vapers and 115 non-vapers) RESULTS: We found a significant difference in hedonic ratings for vanillin, indicating a stronger preference among non-vapers. However, no other differences between the two groups were significant. Notably, the use of tobacco and mint flavours were emerged as significant predictors for hedonic responses to the savoury smell and sweet taste stimulus, respectively. No significant differences were observed between groups in the ability to detect weak stimuli. CONCLUSIONS: Our findings suggest that vape use, particularly with specific flavours, may be associated with alterations in hedonic responses to smells. This finding may have potential implications for how vaping affects on food preferences and dietary choices.

Olfactory Response to Altitude Hypoxia: A Pilot Study During a Himalayan Trek.

The adaptation of olfaction to extreme environments is an area of limited understanding. This study aimed to get insights into the factors that constrain olfactory function at high altitudes. To this end, we compared the results of smell tests performed on the same subjects at low (665 m) and high altitude (4,780 m) during the "Kanchenjunga Exploration and Physiology" project in the Himalayas. The most distinct adaptive differences found at high altitude were reductions in the odor intensity, color-odor bimodal association, and memory, and increases in flavor perception. Physiological adaptations of the sense of smell resulting from exposure to hypoxia at altitude may have explanatory validity in unraveling the mechanisms that shape changes in olfactory function in the processes of aging and neurodegenerative diseases.

Effects of septorhinoplasty on smell perception.

PURPOSE: To assess whether significant changes in smell perception occur after septorhinoplasty, and evaluate whether septum deviation, allergic rhinitis, and surgical technique affect postoperative smell perception. METHODS: Thirty-four patients (> 18 years old) awaiting septorhinoplasty were included, while those with previous severe hyposmia or anosmia were excluded. The participants self-assessed their smell perception using a 100-mm visual analogue scale (VAS), where 0 mm indicated the inability to smell and 100 mm indicated normal smell perception. The University of Pennsylvania Smell Identification Test (UPSIT) was applied before the procedure, and 4 and 12 weeks after surgery. RESULTS: The UPSIT score showed no significant changes at 4 (p = 0.59; 95% CI - 0.35 to + 2) or 12 weeks (p = 0.16; 95% CI - 1.13 to + 0.66). A comparison of the VAS scores before and 4 weeks after surgery (p = 0.62; 95% CI - 0.63 to + 0.39) yielded similar results. However, the average VAS scores improved 12 weeks after surgery (p = 0.007; 95% CI + 0.22 to + 1.30). Olfactory function, measured using the UPSIT, was not influenced by open or closed surgical techniques (p ≥ 0.10), the presence or absence of rhinitis (p ≥ 0.15), or obstructive septum deviation (p ≥ 0.38). Twelve weeks after surgery, self-evaluated smell perception was better in patients who underwent a closed procedure rather than an open procedure (p = 0.006; 95% CI: -1.39 to -0.37). CONCLUSION: A validated test demonstrates that septorhinoplasty does not compromise smell perception 4 and 12 weeks after surgery. However, it might improve smell perception by the self-report observation.

A longitudinal study of altered taste and smell perception and change in blood pressure.

BACKGROUND AND AIMS: Previous studies suggest that olfactory receptors, which mediate smell chemosensation, are located in the kidney and involved in blood pressure regulation. Mammalian epithelial sodium channels located in taste receptor cells are also found to participate in blood pressure regulation. However, there is currently no human study that has examined the association between taste and smell function and blood pressure. We thus conducted a longitudinal study to examine whether participants with altered taste and smell perception had larger increases in blood pressure compared with those without altered perception in a community-based cohort. METHODS AND RESULTS: The study included 5190 Chinese adults (4058 men and 1132 women) who were normotensive at baseline. Taste and smell perception were assessed via questionnaire in 2012 (baseline). Blood pressure was measured in 2012 and 2014 to determine relative change in blood pressure. Mean differences of 2-year blood pressure change and 95% confidence intervals (CIs) across four categories of taste and smell perception were calculated after adjusting for known risk factors for hypertension. After adjusting for potential confounders, individuals with altered taste and smell perception had larger increases in systolic blood pressure (adjusted mean difference = 5.1 mmHg, 95% CI: 0.1-10.0, p-value: 0.04) and mean arterial pressure (adjusted mean difference = 3.8 mmHg, 95% CI: 0.4-7.1, p-value: 0.03) after two years of follow-up compared with those having neither altered taste nor altered smell perception. No significant association was observed in individuals with altered taste or smell perception only. CONCLUSION: Our results suggest an association between chemosensory function and blood pressure.

Prevalence and Magnitude of Olfactory Dysfunction in Allergic Rhinitis.

BACKGROUND: Although allergic rhinitis (AR) can negatively impact the ability to smell, the degree to which this occurs is not clear and prevalence estimates vary among studies. This study had 4 main objectives: (1) To estimate the prevalence and the degree of olfactory dysfunction in AR patients; (2) To compare olfactory perception between AR patients with different persistence and severity of symptoms and determine if olfactory testing may aid in differentiating among Allergic Rhinitis and its Impact on Asthma (ARIA) groups; (3) To determine whether allergic reactions to different allergens differentially impact olfactory function, and (4) Verify possible changes in the olfactory epithelium (OE) caused by AR. METHODS: One hundred thirty-three patients with AR and one hundred controls were tested. The main outcome was the score in University of Pennsylvania Smell Identification Test (UPSIT®). The OE was examined using immunofluorescence markers for neuronal activity, apoptosis, oxidative stress, signal transduction, eosinophils, and epithelial thickness. RESULTS: Prevalence of olfactory dysfunction in the AR patients was higher (AR: 42.9% vs controls: 9%, P < .001). No difference was found either between intermittent and persistent disease cases (P = .58) or between cases with mild and those with moderate/severe symptomatology (P = .33). Lower olfactory capacity was not associated with the reaction to more (P = .48) or diverse types of allergens (Ps > .05). Although not significant, patients with AR had a greater amount of eosinophilia and a lower amount of cAMP (cyclic adenosine monophosphate) in the OE. CONCLUSION: The study highlights a higher prevalence of olfactory dysfunction in AR patients compared to controls, but olfactory testing may not effectively differentiate AR severity or allergen sensitivities. Although trends suggest potential pathophysiological changes in the OE of AR patients, further research is needed to validate these findings.

Characteristics of Chemosensory Perception in Long COVID and COVID Reinfection.

Emerging data suggest an increasing prevalence of persistent symptoms in individuals affected by coronavirus disease-19 (COVID-19). The objective of this study was to determine the relative frequency of altered taste and smell in COVID reinfection (multiple COVID positive tests) and long COVID (one COVID positive test). We sent an electronic survey to patients in the Indiana University Health COVID registry with positive COVID test results, querying if they were experiencing symptoms consistent with long COVID including altered chemosensory perceptions. Among the 225 respondents, a greater long COVID burden and COVID reinfection was observed in women. Joint pain was reported as the most common symptom experienced by 18% of individuals in the long COVID cohort. In the COVID reinfection cohort >20% of individuals reported headache, joint pain, and cough. Taste perception worse than pre-COVID was reported by 29% and 42% of individuals in the long COVID and COVID reinfection cohorts, respectively. Smell perception worse than pre-COVID was reported by 37% and 46% of individuals in long COVID and COVID reinfection cohorts, respectively. Further, Chi-square test suggested significant association between pre-COVID severity of taste/smell perception and headache in both cohorts. Our findings highlight the prevalence of persistent chemosensory dysfunction for two years and longer in long COVID and COVID reinfection.

Reduced Olfactory Bulb Volume in Obesity and Its Relation to Metabolic Health Status.

Smell perception plays an important role in eating behavior and might be involved in body weight gain. Since a body of literature implies that olfactory perception and function is hampered in obesity, we here investigate neuroanatomical correlates of this phenomenon. We assessed olfactory bulb (OB) volume with magnetic resonance imaging in 67 healthy participants with a body mass index (BMI) from 18.9 to 45.4 kg/m2 (mean = 28.58 ± 6.64). Moreover, we obtained psychophysiological data on olfactory ability (Sniffin' Sticks, Food associated odor test) and self-report measurements on eating behavior. Additionally, we collected parameters associated with metabolic health in obesity (waist-hip ratio, waist-height ratio, leptin levels, body fat percentage, fat mass index, insulin resistance) to investigate recently proposed mechanistic explanatory models of why olfaction may be altered in obesity. We showed that OB volume was significantly lower in participants with obesity when compared to those of normal weight. Moreover, we found weak to moderate negative correlations between OB volume and BMI and related measures of metabolic health, especially leptin, body fat percentage, waist-height ratio and insulin resistance. However, neither OB volume nor BMI were related to olfactory function in our young and healthy sample. Nevertheless, our results provide first indications that obesity is associated with brain anatomical changes in the OBs.

The Taste and Smell Protocol in the 2011-2014 US National Health and Nutrition Examination Survey (NHANES): Test-Retest Reliability and Validity Testing.

INTRODUCTION: The US NHANES 2011-2014 protocol includes a taste and smell questionnaire (CSQ) in home-based interviews and brief assessments in mobile exam centers. We report the short- and longer-term test-retest reliability and validity of this protocol against broader chemosensory measures. METHODS: A convenience sample of 73 adults (age=39.5±20.8 years) underwent the NHANES protocol at baseline, 2 weeks and 6 months. For taste, participants rated intensities of two tastants (1 M NaCl, 1 mM quinine) applied to the tongue tip and three tastants (1 M NaCl, 1 mM quinine, 0.32 M NaCl) sampled with the whole mouth. Smell function was assessed with a Pocket Smell Test™ (PST; eight-item odor identification test). The CSQ asked about chemosensory problems, distortions, and age-related changes. Broader baseline measurements were a 40-item olfactometer-generated identification task and additional whole-mouth taste intensities (1 M sucrose, 32 mM citric acid, 3.2 mM propylthiouracil). RESULTS: Intraclass correlations (ICCs) for NHANES taste measures showed moderate-to-good agreement after 2 weeks and 6 months (ICCs 0.42-0.71). Whole-mouth quinine intensity was significantly correlated with other taste intensities, supporting its utility as a marker for overall taste functioning. Olfactory classification from PSTs agreed for 98.5 % of participants across 2 weeks (κ=0.85; 95 % CI 0.71-0.99) and had good correspondence with the olfactometer task. CSQ items showed good-to-excellent agreement over 6 months (ICCs 0.66-0.90). CONCLUSIONS: These findings further support that the NHANES chemosensory protocol has moderate-to-good test-retest reliability when administered to healthy, educated adults. Despite being a brief procedure with limited measures, the NHANES taste and smell assessments provided good information when compared to broader measures of taste and smell function.

Facial Expression in Response to Smell and Taste Stimuli in Small and Appropriate for Gestational Age Newborns.

Small for gestational age newborns can later suffer from eating difficulties and slow growth. Nutritional preferences can be influenced by changes in sensory perception of smell and taste. To determine whether these could be detected at birth, the authors examined the different recognition pattern of smell and taste in small for gestational age newborns compared to appropriate for gestational age controls, as expressed by gusto-facial and naso-facial reflexes. The authors performed video analysis of facial expressions of 10 small for gestational age and 12 control newborns exposed to various tastes and smells. No difference in the facial recognition patterns for taste or smell was demonstrated between small for gestational age and controls, except for perception of distilled water. Newborns show recognizable patterns of facial expression in response to taste and smell stimuli. Perception of taste and smell in small for gestational age newborns is not different from controls, as measured by the method of facial recognition.