Relationship between olfactory and gustatory functions: The Iwaki health promotion project 2019.

OBJECTIVE: Olfactory and gustatory functions are important sensory aspects in humans. Although they are believed to influence each other, their interrelationship is not well understood. In this study, we aimed to investigate the relationship between the olfactory and gustatory functions based on the results of a large-scale epidemiological study (Iwaki Health Promotion Project) of the general local population. METHODS: We analyzed 565 participants who underwent taste and olfactory tests in the 2019 Iwaki Project. Gustatory function was tested for four taste qualities (sweet, sour, salty, and bitter) using whole-mouth taste tests. Olfactory function was tested using the University of Pennsylvania Smell Identification Test modified for Japanese (UPSIT-J). We evaluated sex-related differences between olfactory and gustatory functions and the effects of various factors on olfactory identification using multivariate analysis. Furthermore, we compared the percentage of accurate UPSIT-J responses between the normal and hypogeusia groups. We also analyzed the effects of taste and olfactory functions on eating. RESULTS: Olfactory and gustatory functions were lower in men than in women. Among the four taste qualities, salty taste was the most closely associated with olfactory identification ability, with lower olfactory scores of salty taste in the hypogeusia group than in the normal group. Moreover, the hyposmia group had higher daily salt intake than the normal olfaction group in women. CONCLUSION: These results suggest that olfactory identification tests may be useful in predicting elevated salt cognitive thresholds, leading to a reduction in salt intake, which may contribute to hypertension prevention.

Age-dependent appearance of SARS-CoV-2 entry sites in mouse chemosensory systems reflects COVID-19 anosmia-ageusia symptoms.

COVID-19 pandemic has given rise to a collective scientific effort to study its viral causing agent SARS-CoV-2. Research is focusing in particular on its infection mechanisms and on the associated-disease symptoms. Interestingly, this environmental pathogen directly affects the human chemosensory systems leading to anosmia and ageusia. Evidence for the presence of the cellular entry sites of the virus, the ACE2/TMPRSS2 proteins, has been reported in non-chemosensory cells in the rodent's nose and mouth, missing a direct correlation between the symptoms reported in patients and the observed direct viral infection in human sensory cells. Here, mapping the gene and protein expression of ACE2/TMPRSS2 in the mouse olfactory and gustatory cells, we precisely identify the virus target cells to be of basal and sensory origin and reveal the age-dependent appearance of viral entry-sites. Our results propose an alternative interpretation of the human viral-induced sensory symptoms and give investigative perspectives on animal models.

Olfactory and Gustatory Function in Patients With Different Types of Maxillofacial Trauma.

OBJECTIVES/HYPOTHESIS: To investigate olfactory and gustatory function in patients with maxillofacial trauma and associated fractures. STUDY DESIGN: Retrospective cohort study. METHODS: Olfactory and gustatory function was assessed psychophysically in 124 patients who had sustained maxillofacial trauma with an associated fracture. Five groups were defined based on the fracture type: Le Fort, mandibular, nasal, orbital, and zygomatic. Olfaction was measured with Sniffin' Sticks (threshold, discrimination, identification [TDI] score) and gustation with the taste spray method. Patients self-rated olfactory and gustatory function on a visual analog scale prior to formal testing. RESULTS: Ten out of 124 patients were found to be anosmic (8%), with half of them found in the Le Fort (skull base) group. The Le Fort fracture group had significantly lower olfactory function than other fracture types (TDI score = 22.4 ± 10.7; P = .01; possible range = 1-48). The mean gustatory spray test score was 3.82 ± 0.4 (possible range = 0-4) without any intergroup differences. Self-rated olfactory function showed a correlation with the measured scores (r = 0.61, P < .001) across all groups. CONCLUSIONS: The present data show a significant effect of maxillofacial fracture type on the development of anosmia. Maxillofacial fractures involving the skull base, such as Le Fort fractures, are more likely to cause permanent smell loss, whereas the other fracture types are rarely associated with anosmia. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E331-E337, 2021.