Characterization of pathological changes in the olfactory system of mice exposed to methylmercury.

Methylmercury (MeHg) is a well-known environmental neurotoxicant that causes severe brain disorders such as Minamata disease. Although some patients with Minamata disease develop olfactory dysfunction, the underlying pathomechanism is largely unknown. We examined the effects of MeHg on the olfactory system using a model of MeHg poisoning in which mice were administered 30 ppm MeHg in drinking water for 8 weeks. Mice exposed to MeHg displayed significant mercury accumulation in the olfactory pathway, including the nasal mucosa, olfactory bulb, and olfactory cortex. The olfactory epithelium was partially atrophied, and olfactory sensory neurons were diminished. The olfactory bulb exhibited an increase in apoptotic cells, hypertrophic astrocytes, and amoeboid microglia, mainly in the granular cell layer. Neuronal cell death was observed in the olfactory cortex, particularly in the ventral tenia tecta. Neuronal cell death was also remarkable in higher-order areas such as the orbitofrontal cortex. Correlation analysis showed that neuronal loss in the olfactory cortex was strongly correlated with the plasma mercury concentration. Our results indicate that MeHg is an olfactory toxicant that damages the central regions involved in odor perception. The model described herein is useful for analyzing the mechanisms and treatments of olfactory dysfunction in MeHg-intoxicated patients.

Phantosmia during proton radiation and differences in frequency of phantosmia rates based on proton craniospinal irradiation technique for pediatric brain tumor patients.

BACKGROUND: Unusual olfactory perception, often referred to as "phantosmia" or "cacosmia" has been reported during brain radiotherapy (RT), but is infrequent and does not typically interfere with the ability to deliver treatment. We seek to determine the rate of phantosmia for patients treated with proton craniospinal irradiation (CSI) and identify any potential clinical or treatment-related associations. METHODS: We performed a retrospective review of 127 pediatric patients treated with CSI, followed by a boost to the brain for primary brain tumors in a single institution between 2016 and 2021. Proton CSI was delivered with passive scattering (PS) proton technique (n = 53) or pencil beam scanning technique (PBS) (n = 74). Within the PBS group, treatment delivery to the CSI utilized a single posterior (PA) field (n = 24) or two posterior oblique fields (n = 50). We collected data on phantom smell, nausea/vomiting, and the use of medical intervention. RESULTS: Our cohort included 80 males and 47 females. The median age of patients was 10 years (range: 3-21). Seventy-one patients (56%) received concurrent chemotherapy. During RT, 104 patients (82%) developed worsening nausea, while 63 patients (50%) reported episodes of emesis. Of those patients who were awake during CSI (n = 59), 17 (29%) reported phantosmia. In the non-sedated group, we found a higher rate of phantosmia in patients treated with PBS (n = 16, 42%) than PS (n = 1, 4.7%) (p = .002). Seventy-eight patients (61%) required medical intervention after developing nausea/vomiting or phantosmia during RT. Two patients required sedation due to the malodorous smell during CSI. We did not find any significant difference in nausea/vomiting based on treatment technique. CONCLUSION: Proton technique significantly influenced olfactory perception with greater rates of phantosmia with PBS compared to PS. Prospective studies should be performed to determine the cause of these findings and determine techniques to minimize phantosmia during radiation therapy.

[Systematic review and Meta-analysis of efficacy and safety of Bidouyan Oral Liquid in treatment of rhinosinusitis].

This study aimed to systematically review the efficacy and safety of Bidouyan Oral Liquid in the treatment of rhinosinu-sitis(RS). CNKI, Wanfang, SinoMed, VIP, Cochrane Library, PubMed, EMbase, Web of Science, and Ovid were searched for the randomized controlled trial(RCT) of Bidouyan Oral Liquid for the treatment of RS patients. Moreover, the reference lists and the grey literature were searched manually. Two researchers independently screened the literature and extracted data. The Cochrane collaboration's tool for assessing risk of bias(RoB 2.0) in randomized trial was used to assess the methodological quality of the included stu-dies. Meta-analysis was performed in RevMan 5.3 and Stata 12.0, and the grades of recommendation, assessment, development and evaluation(GRADE) was employed to evaluate the quality of evidence. A total of 54 RCTs(35 with drug combinations and 19 with single drugs) comprising 7 511 patients(3 973 in the observation group and 3 538 in the control group) were included. Meta-analysis showed that Bidouyan Oral Liquid + conventional treatment was superior to conventional treatment alone in increasing the total response rate(RR=1.19, 95%CI[1.15, 1.24], P<0.000 01) and decreasing the Lund-Kennedy scores(MD=-1.94, 95%CI[-2.61,-1.26], P<0.000 01), Lund-Mackay scores(MD=-2.14, 95%CI[-2.98,-1.31], P<0.000 01), and visual analogue scale(VAS) scores(MD_(total VAS scores)=-1.28, 95%CI[-1.56,-1.01], P<0.000 01; MD_(nasal congestion VAS scores)=-0.58, 95%CI[-0.89,-0.27], P=0.000 2; MD_(runny nose VAS scores)=-0.61, 95%CI[-0.93,-0.29], P=0.000 2; MD_(olfactory dysfunction VAS scores)=-0.43, 95%CI[-0.52,-0.34], P<0.000 01; MD_(head and facial pain VAS scores)=-0.41, 95%CI[-0.57,-0.26], P<0.000 01). Furthermore, the combined treatment outperformed conventional treatment alone in improving the mucociliary transport rate(MTR)(MD=1.64, 95%CI[1.08, 2.20], P<0.000 01) and lowering the levels of inflammatory cytokines{tumor necrosis factor-α(TNF-α)(SMD=-1.95, 95%CI[-2.57,-1.33], P<0.000 01), interleukin-6(IL-6)(SMD=-2.64, 95%CI[-4.08,-1.21], P=0.000 3)} in RS patients. In addition, the combined treatment did not increase the incidence of adverse reactions(RR=0.83, 95%CI[0.44, 1.57], P=0.57). Bidouyan Oral Liquid was superior to conventional treatment in increasing total response rate(RR=1.25, 95%CI[1.18, 1.32], P<0.000 01), decreasing the Lund-Kennedy(P<0.01) and Lund-Mackay scores(P<0.05), alleviating major symptoms(P_(total VAS scores)<0.01; P_(nasal congestion VAS scores)<0.01; P_(runny nose VAS scores)<0.01; P_(olfactory dysfunction VAS scores)<0.05; P_(head and facial pain VAS scores)<0.01), and decreasing adverse reactions(P=0.03). The results showed that either Bidouyan Oral Liquid or Bidouyan Oral Liquid + conventional treatment can increase the total response rate, decrease the Lund-Kennedy and Lund-Mackay scores, and mitigate major symptoms. In addition, Bidouyan Oral Liquid + conventional treatment improved MTR and reduced the expression of TNF-α and IL-6 without causing serious adverse events. However, due to the limited methodological quality of the included studies, large-sample and high-quality RCTs are needed to provide evidence support.

Three Cases of Reported Improvement in Microsmia and Anosmia Following Naturalistic Use of Psilocybin and LSD.

Cultural awareness of anosmia and microsmia has recently increased due to their association with COVID-19, though treatment for these conditions is limited. A growing body of online media claims that individuals have noticed improvement in anosmia and microsmia following classic psychedelic use. We report what we believe to be the first three cases recorded in the academic literature of improvement in olfactory impairment after psychedelic use. In the first case, a man who developed microsmia after a respiratory infection experienced improvement in smell after the use of 6 g of psilocybin containing mushrooms. In the second case, a woman with anosmia since childhood reported olfactory improvement after ingestion of 100 µg of lysergic acid diethylamide (LSD). In the third case, a woman with COVID-19-related anosmia reported olfactory improvement after microdosing 0.1 g of psilocybin mushrooms three times. Following a discussion of these cases, we explore potential mechanisms for psychedelic-facilitated improvement in olfactory impairment, including serotonergic effects, increased neuroplasticity, and anti-inflammatory effects. Given the need for novel treatments for olfactory dysfunction, increasing reports describing improvement in these conditions following psychedelic use and potential biological plausibility, we believe that the possible therapeutic benefits of psychedelics for these conditions deserve further investigation.

Taste and smell alterations affect nutritional status in children under chemotherapy.

AIM: This study aimed to evaluate the incidence of self-reported taste and smell alterations (TSA) in cancer paediatric patients and evaluate the impact of TSA on nutritional status in this population. We also developed and validated a composite score to detect TSA in children undergoing chemotherapy. METHODS: Paediatric patients who were undergoing chemotherapy in a paediatric oncology unit were included. TSA were assessed from the Gustonco questionnaire from which a composite score was developed and internally validated, eating behaviour was assessed using Child Eating Behaviour Questionnaire, and major weight loss was defined from nutritional status. All data were calculated at 1, 3 and 6 months after chemotherapy start. Associations between nutritional status and scores were studied by using logistic models. RESULTS: Among 49 patients included, TSA occurred in 71.7% of patients at 1 month after chemotherapy start and persisted at 3 and 6 months. TSA led to altered appetite since 1 month after chemotherapy start. The occurrence of a major weight loss at 6 months seemed to be associated with a high Gustonco score. CONCLUSION: Taste and smell alterations often occurred in paediatric cancer patients after chemotherapy start and seemed to be associated with impaired nutrition at 6 months after chemotherapy.

Drug-induced olfactory and gustatory dysfunction: Analysis of FDA adverse events reporting system.

OBJECTIVES: With the COVID-19 pandemic, there is growing interest and research in olfactory and gustatory dysfunction (OGD). Drug-induced dysfunction is an often overlooked etiology. While several medications include smell or taste disturbance as a side effect, there are no publications describing which medications are most frequently implicated. We aim to describe the patterns of these adverse drug reactions (ADRs) using the FDA Adverse Events Reporting System (FAERS). METHODS: The FAERS database was queried from 2011 to 2021 for terms describing ADRs related to OGD. Terms included anosmia, hyposmia, olfactory test abnormal, olfactory nerve disorder, hallucination olfactory, parosmia, ageusia, hypogeusia, dysgeusia, and taste disorder. We identified the top reported medications associated with general smell dysfunction, general taste dysfunction, reduced smell, and altered smell. RESULTS: From 2011 to 2021, 16,091 ADRs were reported with OGD, of which13,641 (84.8%) and 2,450 (15.2%) were associated with gustatory and olfactory reactions, respectively. Zinc products (370 reports) and fluticasone propionate (214) were most commonly associated with olfactory dysfunction, specifically reduced olfaction. Varenicline (24) and fluticasone propionate (23) were most commonly associated with altered smell. Lenalidomide (490) and sunitinib (468) were most commonly associated with gustatory dysfunction. Antineoplastic and immunomodulating medications accounted for 21.6% and 36.3% of olfactory and gustatory ADRs, respectively. Among this category, immunoglobulin drugs were the most commonly associated with OGD ADRs. CONCLUSION: Gustatory dysfunction is more commonly reported ADR compared with olfactory dysfunction. Immunologic/rheumatologic medications are the leading culprit of reported OGD. With increasing numbers of patients presenting to otolaryngologists for OGD, it is important to consider drug-induced etiology. LEVEL OF EVIDENCE: III.

Lipopolysaccharide-Initiated Rhinosinusitis Causes Neuroinflammation and Olfactory Dysfunction in Mice.

BACKGROUND: Olfactory dysfunction is a common disease and it may be caused by sinonasal inflammation, toxin inhalation, or neurological disorders. After sinonasal inflammation, if both olfactory neuroinflammation and olfactory dysfunction occur still under investigation. OBJECTIVE: This study aimed to investigate whether neuroinflammation and olfactory dysfunction occur after lipopolysaccharide (LPS)-initiated rhinosinusitis. METHODS: Adult C57BL/6 mice were intranasally administered with LPS for 3 weeks. The olfactory function was evaluated with a buried food test. The inflammatory status of sinonasal cavity and olfactory bulb was evaluated with histology and biochemistry. RESULTS: After 3-week LPS treatment, mice developed olfactory dysfunction, sinonasal cavity, and olfactory bulb inflammation. LPS-treated mice had greater sinonasal mucosal thickness. Besides, pro-inflammatory interleukin-6, the number of goblet cells and neutrophils in the sinonasal cavity was increased after LPS administration. The olfactory sensory neurons in the olfactory epithelium and the olfactory bulb were decreased, and the olfactory function was impaired by LPS administration. Inflammatory cytokines such as interferon-γ and tumor necrosis factor-α were increased in the olfactory bulb. CONCLUSION: This study showed that LPS-initiated rhinosinusitis caused olfactory neuroinflammation and olfactory dysfunction in mice.

Prednisolone does not improve olfactory function after COVID-19: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Prednisolone has been suggested as a treatment for olfactory disorders after COVID-19, but evidence is scarce. Hence, we aimed to determine the efficacy of a short oral prednisolone treatment on patients with persistent olfactory disorders after COVID-19. METHODS: We performed a randomized, double-blind, placebo-controlled, single-centered trial in the Netherlands. Patients were included if they were > 18 years old and if they had persistent (> 4 weeks) olfactory disorders within 12 weeks after a confirmed COVID-19 test. The treatment group received oral prednisolone 40 mg once daily for 10 days and the placebo group received matching placebo. In addition, all patients performed olfactory training. The primary outcome was the objective olfactory function on Sniffin' Sticks Test (SST) 12 weeks after the start of treatment, measured in Threshold-Discrimination-Identification (TDI) score. Secondary outcomes were objective gustatory function assessed by the Taste Strip Test (TST) and subjective self-reported outcomes on questionnaires about olfactory, gustatory and trigeminal function, quality of life, and nasal symptoms. The CONSORT 2010 guideline was performed. RESULTS: Between November 2021 and February 2022, we included 115 eligible patients, randomly assigned to the treatment (n = 58) or placebo group (n = 57). No difference in olfactory function between groups was obtained after 12 weeks. Median TDI score on SST was 26.8 (IQR 23.6-29.3) in the placebo group and 28.8 (IQR 24.0-30.9) in the prednisolone group, with a median difference of 2.0 (95% CI 0.75 to 1.5). There was similar improvement on olfactory function in both groups after 12 weeks. Furthermore, on secondary outcomes, we obtained no differences between groups. CONCLUSIONS: This trial shows that prednisolone does not improve olfactory function after COVID-19. Therefore, we recommend not prescribing prednisolone for patients with persistent olfactory disorders after COVID-19. TRIAL REGISTRATION: This trial is registered on the ISRCTN registry with trial ID ISRCTN70794078.

Taste Impairments in a Parkinson's Disease Model Featuring Intranasal Rotenone Administration in Mice.

BACKGROUND: Taste impairments are often accompanied by olfactory impairments in the early stage of Parkinson's disease (PD). The development of animal models is required to elucidate the mechanisms underlying taste impairments in PD. OBJECTIVE: This study was conducted to clarify whether the intranasal administration of rotenone causes taste impairments prior to motor deficits in mice. METHODS: Rotenone was administrated to the right nose of mice once a day for 1 or 4 week(s). In the 1-week group, taste, olfactory, and motor function was assessed before and after a 1-week recovery period following the rotenone administration. Motor function was also continuously examined in the 4-weeks group from 0 to 5 weeks. After a behavioral test, the number of catecholamine neurons (CA-Nos) was counted in the regions responsible for taste, olfactory, and motor function. RESULTS: taste and olfactory impairments were simultaneously observed without locomotor impairments in the 1-week group. The CA-Nos was significantly reduced in the olfactory bulb and nucleus of the solitary tract. In the 4-week group, locomotor impairments were observed from the third week, and a significant reduction in the CA-Nos was observed in the substantia nigra (SN) and ventral tegmental area (VTA) at the fifth week along with the weight loss. CONCLUSION: The intranasal administration of rotenone caused chemosensory and motor impairments in an administration time-period dependent manner. Since chemosensory impairments were expressed prior to the locomotor impairments followed by SN/VTA CA neurons loss, this rotenone administration model may contribute to the clarification of the prodromal symptoms of PD.

Lactoferrin supplementation for taste and smell abnormalities among patients receiving cancer chemotherapy.

PURPOSE: Taste and smell abnormalities (TSA) are common in patients receiving chemotherapy and may lead to altered nutritional intake, treatment withdrawal, and impaired quality of life. Lipid peroxidation in the oral cavity is one cause of TSA. Lactoferrin (LFN), an iron-binding salivary protein, reduces production of lipid oxidation byproducts and has been shown to reduce perception of unpleasant flavors. To assess the feasibility of LFN as a treatment for TSA, we conducted pilot investigations among patients with cancer who self-reported TSA following onset of chemotherapy. The primary objective was to assess change in subjective taste and smell perception from baseline to completion of 30 days of LFN supplementation. METHODS: Patients were treated with 750 mg LFN daily for 30 days and followed for an additional 30 days without LFN. TSA was measured via the taste and smell questionnaire (TSQ) including taste (score 0-10), smell (score 0-6), and composite scores (0-16) (0 = no TSA) at baseline, day 30, and day 60. RESULTS: A total of 26 patients enrolled; 19 remained on study at day 30 and 17 at day 60. Baseline mean TSQ scores were 6.5 (taste), 3.1 (smell), and 9.6 (composite). By day 30, mean composite TSQ score improved by 1.7 (p = 0.018); taste and smell improved by 0.6 (p = 0.062) and 1.1 (p = 0.042), respectively. From baseline to day 60, mean composite TSQ score improved by 3.8 (p < 0.0001); taste and smell improved by 1.9 (p = 0.001) and 1.8 (p = 0.003). CONCLUSIONS: Further evaluation of LFN is warranted to determine its value for improving self-reported TSA among patients receiving chemotherapy.

The influence of olfactory dysfunction on risk of malnutrition is mediated by depressive symptoms in cancer patients undergoing chemotherapy.

BACKGROUND: Malnutrition is common and detrimental in cancer patients undergoing chemotherapy. There are close associations between olfactory dysfunction, depression, and malnutrition, but how they correlate in cancer patients undergoing chemotherapy remains unclear. METHODS: Two hundred and one cancer patients undergoing chemotherapy were recruited to this study. Their risk of malnutrition was assessed using the Simplified Nutritional Appetite Questionnaire (SNAQ); odor identification was assessed by Sniffin' Sticks test; self-measurement of olfaction was assessed by Self-reported Mini Olfactory Questionnaire (Self-MOQ); and depressive symptoms were assessed using the Beck Depression Inventory (BDI). Correlation analyses and mediation analyses were used to explore the relationships between olfaction, depression, and risk of malnutrition. RESULTS: The SNAQ score was negatively correlated with the Self-MOQ score and BDI score, and positively correlated with body mass index (BMI) scores and odor identification. The Self-MOQ score was negatively correlated with odor identification and positively correlated with BDI scores, and the duration of chemotherapy was negatively correlated with odor identification. Mediation analyses suggested that BDI scores exhibited a partial mediation effect on the relationship between Self-MOQ score and SNAQ scores. CONCLUSIONS: The influence of olfactory dysfunction on risk of malnutrition is mediated by depressive symptoms in cancer patients undergoing chemotherapy. Early intervention of olfactory dysfunction and depressive symptoms may be helpful in reducing the risk malnutrition in cancer patients undergoing chemotherapy.

Effect of Esketamine Nasal Spray on Olfactory Function and Nasal Tolerability in Patients with Treatment-Resistant Depression: Results from Four Multicenter, Randomized, Double-Blind, Placebo-Controlled, Phase III Studies.

BACKGROUND: Intranasal drug delivery offers a non-invasive and convenient dosing option for patients and physicians, especially for conditions requiring chronic/repeated-treatment administration. However, in some cases such delivery may be harmful to nasal and olfactory epithelia. OBJECTIVE: The aim of this study was to assess the potential impact of long-term intermittent treatment with esketamine nasal spray, taken in conjunction with an oral antidepressant (AD), on olfactory function and nasal tolerability in patients with treatment-resistant depression (TRD). METHODS: A total of 1142 patients with TRD participated from four multicenter, randomized, double-blind, phase III studies: three short-term studies (two in patients aged 18-64 years, one in patients ≥65 years), and one long-term maintenance study of esketamine nasal spray + AD versus placebo nasal spray + AD. Across the four studies, assessments were performed at 208 sites in 21 countries. Olfactory function was measured using the 40-item University of Pennsylvania Smell Identification Test (UPSIT®) and the single-staircase Snap & Sniff® Odor Detection Threshold Test (S&S-T). Nasal tolerability, including nasal examinations and a quantitative, self-administered nasal symptom questionnaire (NSQ), was also assessed. Data were analyzed using analyses of covariance. RESULTS: Of 1142 participants, 734 were women (64.3%). The mean age of all participants ranged from 45.7 to 70.0 years across the studies. Overall, 855 patients received esketamine nasal spray + AD and 432 received placebo nasal spray + AD. Objective evaluation of nasal function showed no evidence of an adverse impact following esketamine administration. Based on the UPSIT® and S&S-T results, intranasal administration of esketamine had no effect on the odor identification or threshold test scores compared with placebo nasal spray + oral AD. Similarly, repeated administration with esketamine nasal spray had no meaningful impact on assessments of nasal function. No dose-response relationship was observed between esketamine doses and the olfactory test scores. Esketamine nasal spray was well tolerated, as indicated by responses on the NSQ and negative nasal examination findings. CONCLUSION: Findings from this analysis indicate that there was no evidence of adverse effect on either olfactory or nasal health measures with repeated intermittent administration of esketamine nasal spray at any dose over the course of short-term (4 weeks) or long-term (16-100 weeks) studies. CLINICAL TRIAL REGISTRATION: TRANSFORM-1: NCT02417064, date of registration: 15/04/2015; TRANSFORM-2: NCT02418585, date of registration: 16/04/2015; TRANSFORM-3: NCT02422186, date of registration: 21/04/2015; SUSTAIN-1: NCT02493868, date of registration: 10/07/2015.

Evaluation of antibiotic-induced taste and smell disorders using the FDA adverse event reporting system database.

Adverse effects can occur owing to anorexia, which can reduce treatment compliance and worsen the patients overall condition. One such side effect, namely drug-induced taste and smell disorders, reduces patients quality of life. Although antibiotics can cause taste and smell disorders, a few studies have examined antibiotic-induced taste and smell disorders. Therefore, this study comprehensively analyzed the relationship between taste and smell disorders and antibiotic usage. The side effects of antibiotics were investigated using the FDA Adverse Event Reporting System database (FAERS). The reporting odds ratios between the listed drugs and taste and smell disorders P values were comprehensively calculated. Adjusted odds ratios were calculated to account for patient background. Furthermore, to clarify the feature of this adverse effect, shape parameters indicating the expression pattern were calculated. Signals that induced taste and smell disorders were detected for six antibiotics, including drugs for which this event is not described in the package insert in Japan. Multiple logistic regression analysis suggested an association of taste and smell disorders with gender, hypertension, mental disorder, and cancer. The median time to onset of antibiotic-induced taste and smell disorders was 2-5 days. Six antibiotics could be analyzed, and four of these drugs matched those with detected signals. Our study supported previous findings on gender and age. Furthermore, antibiotic-induced taste and smell disorders are likely to develop in the early stage of treatment. For these reasons, it is important to remember the risk of developing of taste and smell disorders when administering antibiotics. In addition, it is recommended that the patient be monitored carefully for at least 1 week before initiating treatment, and the patients course should be followed for at least 2 months.

Activation of cholinergic system partially rescues olfactory dysfunction-induced learning and memory deficit in mice.

Deficits in olfaction are associated with neurodegenerative disorders such as Alzheimer's disease. A recent study reported that intranasal zinc sulfate (ZnSO4)-treated mice show olfaction and memory deficits. However, it remains unknown whether olfaction deficit-induced learning and memory impairment is associated with the cholinergic system in the brain. In this study, we evaluated olfactory function by the buried food find test, and learning and memory function by the Y-maze and passive avoidance tests in ZnSO4-treated mice. The expression of choline acetyltransferase (ChAT) protein in the olfactory bulb (OB), prefrontal cortex, hippocampus, and amygdala was assessed by western blotting. Moreover, we observed the effect of the acetylcholinesterase inhibitor physostigmine on ZnSO4-induced learning and memory deficits. We found that intranasal ZnSO4-treated mice exhibited olfactory dysfunction, while this change was recovered on day 14 after treatment. Both short-term and long-term learning and memory were impaired on days 4 and 7 after treatment with ZnSO4, whereas the former, but not the latter, was recovered on day 14 after treatment. A significant correlation was observed between olfactory function and short-term memory, but not long-term memory. Treatment with ZnSO4 decreased the ChAT level in the OB on day 4, and increased and decreased the ChAT levels in the OB and hippocampus on day 7, respectively. Physostigmine improved the ZnSO4-induced deficit in short-term, but not long-term, memory. Taken together, the present results suggest that short-term memory may be closely associated with olfactory function via the cholinergic system.

COVID-19-Induced Anosmia and Ageusia Are Associated With Younger Age and Lower Blood Eosinophil Counts.

BACKGROUND: Anosmia and ageusia are symptoms commonly associated with COVID-19, but the relationship with disease severity, onset and recovery are unclear. OBJECTIVE: To examine factors associated with anosmia and ageusia and the recovery from these symptoms in an ethnically diverse cohort. METHODS: Individuals tested for SARS-CoV-2 between March and April 2020 were eligible for the study. Randomly selected participants answered a telephone questionnaire on COVID-19 symptoms with a focus on anosmia and ageusia. Additionally, relevant past medical history and data on the COVID-19 clinical course were obtained from electronic medical records. 486 patients were in the COVID-19 group and 103 were COVID-19-negative. RESULTS: Patients who were younger were more likely to report anosmia and/or ageusia (odds ratio (OR) for anosmia per 1-year increase in age: 0·98, 95%CI:0-97-0·99, p = 0·003; for ageusia: 0·98, 95%CI:0·97-0·99, p = 0·005) as were patients with lower eosinophil counts (OR for anosmia per 0.1-K/µL increase in eosinophils: 0·02, 95%CI:0·001-0·46, p = 0·01, for ageusia 0·10, 95%CI:0·01-0·97, p = 0·047). Male gender was independently associated with a lower probability of ageusia (OR:0·56, 95%CI:0·38-0·82, p = 0·003) and earlier sense of taste recovery (HR:1·44, 95%CI:1·05-1·98, p = 0·02). Latinos showed earlier sense of taste recovery than white patients (HR:1·82, 95%CI:1·05-3·18, p = 0·03). CONCLUSION: Anosmia and ageusia were more common among younger patients and those with lower blood eosinophil counts. Ageusia was less commonly reported among men, and time to taste recovery was earlier among both men and Latinos.

Alterations in Piriform and Bulbar Activity/Excitability/Coupling Upon Amyloid-ß Administration in vivo Related to Olfactory Dysfunction.

BACKGROUND: Deficits in odor detection and discrimination are premature symptoms of Alzheimer's disease (AD) that correlate with pathological signs in the olfactory bulb (OB) and piriform cortex (PCx). Similar olfactory dysfunction has been characterized in AD transgenic mice that overproduce amyloid-ß peptide (Aß), which can be prevented by reducing Aß levels by immunological and pharmacological means, suggesting that olfactory dysfunction depends on Aß accumulation and Aß-driven alterations in the OB and/or PCx, as well as on their activation. However, this possibility needs further exploration. OBJECTIVE: To characterize the effects of Aß on OB and PCx excitability/coupling and on olfaction. METHODS: Aß oligomerized solution (containing oligomers, monomers, and protofibrils) or its vehicle were intracerebroventricularlly injected two weeks before OB and PCx excitability and synchrony were evaluated through field recordings in vivo and in brain slices. Synaptic transmission from the OB to the PCx was also evaluated in slices. Olfaction was assessed through the habituation/dishabituation test. RESULTS: Aß did not affect lateral olfactory tract transmission into the PCx but reduced odor habituation and cross-habituation. This olfactory dysfunction was related to a reduction of PCx and OB network activity power in vivo. Moreover, the coherence between PCx-OB activities was also reduced by Aß. Finally, Aß treatment exacerbated the 4-aminopyridine-induced excitation in the PCx in slices. CONCLUSION: Our results show that Aß-induced olfactory dysfunction involves a complex set of pathological changes at different levels of the olfactory pathway including alterations in PCx excitability and its coupling with the OB. These pathological changes might contribute to hyposmia in AD.

Paraquat Inhalation, a Translationally Relevant Route of Exposure: Disposition to the Brain and Male-Specific Olfactory Impairment in Mice.

Epidemiological and experimental studies have associated oral and systemic exposures to the herbicide paraquat (PQ) with Parkinson's disease. Despite recognition that airborne particles and solutes can be directly translocated to the brain via olfactory neurons, the potential for inhaled PQ to cause olfactory impairment has not been investigated. This study sought to determine if prolonged low-dose inhalation exposure to PQ would lead to disposition to the brain and olfactory impairment, a prodromal feature of Parkinson's disease. Adult male and female C57BL/6J mice were exposed to PQ aerosols in a whole-body inhalation chamber for 4 h/day, 5 days/week for 4 weeks. Subsets of mice were sacrificed during and after exposure and PQ concentrations in various brain regions (olfactory bulb, striatum, midbrain, and cerebellum) lung, and kidney were quantified via mass spectrometry. Alterations in olfaction were examined using an olfactory discrimination paradigm. PQ inhalation resulted in an appreciable burden in all examined brain regions, with the highest burden observed in the olfactory bulb, consistent with nasal olfactory uptake. PQ was also detected in the lung and kidney, yet PQ levels in all tissues returned to control values within 4 weeks post exposure. PQ inhalation caused persistent male-specific deficits in olfactory discrimination. No effects were observed in females. These data support the importance of route of exposure in determination of safety estimates for neurotoxic pesticides, such as PQ. Accurate estimation of the relationship between exposure and internal dose is critical for risk assessment and public health protection.

Chemotherapy-induced taste and smell changes influence food perception in cancer patients.

PURPOSE: Chemotherapy-induced taste and smell alterations may have a negative impact on the quality of life and nutritional status. A prominent issue when dealing with taste and smell alterations and their consequences on food behavior and well-being lies in the variation arising from individual differences in chemosensory perceptions. The main aim of this study was to examine the effect of individuals' variation in the severity of taste and smell alterations relative to the stage of chemotherapy on self-reported food behavior and food perception. METHODS: Eighty-nine cancer patients completed a questionnaire subdivided into two parts: a chemosensory part that allowed classification of patients in three groups ("no alterations," "moderate alterations," and "severe alterations") and a food behavior part. RESULTS: The results highlighted a negative impact of chemosensory alterations on food perception. Compared with patients without taste and smell alterations, patients with severe chemosensory alterations reported significantly more frequent food perception problems, including modification of the perceived taste of food, finding bad taste in all food, and being unable to perceive food taste. Whereas 72% of patients with severe alterations were in late stage, only 37% of patients were in late stage in the no alterations group, indicating an effect of the treatment stage on taste and smell alterations. CONCLUSION: Our results underlie the importance of providing specific attention to the severity of chemotherapy-induced taste and smell alterations and considering the individual differences among patients for a better nutritional management.