Going viral: What Covid-19-related loss of smell reveals about how the mind works (original) (raw)
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Olfactory dysfunction: A plausible source of COVID-19-induced neuropsychiatric symptoms
Frontiers in Neuroscience, 2023
Olfactory dysfunction and neuropsychiatric symptoms are commonly reported by patients of coronavirus disease 2019 (COVID-19), a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence from recent research suggests linkages between altered or loss of smell and neuropsychiatric symptoms after infection with the coronavirus. Systemic inflammation and ischemic injury are believed to be the major cause of COVID-19-related CNS manifestation. Yet, some evidence suggest a neurotropic property of SARS-CoV-2. This mini-review article summarizes the neural correlates of olfaction and discusses the potential of trans-neuronal transmission of SARS-CoV-2 or its particles within the olfactory connections in the brain. The impact of the dysfunction in the olfactory network on the neuropsychiatric symptoms associated with COVID-19 will also be discussed.
Chemical Senses, 2021
In a preregistered, cross-sectional study we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0-100 visual analog scales (VAS) for participants reporting a positive (C19+; n=4148) or negative (C19-; n=546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19- groups exhibited smell loss, but it was significantly larger in C19+ participants (mean±SD, C19+: -82.5±27.2 points; C19-: -59.8±37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC=0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more pre...
Olfactory Dysfunction in Frontline Health Care Professionals During COVID-19 Pandemic in Brazil
Frontiers in Physiology, 2021
Upper respiratory viral infections can decrease the sense of smell either by inflammatory restriction of nasal airflow that carries the odorant molecules or through interference in olfactory sensory neuron function. During the coronavirus disease 2019 (COVID-19) pandemic, triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), worldwide reports of severe smell loss (anosmia/hyposmia) revealed a different type of olfactory dysfunction associated with respiratory virus infection. Since self-reported perception of smell is subjective and SARS-CoV-2 exposure is variable in the general population, we aimed to study a population that would be more homogeneously exposed to the virus. Here, we investigated the prevalence of olfactory loss in frontline health professionals diagnosed with COVID-19 in Brazil, one of the major epicenters of the disease. We also analyzed the rate of olfactory function recovery and the particular characteristics of olfactory deficit in this pop...
How COVID-19 brought smell disorders in the spotlight
Romanian Journal of Rhinology
The rapid spread of the COVID-19 infection required prompt recognition and immediate isolation of patients. In the evolution of the disease various symptoms were indicated as suggestive of a SARS-CoV-2 infection, among them being also described anosmia and ageusia. In order to review how olfactory disorders are related to COVID-19 disease, we carried out an analysis by searching PubMed, Science Direct, Springer, and LILACS. The research was made using MeSH descriptors and the Boolean operator, “AND”, for the terms “olfactory disorders” or “olfactory dysfunction” or “anosmia” or “neurologic manifestations” or “ENT symptoms” AND “COVID-19” or “SARS-CoV-2” or “coronavirus infections”, with a filter on the publication date set for 01.01.2020 – 18.06.2021. A total of 956 articles were found in the databases, out of which 14 were included in the study. The statistics suggest that alterations of the chemosensory function are strongly correlated with COVID-19, although the exact pathophysio...
Six month follow-up of self-reported loss of smell during the COVID-19 pandemic
Rhinology journal, 2020
INTRODUCTION: Loss of smell and taste is now recognised as amongst the most common symptoms of COVID-19 and the best predictor of COVID-19 positivity. Long term outcomes are unknown. This study aims to investigate recovery of loss of smell and the prevalence of parosmia. METHODOLOGY: 6-month follow-up of respondents to an online surgery who self-reported loss of smell at the onset of the CO- VID-19 pandemic in the UK. Information of additional symptoms, recovery of loss of smell and the development of parosmia was collected. RESULTS: 44% of respondents reported at least one other ongoing symptom at 6 months, of which fatigue (n=106) was the most prevalent. There was a significant improvement in self-rating of severity of olfactory loss where 177 patients stated they had a normal smell of smell while 12 patients reported complete loss of smell. The prevalence of parosmia is 43.1% with median interval of 2.5 months (range 0-6) from the onset of loss of smell. CONCLUSIONS: While many p...
Open Forum Infectious Diseases
Background Clinical diagnosis of coronavirus disease 2019 (COVID-19) is essential to the detection and prevention of COVID-19. Sudden onset of loss of taste and smell is a hallmark of COVID-19, and optimal ways for including these symptoms in the screening of patients and distinguishing COVID-19 from other acute viral diseases should be established. Methods We performed a case–control study of patients who were polymerase chain reaction–tested for COVID-19 (112 positive and 112 negative participants), recruited during the first wave (March 2020–May 2020) of the COVID-19 pandemic in Israel. Patients reported their symptoms and medical history by phone and rated their olfactory and gustatory abilities before and during their illness on a 1–10 scale. Results Changes in smell and taste occurred in 68% (95% CI, 60%–76%) and 72% (95% CI, 64%–80%) of positive patients, with odds ratios of 24 (range, 11–53) and 12 (range, 6–23), respectively. The ability to smell was decreased by 0.5 ± 1.5...
High prevalence of long-term psychophysical olfactory dysfunction in patients with COVID-19
2021
This study prospectively assessed the long-term prevalence of self-reported and psychophysically measured olfactory dysfunction in subjects with mild-to-moderate COVID-19. Self-reported smell or taste impairment was prospectively evaluated by SNOT-22 at diagnosis, 4-week, 8-week, and 6-month. At 6 months from the diagnosis, psychophysical evaluation of olfactory function was also performed using the 34-item culturally adapted University of Pennsylvania Smell Identification Test (CA-UPSIT). 145 completed both the 6-month subjective and psychophysical olfactory evaluation. According to CA-UPSIT, 87 subjects (60.0%) exhibited some smell dysfunction, with 54 (37.2) being mildly microsmic, 16 (11.0%) moderately microsmic, 7 (4.8%) severely microsmic, and 10 patients (6.9%) being anosmic. At the time CA-UPSIT was administered, a weak correlation was observed between the self-reported alteration of sense of smell or taste and olfactory test scores (Spearman r=-0.26). Among 112 patients who...
Viral infection and smell loss: The case of COVID‐19
Journal of Neurochemistry, 2020
Olfactory disorders have been increasingly reported in individuals infected with SARS-CoV-2, the virus causing the coronavirus disease 2019 (COVID-19). Losing the sense of smell has a strong impact on the quality of life, since it may lead to malnutrition, weight loss, food poisoning, depression, and exposure to dangerous chemicals. Individuals who suffer from anosmia (inability to smell) also cannot sense the flavor of food, which is a combination of taste and smell. Interestingly, infected individuals have reported sudden loss of smell with no congested nose, as is frequently observed in common colds or other upper respiratory tract infections. These observations suggest that SARS-CoV-2 infection leads to olfactory loss through a distinct mechanism, which is still unclear. This article provides an overview of olfactory loss and the recent findings relating to COVID-19. Possible mechanisms of SARS-CoV-2-induced olfactory loss are also discussed.