Quantitative but not qualitative flavor recognition impairments in COVID-19 patients

Abstract

Background Smell and taste dysfunctions (STDs) are symptoms associated with COVID-19 syndrome, even if their incidence is still uncertain and variable. Aims In this study, the effects of SARS-CoV-2 infection on chemosensory function have been investigated using both a self-reporting questionnaire on smell and flavor perception, and a simplified flavor test. Methods A total of 111 subjects (19 hospitalized [HOS] and 37 home-isolated [HI] COVID-19 patients, and 55 healthy controls [CTRL]) were enrolled in the study. They received a self-evaluation questionnaire and a self-administered flavor test kit. The flavor test used consists in the self-administration of four solutions with a pure olfactory stimulus (coffee), a mixed olfactory-trigeminal stimulus (peppermint), and a complex chemical mixture (banana). Results After SARS-CoV-2 infection, HOS and HI patients reported similar prevalence of STDs, with a significant reduction of both smell and flavor self-estimated perception. The aromas of the flavor test were recognized by HI and HOS COVID-19 patients similarly to CTRL; however, the intensity of the perceived aromas was significantly lower in patients compared to controls. Conclusion Data reported here suggests that a chemosensory impairment is present after SARS-CoV-2 infection, and the modified “flavor test” could be a novel self-administering objective screening test to assess STDs in COVID-19 patients. Clinical trial registration no. NCT04840966; April 12, 2021, retrospectively registered

Olfactory-related quality of life impacts psychological distress in people with COVID-19: The affective implications of olfactory dysfunctions

“…Lower thresholds in odor detection, greater olfactory awareness, and enhanced reactivity to odors have been found in individuals with panic disorder as well ( Burón et al, 2015 ). When compared to non-infected persons, COVID-19 patients can maintain a similar capacity to recognize odors, but the intensity of the perceived odors appears as significantly diminished ( Nettore et al, 2021 ). That is, COVID-19 seems to be associated with impairment of the quantitative features of odor recognition, but not with its qualitative aspects.…”

“…Coronaviruses-related olfactory dysfunctions are caused by the destruction of the olfactory epithelium, whereby odors are impaired from binding to the corresponding receptors ( Murphy et al, 2003 ). Besides the intensification or precipitation of negative mental health outcomes – namely, post-traumatic stress disorder, alcohol abuse, obsessive-compulsive behaviors, anxiety, depression, panic, and paranoia ( Pedrosa et al, 2020 ) – COVID-19-related olfactory dysfunctions are also significantly correlated with psychological distress and affective disorders ( Nettore et al, 2021 ). In addition, smell loss caused by COVID-19 has been shown to negatively impact the individual's QoL, significantly influencing the person's daily activities associated with olfactory functions ( Elkholi et al, 2021 ).…”

Persistent Olfactory and Taste Dysfunction after COVID-19

“…Some patients who have normal taste tests report that they have no problems recognizing basic tastes but have problems identifying different foods. This points to the problem lying more with retronasal olfaction and impaired detection of flavors (which are a mixture of odor and taste compounds), not basic tastes [ 13 , 30 ].…”

“…The second is related to the fact that the perception of taste depends not only on the taste of the food consumed but also on its smell and temperature. Patients with retronasal OD report accompanying GDs [ 12 , 13 ].…”