- At least a third of people who have had COVID and had an olfactory and taste disorder have actually lost some of their ability to perceive basic tastes, say European scientists who have studied the effects of coronavirus infection on both of these senses.
Smell and taste dysfunctions are among the most commonly reported symptoms of COVID-19. A significant proportion of patients still report it after beating the disease. While much evidence points to the effect of coronavirus infection on the sense of smell, few observations mention the direct involvement of the virus in the pathogenesis of dysgeusia.
Data from the University Hospital in Trieste, where patients tested for taste and smell disorders, came to the study. In total, from March 1 to July 31, 2022, a total of 172 patients were referred to the clinic due to chemosensory disorders after COVID-19, of which 110 of them experienced a permanent change related to COVID in the perception of basic tastes.
The analysis excluded people who had ever undergone sinonasal surgery, had neurological and psychiatric disorders, and suffered from an olfactory / taste dysfunction. Both the olfactory function of the nasal cavity and the taste evaluation were measured using validated tests. Psychophysical assessment was carried out on average 226 days after the onset of the disease.
Most of the cases analyzed had mild COVID-19 symptoms, with no symptoms related to pneumonia. Almost all patients self-reported accompanying olfactory disorders.
The study found that more than half of the subjects reporting a change in taste perception showed a normal taste function, while most of them had an olfactory impairment. Importantly, 42 percent. there was hypogeusion, i.e. deterioration of the sense of taste. This, according to researchers, proves that true taste disturbances are also more common than previously thought.
According to the researchers, the taste buds of some participants may have partially lost the ability to distinguish between primary tastes due to the aging process, but even after assessing the results by age, still 29% showed a deterioration of the sense of taste.
The research analysis is associated with certain limitations, which concern, for example, the lack of psychophysical assessment performed in the acute phase of the disease -different patients were scored at different time points. Moreover, the analyzes did not concern the age-matched control group. In addition, the questions asked during the conduct of the research on taste functions, are not the best tools and can be misleading.
The use of one sensory technique to characterize the taste function could give false negative results, as well as other disorders such as parosmia and fantosmia were not included in the study. The project itself was monocentric and participants were mostly female and experienced mildly symptomatic COVID-19, limiting the generalization of the results.
Nevertheless, researchers believe that the issues related to loss of taste and disturbance of this sense were previously a largely overlooked aspect, so they emphasize that while olfactory training can help people suffering from olfactory disorders, strategies to help people with smell disorders are also needed. people with taste disorders.