Researchers from Italy (Trieste) conducted a study entitled “Comprehensive chemosensory psychophysical assessment of self-reported taste dysfunction in patients with long-term COVID-19: a cross-sectional study”. Most patients with COVID-19 self-report dysfunction in smell and taste, making them among the most common symptoms of the disease and most commonly affecting the oral cavity. However, the study found that signs of hypogeusia three months after symptom onset may be significantly less than self-reported.
In a cross-sectional study, researchers from the University of Trieste evaluated 105 COVID-19 recoveries, all of whom self-reported a decrease in their sense of taste and almost all (94.3%) had a decrease in their sense of smell due to COVID-19 infection. The vast majority (98.1%) of patients recovered from the disease with mild symptoms and no evidence of pneumonia. The researchers conducted a psychophysical and psychological assessment of the participants and found that hypogeusia could be confirmed in less than half (41.9%) of them. This figure dropped to 28.6% after the results were adjusted for participants' age.
According to the researchers, self-reported hypogeusia may be due to olfactory dysfunction. The researchers stated: “[Indeed] our study showed that even when patients were specifically asked about basic tastes, more than half of those who reported altered taste perception demonstrated normal gustatory function, while most of them had impaired olfaction.”
The researchers wrote: “[This] psychophysical study reveals an overestimation of self-reported taste disorders and supports the use of validated psychophysical tests to assess chemosensory dysfunction in people with long-term COVID-19.”
Researchers said that while the number of confirmed cases of hypogeusia may be lower than self-report indicates, the condition has been largely ignored so far. “Smell training may help with recovery, and additional strategies may be required for people with taste disorders,” they wrote.