Among all other symptoms of COVID-19 since its prevalence, patients were affected mostly by TSD, while they were in medication. The recent study tries to give reasons for the loss of smell and taste in COVID-19 patients.
According to the study conducted by researchers at the NYU Grossman School of Medicine and Columbia University, the SARS-CoV-2 virus tends to dial down the action of olfactory receptors in our body.
It even impacts the proteins present on the surfaces of nerve cells in the nose that are responsible for detecting molecules associated with smell, the researchers pointed out.
To get further understanding of it, they studied the molecular consequences of the virus on golden hamsters and some olfactory tissues sourced from human autopsies.
They found that due to the presence of the COVID-19 virus, an inrushing of immune cells, T cells, and microglia was observed near the nerve cells in olfactory tissue. They noticed that these cells release a protein called “cytokines,” which changes the olfactory nerve cells’ genetic activity. Virus infects the supporting cells of the olfactory epithelium, which surround the receptor neurons responsible for the perception of odors.
It was found out that the infection decreased the ability of DNA chains in chromosomes, which are associated with olfactory receptor building through the experiment conducted. In both the hamsters and human neuronal tissues, researchers observed a widespread and persistent downregulation of it.
Previous research suggested that patients were still suffering this deceptively unpleasant symptom six months after recovering from their initial illness. But the newly published findings indicate that the after effects may last even longer for some patients.
Loss of smell and taste is common in diseases caused by respiratory viruses like cold and flu. This is partly because throat and nose swellings can interrupt smell and taste receptors.
These viruses cause damage to small nerves in the nasal passage causing the loss of smelling and taste. As these nerves recover, some patients recover fully in about three to four months and for some patients it may take years to recover.
Some doctors are also exploring whether vitamin A nose drops could help reverse the damage, as per a German study published last April, by taking the drops regularly for eight weeks sped up the recovery by 14% of participants. The recovery process is a matter of time and patience for the most of them.
In another study, researchers conduct an analysis based on the data of a multi-cohort study. The goal of the study was to identify subject characteristics, investigate the relationship between TSD and immune response intensity, and characterize symptom associations for patients with or without TSD.
The study participants were provided with two electronic self-administered questionnaires. They also provided self-sampling dried-blood spot for serology testing to identify patients who were infected with COVID-19.
The symptoms, which were included in this study, were present at least once within 14 days before each questionnaire was reported. And also, data on alcohol consumption, smoking status, and body mass index were also extracted.
Out of the 93,610 participants, 3,439 were included in the study. Out of which 750 were reported TSD, whereas 71.2% of women with a median age of 51 reported TSD, 68.7% with a median age of 46 did not report this symptom. Smoking status, alcohol consumption of at least two drinks a day, and the female sex were associated with a higher probability of TSD. Participants aged 30, 50, 60, or 70 showed a higher probability of TSD as compared to those aged 40.
All serological titers were associated with a higher probability of TSD. Furthermore, in 90% of study participants, TSD was associated with a wide variety of symptoms, while for 10% of the participants, TSD was an isolated symptom or associated with rhinorrhea.
The current study indicates that the chances of developing TSD were higher in women, smokers, and drinkers more than two drinks a day. TSD was also found to induce a strong humoral response, with most cases of TSD associated with a wide variety of symptoms.
The limitations of this study was that humoral immunity can decrease with time and may not be detectable in 10% to 20% of individuals. And the self-reporting of symptoms can introduce bias.
Researchers at the Karolinska Institute in Stockholm ran tests on 100 people who had COVID-19 in 2020 and each of those tested had lost their sense of smell.
After 18 months, one in 20 of the patients still had not regained their smell.
Source: Medindia
Really interesting post!