Loss of smell after Covid: what causes researchers are on the track

A completely new study by Columbia University in New York has now come to the conclusion that the nerve cells are intact, but have fewer receptors to recognize taste molecules.

Why one suffers a loss of smell and the other does not could be due to a recently discovered special genetic mutation lie: It leads to the formation of proteins that remove odor molecules from the nose as soon as they are detected. But how the coronavirus interacts with these genes and how it apparently activates these proteins is still unclear.

There is also evidence of persistent changes in brain structure in people with smell loss. 785 people in the UK had two brain scans spaced apart. 400 fell ill with Covid-19 between the two dates. The researchers were able to detect various changes in the structure of the brain in these people, including in the olfactory center. The reason for this is not clear, but the lack of olfactory sensation could be a cause. “When the nose gets less input, the brain degrades,” says geneticist Danielle Redd of the Monell Center in Philadelphia.

Hope for new therapies

The main therapy currently is smell training with different scents. However, “This method only seems to work for people with a partial loss of smell,” says Reed.

For the others, people are still looking for effective therapies: One hope was nasal sprays containing cortisone to relieve inflammation. Inflammation caused by Covid-19 could at least be a contributing factor in the loss of smell. previous studies but showed no positive effect.

Another approach could be blood plasma enriched with blood platelets (thrombocytes), which is obtained from the respective patients. small studies showed improvements in the sense of smell in some of the participants when the plasma was injected into the nose. So far, the number of participants is too small, larger studies are in progress. Another approach could be vitamin A, here there are first indications of a certain effectiveness in other forms of odor loss.

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