The Covid-19 epidemic has led to the discovery that anosmia – the loss of the sense of smell – is a disorder whose consequences can be more serious than commonly imagined.
- Anosmia, or loss of smell, would affect a majority of Covid-19 patients
- This loss of smell previously only affected 5% of the population and was not considered by the general public to be a serious illness.
- Anosmia is however a real handicap which disrupts food intake and represents an important gene in daily life.
This is one of the most common symptoms of Covid-19: anosmia would temporarily affect between 60 and 80% of people infected with the coronavirus. And yet, this loss of smell covered by the “scholarly” name of anosmia was not, until then, a disorder that we cared much about. “Olfaction is a sense that is poorly considered, people have the impression that their sense of smell is not something very important, for the general public, anosmia is not very serious, it is not is not as if we were blind”, remarks Dr. Claire Martin, neurobiologist, who notes what this lack of interest is paradoxical in a country like France, champion of perfumery and… of great cuisine!
Loss of sense of smell is very disabling
All those who have suffered from it or who continue to suffer from it after being infected with SARS-CoV-2 have certainly changed their minds. “When we talk to people who have experienced this loss of smell, and there are more and more of them since the start of the epidemic, we can see that it is something that is very disabling”, underlines Claire Martin. The loss, even temporary, of this sense has a particular impact on food intake since the sense of smell largely contributes to taste, with which it is closely linked. But it also disrupts non-verbal communication and, above all, can be the cause of domestic accidents by preventing recognition of odors signaling a danger, fire or the presence of toxic products, for example.
While cases of anosmia have multiplied with the Covid-19 epidemic, this disorder has until then only affected around 5% of the population. Among the most classic causes, genetics – the absence of smell can be hereditary -, certain infectious rhinitis, nasal polyposis, minor head trauma but especially neurodegenerative diseases such as Alzheimer’s or Parkinson’s.
The sense of smell can be re-educated
Fortunately, even if a certain proportion of Covid-19 patients are likely to suffer from this loss of smell for many months, the anosmia due to the epidemic only lasts for most patients two or three weeks. “We think that 90% of those affected recover their sense of smell anyway after 6 or 8 months at most”, specifies Claire Martin.
The good news is that while there is no drug treatment to “cure” anosmia, smell is a sense that can be retrained. “The advantage of the olfactory system is that the neurons which are in the nose and which detect odors can grow back”, explains the neurobiologist, recalling that there is a rehabilitation protocol which lasts 12 weeks and which is based on exercises using essential oils to stimulate these neurons and olfactory memory. “Studies show that this technique brings benefits for about 30% of those who practice it,” says Claire Martin.
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