A key and worrying symptom of Covid-19, the loss of smell has become rarer with the Omicron variant. According to one norwegian study published in the journal Eurosurveillance in January 2022, the loss of smell represented only 12% of cases of the last variant of Covid-19.
If the loss of smell now concerns only a minority of people, others are unable to regain their sense of smell, several months after infection. “In 85% of cases, patients recover their sense of smell after 4 to 6 weeks, the fastest after about ten daysexplains Jean-Marie Lledo, head of the Olfactory Perception and Memory Unit at the Institut Pasteur and research director at the CNRS. But in the remaining 15%, some regain their sense of smell after several months and others still have not found it..” Periods of anosmia which can last up to nine monthssee more.
And these long periods without being able to feel are not without consequences. “We have known for a long time, long before the Covid-19 pandemic, that the olfactory system is related to the circuits that manage our emotions.“, says the researcher. Throughout our lives, we are exposed to odors, and “even before identifying them, we know what we like and what we don’t like“. However, the Covid-19 can affect neurons of the olfactory systemmake them defective and therefore significantly alter our emotions.
Loss of sense of smell leads to loss of bearings
So, the relationship between smell and emotion is very close. And when we are deprived of our sense of smell, it will directly disturb our emotions, and even more when it lasts over time. “In humans, the loss of the sense of smell leads to loss of bearingscompared to what he already knowssays Jean-Marie Lledo. It’s like putting him in a new world.”
After this loss of bearings, the loss of smell will activate a profound loss of self-confidence. Without smell, we use less cosmetics or perfumes, we less attention to oneself and this is reflected in our connections with the outside world. “Our sense of smell is what forges our privileged relationship with the world. Without smell, more confidence and therefore more relationship with the other“, he continues.
And some consequences can be serious and are not to be underestimated. “These long-term Covid patients with long-term loss of smell will be affected by mood disorders: olfactory disorders will be associated with a depressed statenoted by psychiatrists, and cognitive complaints“, says the researcher.
Impact on daily quality of life
When we lose our sense of smell, food, which punctuates our days, loses all its importance. “When you savor a dish, taste a wine or drink a coffee, 80% or more of the aromas come directly from the nose“, recalls Pierre-Marie Lledo. With anosmia, they disappear and we will no longer tend to neglecting one’s food.
The researcher even proposes an experiment: “Take a candy for example. If you eat it holding your nose, you will first smell the gelatinous texture, then as soon as you open your nostrils, the smell comes back..” With anosmia it’s the same, except that the smell does not return for a few months, in the worst case.
Another disturbing fact of this long-term loss of smell is that all the alarm signals made possible by smell are unable to function: “TheOlfaction is the sense of alarm. Faced with spoiled meat or rotten fruit inside and without their sense of smell, the patient faces a major health risk.“Warning Pierre-Marie Lledo. Waking up with the smell of smoke or gas, an act that can save our lives is also not possible.
From when to worry?
“After six weeks without smell, it is necessary to consult“, warns the researcher. But the loss of smell is not only specific to Covid-19. “It is one of the first signs of neurological diseases like Alzheimer’s or Parkinson’s“, explains the CNRS research director. If before the pandemic, patients did with the subtle decrease in their sense of smell, this is no longer the case: the Covid-19 has made it a main warning signal.
“We cannot yet explain why some people still do not find their sense of smell after 9 months, this is the question we will try to answer throughout our study.“, explains the researcher. Conducted over two years with patient follow-up for a year, then a year of analyses, the study is only at its beginnings and should reveal the first results in the next six months. FRM websitewhich funds the research project of Professor Pierre-Marie Lledo.
Our speakers:
- Pierre-Marie Lledo, Head of the Perception and Olfactory Memory Unit at the Institut Pasteur and Research Director at the CNRS. He is conducting the studyLong Covid: what neurological and psychiatric risks are associated with long-term loss of smell?”
- The FRM (Foundation for Medical Research) has been involved in the pandemic since March 2020. Today, it continues to mobilize to know the long-term impacts of Covid-19. The FRM has selected four research projects, including that of Professor Pierre-Marie Lledo, to finance them and thus find answers to persistent questions.
Sources:
- Outbreak caused by the SARS-CoV-2 Omicron variant in Norway, November to December 2021, EurosurveillanceJanuary 2022
- Sequelae of Covid-19: 60% of hospitalized patients have at least one symptom after six monthsInserm, May 2021
Read also:
- Loss of smell: no, it’s not necessarily covid!
- Loss of smell and Covid-19: the majority of patients recover after 2 months