They discover why the Covid-19 leaves them without smell

• Direct Latest news about the coronavirus

Man is not a hunting dog, in our species the

of

is of little or no use. Before the pandemic, we would all have subscribed to this phrase, relegating the human "style" to some kind of evolutionary holdover. We were very wrong: with

, which has among its

most typical

the loss of smell, it has become clear that this sense is not at all secondary and in fact, thanks to the numerous new studies on the subject, it is being discovered that it is an important indicator of our health.

In the first place, because losing it can be a wake-up call for the

infection

, precisely: two research consortiums, the

and

, were born last year precisely to study in detail what happens with the olfactory sense with the infection and from the data collected over months on tens of thousands of people around the world, it seems clear that

are targets of the virus, regardless of the variants.

Olfactory bulb

The effect of the virus on the sense of smell is so clear that, as explained by Sara Spinelli from

(DAGRI) of the University of Florence, which is participating in the research, "the increase in reports of

are it considers a marker of the very early increase in cases and directly related to hospitalizations, as well as an index of the effectiveness of distancing measures: just five days after a confinement the new reported cases of alterations decrease ".

Initially it was thought that the virus attacked olfactory neurons through

Ace-2

, the same ones used to enter other cells;

However, Sandeep Datta, a neurobiologist at Harvard University, discovered that these receptors are not expressed by olfactory neurons, but by other cells that surround them and by stem cells found in the

, necessary to repair the frequent damage to the What are Stem cells.

The olfactory sensory neurons are exposed by being in direct contact with the outside.

Different paths to the cure

Investigators' subtleties?

Quite the opposite because, as Datta explains, "the precise target of the virus can explain why patients who lose their sense of smell have very different healing trajectories. In some, the alteration is only

because only the so-called

have been damaged.

, which act as physical and metabolic support for neurons; in others, the damage is such that neurons die and can reform from stem cells in months, so olfactory abnormalities persist longer; in others, the The virus attack may have affected support cells and stem cells, preventing the growth of new neurons and, therefore, the recovery of olfactory function. "

Wrong smells

Datta's theory would also explain parosmia and phantosmia, that is, situations in which the patient feels that the

- the wine can smell like gasoline, the shampoo musty - or that they do not exist.

Nerve connections altered by the virus are poorly "reconnected" during the repair phase and this would lead to abnormal olfactory signaling pathways.

"According to research, recovery of smell is more or less slow and complete depending on individual characteristics; it is more difficult as the age and severity of the disease increase, but even young people who have had few symptoms can take months to smell again, "says Spinelli.

"However, there is the possibility of helping patients regain their sense of smell, through a process of so-called re-familiarization and kits of different smells to smell to slowly get used to: studies are still ongoing and to date no it is known which protocol guarantees the best results and the time required for full recovery. "

On the other hand, the negative effect of the loss of

on the quality of life and well-being of patients is true, as well as on the

: the areas connected to the perception of odors such as the olfactory bulb or the piriformis.

The cortex is reduced, the same occurs in areas related to rational thinking and movement control, such as the anterior cingulate cortex, or with the processing of emotions, such as the limbic system.

Brain damage

All this happens regardless of the reason that induces the alteration of smell:

is not the only possible cause and, apart from the temporary reduction typical of when we have a cold virus, it is now clear that changes in smell they are an early sign of various diseases that affect the central nervous system.

In fact, if the

to the brain involves olfactory areas, the ability to smell good is attenuated and thus, for example, up to 38% of patients with multiple sclerosis and about half of people diagnosed with dementia have had signs of loss. smell about five years before the onset of neurological symptoms.

In

estimates of olfactory abnormalities even range between 45% and 96% of cases, so much so that a project, Predict-PD, has been launched in the United Kingdom, which by means of a smell test attempts to identify in advance who might be affected by the disease.

"The pandemic is giving new impetus to the creation of tests for smell, but at the moment these are not tests that can be done in five minutes at home, alone," Spinelli specifies.

"Validated tests are long, many samples must be smelled and they must be well interpreted to understand where the sense of smell is 'stuck'. The goal now is to create simpler, faster and cheaper ones that can aid in detection. of

and other pathologies or conditions in which the sense of smell is compromised. For example, it also occurs in many cancer patients who undergo chemotherapy), thanks to nutritional programs that take into account olfactory difficulties. "

Autoimmune diseases

The list of health problems also reported by a decrease in smell is long: it occurs in autoimmune diseases such as rheumatoid arthritis (and there are those who hypothesize unknown infectious causes since many viruses, not only

or those of the cold, olfactory target neurons) but also in depression, the severity of which is directly proportional to the shrinkage of the olfactory bulb.

Even as we

, the sense of smell worsens and after the age of 70, for example, it is estimated that one in five people no longer know how to correctly identify the smell of smoke or gas.

And who knows if this, in addition to the less healthy diet, explains the higher mortality of the elderly with a bad smell: the risk of dying within ten years is 46% higher for those who are not over 70 years old.

According to the criteria of The Trust Project

Know more

• Covid 19

• Coronavirus

• Science and Health

• HBPR

COVID-19 Epidemiologists Warn: "We hope the rebound does not cause another wave"

Coronavirus Why we can never live with Covid as with the flu

Covid-19 90% of the vaccinated population is still far away: "Some Autonomous Communities are going to arrive, it is difficult for all of them to do so"

See links of interest

• The Palm

• Last News

• What

• Holidays 2021

• 2022 business calendar

• Christmas Lottery 2021

• Loteria del Niño 2022