One of the characteristic symptoms of COVID 19 is loss of smell. As a rule, the ability to smell smells returns several weeks after the onset of the symptom, or even after a few days. However, in some patients, the sense of smell does not return at all.
But this does not mean that in this case you will have to forget about smells and taste forever. In such cases, doctors use a special therapy to train the brain to smell, which was developed 20 years ago. In the past decade, it has been used to help restore the sense of smell lost due to other viral infections such as the common cold or the flu, or as a result of traumatic brain injury. Next, let’s look at what this therapy is, how it works, and how effective it is in general.
Restoration of smell after coronavirus
About two decades ago, scientists began to document olfactory disorders in large populations. As it turned out, temporary or permanent occurs much more often than previously thought. However, there was no way to solve this problem.
Lack of smell is not such a terrible symptom as a change in a person’s personality , nevertheless, it significantly affects the quality of life, and even sometimes leads to depression.
Thomas Hummel, an expert in this field at the Clinic for Smell and Taste at the Dresden Medical School in Germany, knew that the olfactory system has a unique ability to continuously regenerate itself throughout a person’s life.
Moreover, as experiments have shown, people who are not able to smell certain smells can learn to perceive them after repeated exposure to the smell. To test this hypothesis, the scientist and his colleagues conducted an experiment in which 40 patients took part.
The researchers asked them to inhale four scents of essential oils – rose, lemon, eucalyptus and clove. Volunteers sniffed the oils for 10 seconds twice a day. The experiment lasted 12 weeks.
To evaluate the effectiveness of the therapy, the research team asked participants in the experiment to identify some odors before and after the therapy. As a result, the authors found that about 30% of participants actually improved their sense of smell.
Since then, numerous studies have been carried out by other scientists. As a rule, improvements were noted, but they were not great – in some cases, the sense of smell was restored by 25%, in others – by 70%. As Thomas Hummel himself says, effectiveness may depend on age, as well as how serious the problems were and how long the ability to smell was absent.
How exercise helps restore your sense of smell
Until the end, the mechanism that leads to improvements in the sense of smell as a result of therapy is not clear to scientists. However, there are some hypotheses in this regard. For example, Thomas Hummel believes that exposing people with a smell deficiency to odors can speed up the regeneration of odor-determining cells.
Other scientists suggest that such learning to smell may improve the survival and function of new odor-detecting cells. The therapy stimulates them, which gives them the opportunity to connect with the brain and eventually restore their loss of smell.
Smell Therapy for COVID-19
Unlike some other viruses that infect the cells responsible for detecting odors, SARS-CoV-2 spares them. Instead, the coronavirus infects surrounding “support” cells that have the ACE2 receptor. The latter is known to be required by SARS-CoV-2 to infect the cell.
To protect the body from the virus, immune cells rush to the site of infection and generate antiviral proteins, which, according to one study, can reduce the activity of genes responsible for odor receptors.
However, approximately 80% of COVID-19 patients who lost their sense of smell regained it without any treatment. Within six months, the sense of smell returns to 95% of patients. Smell training may be beneficial for COVID-19 survivors who have lost their sense of smell for more than six weeks, experts say.
According to patients, they begin to notice an improvement in the sixth week of therapy. Therefore, at present, learning to smell, despite the lack of guarantees, is considered the most effective, affordable, inexpensive and generally safe way to solve the problem.
Finally, we recall that scientists associate the loss of smell with COVID-19 is associated not only with gene suppression, but also with brain damage. Moreover, not only the ability to distinguish smells suffers from this, but also mental abilities.