[박문일의 생명여행](36) Olfactory research sparked by Long Covid
The global corona pandemic seems to be coming to an end. We are entering the so-called Post-Corona era. So far, more than 600 million people have been infected worldwide and the death toll has passed 6 million.
Those who survive should worry about the aftereffects of the corona infection. That’s because one-third of people who are experiencing the so-called Long COVID symptoms are three months after infection. Long covid refers to the aftereffects of COVID-19, which means that various symptoms of unknown cause continue for a while after suffering from COVID-19. The World Health Organization (WHO) defines long-covid-19 as “a person who has or may have been confirmed with COVID-19 experiences symptoms that cannot be explained by other diagnoses for at least two months, usually three months.”
The duration of long covid symptoms varies by research institute, but it is known to be as short as 4 weeks or more after infection and as long as 12 weeks or more. However, loss of sense of smell, one of the symptoms of Long Covid, is of particular interest to scientists. For millions of people, one of the hallmark symptoms of COVID-19 is loss of smell. Even after the coronavirus has healed, many people are experiencing a world that has changed or has lost their ability to smell than before. It means that the ability to enjoy food or the fragrance of nature is weakened.
As the number of people complaining of loss of smell, one of the symptoms of Long Covid, increases, scientists are naturally more interested in the sense of smell, which has been overlooked in our sense organs for a long time. In fact, although the sense of smell is one of the five human senses and is very important to life, the symptoms of COVID-19 have been somewhat underestimated compared to other symptoms. In fact, doctors haven’t used the sense of smell much in the diagnosis of various diseases. The ancient Greeks gave many examples of using the sense of smell to make a diagnosis, but the idea was largely overlooked by modern doctors.
There are various odor-sensing neurons in the epithelium inside the human nose, and when the Corona 19 virus invades these neurons, it can cause not only loss of smell but also neurological complications. The olfactory neurons, in particular, are connected via nerve fibers to the brain’s olfactory processing centers, where the virus spreads faster and the neurons begin to destroy, alerting the immune system. As the inflammation worsens, the immune signaling system collapses, ultimately destroying the ability of the olfactory neurons inside the nose to transmit odor information to the brain.
Most of the newly discovered scientific interest is, of course, medically studied. Researchers focused on research into how the COVID-19 virus causes loss of smell in humans, and why its effects differ between individuals and different strains of the COVID-19 virus. This has sparked renewed interest in the treatment of olfactory disorders, which we believe will aid in the treatment of people suffering from this condition as a result of COVID-19. Of course, this study could also benefit 10% of the general population who already have olfactory disease.
As part of these efforts, efforts to improve the ‘olfactory training technique’, one of the existing methods for recovering the sense of smell, are progressing rapidly. In addition, attempts are being made to develop an electronic implant that restores the human sense of smell.
Humans have long used dogs’ superior sense of smell, and the 300 million olfactory receptors in their noses have been routinely used to detect bombs, drugs, firearms and people. Dogs are now being used in the experimental realm of smelling human diseases such as diabetes and cancer.
In fact, American veterinarian Cynthia Otto is studying how to harness the animal’s ability to smell human diseases, including COVID-19, a portable electronic device that, like dogs, accurately and reliably recognizes the smell of various diseases. Efforts are underway to develop the device.
Researchers are also focusing their research efforts on the special inner workings of the human sense of smell. It started from the fact that smell is closely related to human memory. Scientists argue that the ability to smell is important for people to recall very specific memories, and it can also be used to strengthen and heal our brains.
In fact, smell is deeply ingrained in our emotional memory. The experience of smells that evoke vivid memories will be familiar to many. <잃어버린 시간을 찾아서>As author Marcel Proust said, “The smell and taste of things are ready to remind us for as long as the soul.” So, smells can allow us to time travel in our minds and evoke various emotions we have experienced in the past. For example, a bite of a madeleine cake and a sip of fragrant tea brings you back to the happy childhood memories of Sunday mornings with your loved ones.
Therefore, the neurobiology that underpins the close link between smell and memory has also received considerable attention in recent years. Secrets are being revealed in which certain smells instantly remind you of other places and times. The scientific background of how smell affects human behavior, our emotional state, and our partner choice is increasingly being explored. And the various abilities of olfactory receptors in tissues and organs around the human body are beginning to be scientifically explained. Putting all these changes together, it seems that the world has now realized the special importance of smell. Even though it is a trace left by Long Covid.
Now that the corona pandemic is ending around the world, I think that it would be good for mankind, who are suffering from the symptoms of long covid, to recover properly even if they have the ability to smell. The ability to avoid bad odors is good, but more importantly, isn’t the ability to sense scents lost? Our beautiful old memories will disappear in vain… .
