Posted by Anosmia and COVID-19
With the Thanksgiving and Christmas holidays just around the corner, the local grocery stores are starting to pack holiday favorites: cranberries, green beans, pumpkin pies, turkeys, and ham. The special smell of holiday dinners is associated with family time and enjoyment. Smell is such an important sense, especially when it comes to enjoying food. Since the tongue can only taste five tastes, two of which are sour and bitter, our enjoyment of food is thanks to odor molecules that move up the pharynx into the posterior nasal cavity. Our sense of smell is what makes delicious food so enjoyable. Anosmia is the loss of the sense of smell. It often happens when the olfactory nerve gets severed due to blunt force trauma to the head. The sensory neurons of the olfactory epithelium function for one to four months, while new sensory neurons are made on a regular basis. The replacement of olfactory neurons declines with age, so elderly individuals often report their food tasting bland (Betts et al., 2022, # 527). Anosmia has become synonymous with COVID-19. In fact, olfactory dysfunction was the most specific syndrome of COVID-19. More than 600 million people have been infected with COVID-19, and losing their smell was often when people knew without a doubt that they had COVID-19 (Faulet et al., 2023, #1). They could not smell and a result, taste their food. Even though, most people regained their sense of smell once they were done with the acute stage of the disease; some still reported symptoms six months later. A specific assessment conducted among healthcare workers discovered that a staggering 61% still had olfactory dysfunction two years after they had COVID-19 (Frasnelli et al., 2024, #2).
There were two pioneer studies that also reported an association between olfactory deficits and mental disorders (Faulet et al., 2023, #1). The same studies reported that there were more females affected by the loss of smell than males. Compared to patients without anosmia during acute COVID-19 infection, individuals with anosmia had significantly more symptoms of depression, anxiety, post-traumatic stress, and insomnia, as well as more anxiety disorders 4 months after hospitalization (Faulet et al., 2023, #3). This particular study showed the connection between acute anosmia and inflammation in the limbic system in COVID-19 sufferers. The study also brought to light that sensitivity to olfaction could be a sign of potential psychiatric outcomes (Faulet et al., 2023, #3).
Healthcare professionals were among the population groups most affected by long-term COVID-19 consequences (Frasnelli et al., 2024, #2). So how does COVID-19 cause anosmia? Even though this phenomenon is still being researched, the leading explanation is that the virus infects supporting cells known as sustentacular cells, whose job is to nourish the olfactory mucosa. This results in cell death of olfactory receptor neurons and, consequently, olfactory dysfunction (Frasnelli et al., 2024, #8). Usually, the olfactory has an excellent ability to fully regenerate. Scientists are not quite sure why some individuals do not completely regain their olfactory abilities (Frasnelli et al., 2024, #8).
References:
Betts, J. G., Desaix, P., Johnson, E., Johnson, J. E., Korol, O., Kruse, D., Poe, B., Wise, J. A., Womble, M. D., & Young, K. A. (2022). Anatomy and Physiology 2e. OpenStax.
Faulet, T., Gasnier, M., & Lecoq, A.-L. (2023, September–October). Anosmia during acute COVID-19 and psychiatric outcomes 4 months later: Results from the prospective COMEBAC cohort. General Hospital Psychiatry, 84, 260-261. Retrieved November 6, 2024, from https://www.sciencedirect.com/science/article/pii/S0163834323001007?via%3Dihub
Frasnelli, J., Tognetti, A., Winter, A. L., & Thunnel, E. (2024, July 1). High prevalence of long-term olfactory disorders in healthcare workers after COVID-19: A case-control study. PLoS ONE. PsycInfo.
My project in progress
This is my finished collage demonstrating the concept of COVID-19 causing anosmia which influences the process of food enjoyment.