Many patients with COVID-19 are experiencing loss of smell and taste, which can last for months after recovery, and in some cases the senses may not return. A study published in the European Archives of Oto-Rhino-Laryngology looked at 417 patients with mild to moderate COVID-19 in Europe and found 88% and 86% reported taste and smell dysfunctions, respectively.
At least a quarter of patients regained the ability to taste and smell within 2 weeks of other symptoms ceasing, but more data is needed to understand how long sensory dysfunction lasts for the remaining patients who have not seen an improvement.
The breakdown of smell receptors caused by the coronavirus seemingly occurs without nasal congestion, which is typically how these senses become disrupted. According to Danielle Reed, MD, associate director of the Monell Chemical Senses Center in Philadelphia, one theory is that the olfactory receptors that go to the brain are self-destructing as a means of protection from carrying the virus to the brain.
“It could be a healthy reaction to the virus. If that doesn’t work, maybe people do get sicker,” said Dr. Reed. “It might be a positive takeaway from what is obviously a devastating loss to people.”
Taste and smell disorders can occur for a variety of reasons, such as age or health conditions. Influenza can temporarily numb these senses, while other acute respiratory illnesses might cause permanent sensory damage.
The loss of these senses can also affect patients’ mental wellness. In a British study of taste and smell disorders, patients reported emotions such as anxiety, depression, isolation, and low self-esteem. Pamela Dalton, PhD, a chemosensory scientist also from the Monell Center, asserts that sensory loss can trigger negative emotions. Losing the ability to enjoy one’s favorite foods or smell a loved one, according to Dr. Dalton, can lead to less serotonin flowing to the brain.
Sources: The Wall Street Journal, June 1, 2020; Lechien JR, Chiesa-Estomba CM, De Siati DR, et al. Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study. Eur Arch Otorhinolaryngol. 2020 Apr 6 : 1–11. [Epub ahead of print]