COVID-19 drives new research into smell loss

COVID-19 has left thousands with a distorted or lost sense of smell, but some of those who have been affected are helping researchers get a better handle on the phenomenon. This understanding and growing awareness of olfactory disorders could help people facing smell loss from COVID-19 or other causes, according to a cover story in Chemical & Engineering News, an independent news outlet of the American Chemical Society.

In the nose, neurons that detect odor molecules are surrounded by support cells, which hold the neurons in place, writes Senior Editor Laura Howes. SARS-CoV-2 attacks these support cells, which can release inflammatory factors that affect DNA organization in the neurons, messing up protein production and interfering with the process of smelling. While most people regain their sense of smell and taste within a couple of weeks of being infected with the virus, about 5% of people experience persistent changes. Gene scrambling might also be responsible for the disordered sense of smell — a phenomenon known as parosmia — that some experience, causing certain scents, such as meat and coffee, to seem disgusting.

Understanding the mechanisms of olfaction and the reasons that smell loss occurs will help drug discovery efforts. Some potential treatments are already in clinical trials, including injections of platelet-rich plasma and topical vitamin A. Researchers are also looking at transplanting tissues and building olfactory implants as possible solutions. One approach, smell training, involves sniffing a sequence of four essential oils and can help people with parosmia recover more quickly. Researchers are continuing to find ways to improve a damaged sense of smell, which could greatly improve the quality of life for those who are affected.