Study: Those under 40 are more likely than older adults to recover COVID-related smell and taste loss
Sense of smell or taste returns within six months for 4 out of every 5 COVID-19 survivors who have lost these senses, and those under 40 are more likely to recover these senses than older adults, an ongoing Virginia Commonwealth University study found.
Among 798 respondents to the ongoing COVID-19 smell and taste loss survey who had tested positive for COVID-19 and reported a loss of smell or taste, participants who were younger than 40 recovered their sense of smell at a higher rate than those older than 40, according to study results published in the American Journal of Otolaryngology last month. The VCU study requires survey participants to be 18 years or older.
Evan Reiter, M.D., medical director of the Smell and Taste Disorders Center at VCU Health and a co-investigator on the study, said the latest data show 4 in 5 participants, regardless of age, regained their smell and taste within six months.
"With our cohort, we did see about an 80% recovery rate in a six-month period or longer," said Reiter, a professor and vice chair in the Department of Otolaryngology—Head and Neck Surgery at the VCU School of Medicine. "However, 20% is still a lot of people, given the millions that have been afflicted with COVID-19."
What symptoms COVID-19 survivors experienced and what pre-existing conditions they had also offered insights into their recovery. Those with a history of head injury were less likely to recover their sense of smell. Recovery was also less likely for those who had shortness of breath during COVID-19. However, those with nasal congestion had a higher likelihood of smell recovery.
"Increased likelihood of recovering smell in subjects with nasal congestion stands to reason simply because you can lose your sense of smell because you're badly congested and odors can't get into your nose," Reiter said. "Certainly a subset of those people who are congested might have just lost their sense of smell because they were badly congested, rather than because of nerve damage due to the virus, as in other cases."
There have been more than 230 million cases of COVID-19 worldwide, according to the World Health Organization. If estimates from the survey reflect populations worldwide, more than 20 million people could have lingering loss of smell or taste more than six months after their COVID-19 diagnosis.
Since April 2020 when news reports of smell and taste loss as a symptom of COVID-19 became widespread, researchers at VCU have been working to determine how long COVID-19-related smell or taste loss might last to help identify treatments or other considerations for the health of those who've lost these senses. To date, nearly 3,000 people across the U.S. have participated in the survey, which tracks symptoms over time.
Smell and Taste Disorders Center researchers for this ongoing study include Daniel Coelho, M.D., lead author and a professor in the Department of Otolaryngology—Head and Neck Surgery; Richard Costanzo, Ph.D., senior author, the center's research director and professor emeritus in the Department of Physiology and Biophysics; Zachary Kons, a medical student at VCU School of Medicine; and Reiter. Co-authors on the latest paper also include Yongyun Shin, Ph.D., an associate professor, and Serenity Budd, a Ph.D. student, both from the Department of Biostatistics at VCU School of Medicine.
Previous survey results published in April showed 43% of participants reported feeling depressed and 56% reported decreased enjoyment of life in general while experiencing loss of smell or taste. The most common quality-of-life concern was reduced enjoyment of food, with 87% of respondents indicating it was an issue. An inability to smell smoke was the most common safety risk, reported by 45% of those surveyed. Loss of appetite (55%) and unintentional weight loss (37%) continue to pose challenges for patients, Coelho says.
"The more we learn from those who've been affected, the better we can advise their health care providers and even individuals themselves on how to manage those symptoms," Coelho said. "Through this study, we continue to gain a clearer picture of the risks COVID-19 poses to quality of life, safety and long-term health and well-being while seeking answers on treatment."
For those looking for a reprieve from smell loss, smell training using essential oils may help.
"I continue to recommend that to my patients. It's low cost and low risk," Reiter said.
The Clinical Olfactory Working Group, an international group of physicians with a strong research interest in the sense of smell, recommended the method as an option early this year. The group found that smell (olfactory) training could help foster recovery of nerve damage.
"I'd also say potentially it may get people a little bit more tuned into whatever level of function they have left so it might make them more sensitive and better able to use the remaining sensors and neurons that are working," Reiter said.
And for those who might be concerned about the possibility of losing these senses, Reiter said a dose of prevention is what's needed.
"What the CDC and WHO have been saying—get vaccinated, wear a mask, hand hygiene—all of the seemingly simple things that are readily available at least here in the United States, fortunately, are important," Reiter said. "To prevent these long-term consequences, you really need to minimize your chances of getting the disease in the first place because, once it hits, we just right now don't really have a way to affect its course or affect its severity. Prevention is worth a thousand pounds of cure, in this case, because the cure isn't there."
Efforts toward a solution are in the works, though. Costanzo and Coelho's early-stage development of an implant device to restore sense of smell began years before the pandemic. The pair are optimistic that, when it's operational, it could be a source of hope for those with lasting smell loss.
"The international interest we've seen in finding solutions for smell loss, given its lasting impact on patients, has risen sharply during this pandemic," Costanzo said. "While we would hope the symptoms of these individuals improve—and most do—this device could make a difference for those whose sense of smell doesn't return."
The device would behave much like a cochlear implant, which restores hearing for those with hearing loss.
Teams across VCU School of Medicine have dedicated themselves to finding options for those with lingering symptoms of COVID-19, said Peter Buckley, M.D., dean of VCU School of Medicine. While providers at the Smell and Taste Disorders Center focus on smell and taste, others at VCU Health's Long COVID-19 Clinic focus on long-term symptoms of the heart, brain and lungs.
"Our faculty and health care providers have concentrated on problem-solving from the beginning of this pandemic to make the best possible care available to patients," Buckley said. "The studies conducted by the Smell and Taste Disorders Center have been a leading source of information on smell and taste loss and its impact on the mental and physical health of individuals experiencing those symptoms. I commend the researchers' efforts to gather and share that knowledge with providers nationwide for the well-being of all patients."
More information: Evan Reiter et al, Predictors of smell recovery in a nationwide prospective cohort of patients with COVID-19, American Journal of Otolaryngology (2021). DOI: 10.1016/j.amjoto.2021.103239