A new study reveals that COVID-19 can lead to long-lasting impairment of the sense of smell, even in those who don’t initially notice any changes. Led by the National Institutes of Health’s RECOVER initiative, the study highlights the need for routine post-COVID care to include olfactory testing.
A new study sheds light on the long-term impact of COVID-19 on the sense of smell, revealing that individuals who contracted the virus may suffer from lingering olfactory dysfunction for years, even if they have not noticed any issues.
Led by the National Institutes of Health’s RECOVER initiative and backed by the Clinical Science Core at NYU Langone Health, researchers from various institutions across the United States utilized an objective 40-odor test to explore the connection between COVID-19 and a reduced ability to smell, known as hyposmia.
The study found that 80% of participants who reported a change in their smelling ability after contracting COVID-19 scored poorly on a clinical scent-detection test conducted about two years later.
Of this subgroup, 23% were severely impaired or had completely lost their sense of smell.
Surprisingly, 66% of infected participants who did not notice any issues also scored abnormally low on the evaluation.
“Our findings confirm that those with a history of COVID-19 may be especially at risk for a weakened sense of smell, an issue that is already underrecognized among the general population,” co-lead author Leora Horwitz, a professor in the Departments of Population Health and Medicine at NYU Grossman School of Medicine, said in a news release.
Horwitz added that 60% of uninfected participants who did not report olfactory problems also performed poorly during the clinical evaluation.
Hyposmia has been linked to various health issues, including weight loss, reduced quality of life and depression. It can also impair a person’s ability to detect dangers such as spoiled food, gas leaks and smoke.
Furthermore, olfactory dysfunction has been flagged as an early sign of neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease.
While previous research has identified hyposmia as a symptom of COVID-19, most studies relied on self-reported data, which can be unreliable.
This new study, published today in JAMA Network Open, is the largest to date to examine loss of smell after COVID-19 using formal testing.
The research team assessed the olfactory function of 3,535 men and women using the University of Pennsylvania Smell Identification Test (UPSIT). This scratch-and-sniff evaluation is considered the gold standard for measuring olfactory function.
“These results suggest that health care providers should consider testing for loss of smell as a routine part of post-COVID care,” added Horwitz. “While patients may not notice right away, a dulled nose can have a profound impact on their mental and physical well-being.”
Efforts are underway to develop treatments to restore smelling ability in those affected by COVID-19, including vitamin A supplementation and olfactory training to rewire the brain’s response to odors. Horwitz noted that gaining a deeper understanding of how the coronavirus impacts the brain’s sensory and cognitive systems could help improve these therapies.
Horwitz pointed out that the study team did not directly evaluate loss of taste, which commonly occurs alongside smell issues. Furthermore, some participants who were uninfected may have been misclassified due to the absence of universal virus testing. This could account for the unexpectedly high rate of hyposmia found in individuals with no reported history of COVID-19, she explained.
Source: NYU Langone Health