Raleigh, North Carolina — Last February, Ruth Sheehan lost her sense of smell after recovering from a COVID-19 infection.
Nearly two years later, her olfactory world remains dark. Perfume, Thanksgiving turkey, subtle seasonings, and coffee smells are likewise lost through her nostrils.
Sheehan is grateful to have survived the infection mostly unscathed, but added: I thought it would come back eventually, but it didn’t. ”
Most people who lose their sense of smell due to COVID-19 recover within a few weeks. Unfortunately, however, a minority of the population — about 5%, according to one study — experience loss of smell and taste months or years after initial infection.
Duke’s researchers may have finally figured out what’s going on in the noses of people like Sheehan who never fully recover. The process is described in a paper published Wednesday in the journal Science Translational Medicine.
Understanding this mechanism could help doctors design treatments for conditions for which there are no effective treatments so far, said the Duke University neuroscientist who led the study. Bradley Goldstein, Ph.D.
Researchers collected 24 nasal tissue samples. Nine of them were from people with prolonged smell loss due to COVID, two were from people who had recovered from COVID but had no smell loss, and 13 were from people who had never experienced her COVID. rice field.
“The findings were very impressive to us. There are actually some very obvious differences,” says Goldstein.
Under the microscope, his team found that people with long-term loss of smell had obvious inflammation in the part of their nose that controls smell.
“I’m not talking about deafening, intense nasal inflammation that makes you very congested, blows your nose, makes you sick,” he said. rice field. “It’s at the local, microscopic level.”
According to Goldstein, this inflammation could explain why olfactory neurons, the “key cells” of smell, were so scarce in samples from the anosmia group.
Additionally, they found that inflammation likely interfered with the body’s ability to regenerate depleted nerve cells.
Now that scientists have identified the types of immune cells that may be responsible for the loss of smell, Goldstein hopes doctors will investigate whether drugs that target those inflammatory signals can be repurposed. There is
Goldstein said Wednesday’s paper’s findings could also have implications for broader treatments for COVID over the long term.
“The new coronavirus can affect different organs in our body,” he said. “It’s possible that a very similar process is happening elsewhere.”
There are still many mysteries about COVID related to smell loss.
The most important question that remains is why some people, like Sheehan, experience persistent odor loss while others recover. We hypothesized that it might be related to the virus we were exposed to.
Loss of the sense of smell can have a significant impact on quality of life, says Dr. Goldstein. Several studies have shown a link between loss of smell and increased anxiety and depression. .
“This is one of those things that can be a little underestimated until it’s damaged or doesn’t work,” he said. “Then people will understand how important it is.”