Can ‘sniff training’ restore the smell of COVID survivors?

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Cat Berner slipped a chicken into the oven in November and turned to cutting vegetables. It didn’t take long for her roommate to rush into the kitchen of their San Francisco apartment shouting, “What’s on fire?

Berner turned around. “What are you talking about?”

Berner, 31, an executive assistant for a venture capital firm, remembers the day as a turning point in her ongoing efforts to find the smell stolen by the coronavirus. It came days after she and her friends, who had vowed to only socialize with each other, threw a Halloween party and gave each other COVID-19.

“It was a big wake-up call for me,” Berner said of the day she charred the chicken and couldn’t smell it scorching. “Losing your sense of smell seems like it could be taken lightly, but in some situations it is very serious. “

Now, with a lingering symptom that puts her in the company of long-haul CO VIDs, Berner is following the only known strategy doctors recommend to try and fix the problem: “sniff training.”

Anosmia – a lost sense of smell – is one of the most common side effects of COVID, affecting about 60% of people with it. In the United States alone, that’s about 20 million people.

The good news is that the ability to recognize odors returns for about 95% of them within six months, said Dr Patricia Loftus, an otolaryngologist at UCSF who treats patients with loss of heart. post-COVID odor.

But that leaves around 1 million people in the United States alone with persistent disability – and little data to show what happens after that. A very small study of 51 COVID survivors published in June in the medical journal JAMA found that 4% of participants – two people – had not regained their sense of smell eight months to one year after infection.

These are people with persistent anosmia, like Berner, who still can’t smell if the chicken is burning – or if the gas is on, or if the milk is bad – long after recovering from COVID.

Video: Chronicle of San Francisco

For some, including Berner, anosmia is just one of the persistent olfactory dysfunctions induced by COVID. There is also a parosmia, in which a whiff of perfume can instead smell like the interior of a kennel – strongly distorted. And hyposmia, where odors are perceived only weakly. And the ghost, the ghost smells, like smelling burnt chicken when it’s just a salad for dinner.

At first, researchers wondered if the coronavirus was infecting nerves in the olfactory epithelium, a piece of tissue at the top of the nose near the base of the brain that helps people smell.

But that’s not quite what is happening.

“What we and others have found is that the viral effects are more mediated by the impact on the supporting cells of the nerves,” said Dr. Jonathan Overdevest, rhinology expert at Columbia University Irving Medical Center. At New York.

In other words, the nerves that perceive smells are like cell phone towers with antennas, he said. And the support cells are like scaffolding around the towers.

The coronavirus appears to be disrupting scaffolding and antennas, not cell phone towers themselves.

“The loss of this scaffolding can make the towers more vulnerable,” Overdevest said. “The towers still exist, but the antennas are getting lost,” reducing the ability to perceive smells. It can also change the smell of things.

Overdevest and a colleague, Stavros Lomvardas, got a grant from the National Institutes of Health to learn more about how the process works and what to do next.

It’s still unclear why most people who lose their scent from COVID recover and why others don’t, Overdevest said.

The clues to the mystery lie at the molecular level, beyond the reach of x-rays and MRIs. So the more researchers can understand what’s going on at that level, the more likely they’ll be to learn how to fix it, Overdevest said.

For now, sniffing training is how people with long-term smell problems most often try to reinforce the scaffolding around the cell phone towers of their nose, and perhaps restore the antennae.

“We like to say that sniffing training is physical therapy for your scent,” said Loftus, of UCSF.

One of his patients, Berner, got ready for his nasal workout the other day in his sunny San Francisco apartment, displaying four small bottles of concentrated plant liquids called essential oils.

Any strong scent will do, you think, from cologne to kitchen spices. But the prescription is usually the same: sniff each one for 15 seconds, twice a day. Avoid taking a deep breath. Instead, little “rabbit sniffs” will direct the aromas to the correct nasal receptors.

Berner unscrewed the first bottle and the rabbit sniffed for 15 seconds, taking about 20 small inhalations. Putting this bottle down, she opened the second and repeated the process, then did the same with the third and fourth.

The scents Berner chose were lemongrass, peppermint, lavender and tea tree. What she smelled was wet dog, smoke, rotten candy, and candy.

“It’s pretty disheartening not to have huge improvements,” said Berner, acknowledging that after so many months she can only bring herself to train once a day.

It is not known if sniffing training helps. Conclusive data is lacking, although people lost their sense of smell to other viruses and head trauma long before COVID-19 appeared.

Several research projects are however underway, including a clinical trial with 240 participants with COVID-induced olfactory dysfunction. Researchers at the Washington University School of Medicine in Missouri are hoping to find out whether sniffing training might work better if people simultaneously look at a photo of the aromatic object – a rose or lemon, for example. They also want to test if the results improve if the sniffers smell something they particularly enjoy, like coffee, instead of a scent they don’t like or have no connection with.

Some experts are also investigating whether steroids given to specific areas of the nose can improve symptoms.

“There are anecdotal reports that steroids help, but there are a few well-done studies that haven’t seen any benefit,” said Nancy Rawson, cell biologist and vice president of the Monell Chemical Senses Center in Philadelphia, an organization nonprofit scientist. Research Institute. “The balance right now is against him.”

Steroids are powerful anti-inflammatory drugs. But if the inflammation doesn’t cause the loss of smell – if it’s caused by the loss of supporting cells, for example, that scaffolding for nose cell towers – “one steroid may not be the right one. thing, ”Rawson said.

In fact, it can be a bad thing if the tissue is trying to regenerate, she said.

While too much inflammation can harm the body, “a little inflammation actually helps promote regeneration,” Rawson said, as it signals the tissues to start healing.

The general lack of certainty and solutions is frustrating, not only for people like Berner who have impaired sense of smell, but for those whose job it is to help them.

Doctors can provide glasses for the visually impaired and hearing aids or cochlear implants for the hard of hearing.

“But I don’t know anyone who works on an olfactory simulator,” said Loftus of UCSF. “We are far from that.

“But I’m hopeful because COVID started the conversation on this. “

Nanette Asimov is a writer for the San Francisco Chronicle. Email: [email protected] Twitter: @NanetteAsimov



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