RALEIGH, N.C. — Last February, Ruth Sheehan recovered from a COVID-19 infection that took away her sense of smell.
Nearly two years later, her olfactory world is still dark. The smells of perfume, the Thanksgiving turkey, subtle food seasoning and coffee are similarly lost on her nostrils.
Sheehan said she is grateful she mostly came away from the infection unscathed but added: “I definitely miss smelling things. I figured eventually it would come back but it just hasn’t.”
Most people who lose their sense of smell from a COVID infection recover within a few weeks. But an unlucky minority of the population — about 5% according to one study — experience smell and taste loss months or years after their initial infection.
Duke researchers may have finally figured out what is happening 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 the condition, which so far lacks an effective treatment, said Dr. Bradley Goldstein, a Duke neuroscientist who led the research.
Ivy Ceballo, Tampa Bay Times
Wine rep Tara Simmons poses for a portrait on Feb. 12, 2021, at Cru Cellars in Tampa, Fa. Simmons knew she contracted COVID-19 when she couldn't smell the food she poured for her dogs a few days after the New Year's. "It is the weirdest symptom of any illness I've ever experienced to be able to breathe out of your nose, but not smell," Simmons said.
The researchers gathered 24 nose-tissue samples: nine from people with long-term smell loss from COVID, two from patients who recovered from COVID without smell loss, and 13 from people who never had COVID at all.
“The findings appeared pretty striking to us — there really are some very obvious differences,” Goldstein said.
Under the microscope, his research team found that people with long-term smell loss had obvious inflammation in a part of the nose dedicated to smell.
“I’m not talking about sort of this rip-roaring, severe nasal inflammation where you’re super congested, blowing your nose and feeling like you’re sick,” he said. “It’s more at a local microscopic level.”
That inflammation could explain why the samples from the smell-loss group had substantially fewer olfactory nerve cells, the “key cells” for smelling, Goldstein said.
Furthermore, they found that the inflammation was likely hindering the body’s ability to regenerate the depleted nerve cells.
Now that scientists have identified the types of immune cells likely responsible for smell loss, Goldstein said he hopes doctors will look into whether drugs that target those inflammatory signals can be repurposed.
The findings in Wednesday’s paper could also have implications for the treatment of long COVID more broadly, Goldstein said.
“Long COVID can affect lots of different organs in our body,” he said. “It’s possible that a very similar process is happening in those other places.”
Many mysteries about COVID related to smell loss still exist.
The most outstanding remaining question is why some people, like Sheehan, experience persistent smell loss while others recover. Goldstein hypothesized that it could have to do with which viruses people were previously exposed to .
Goldstein said a loss of smell can have a significant impact on quality of life. Some studies show an association between smell loss and heightened anxiety and depression.
“It’s one of those things that’s sometimes a bit underappreciated until it’s damaged or not working,” he said. “Then people realize how important it is.”
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Zigres // Shutterstock
Most people who get infected with the coronavirus recover within a few weeks. However, some continue to experience symptoms weeks or even months after they are infected. They have what are known as long-haul symptoms of COVID-19. As such, they are sometimes called COVID-19 long-haulers. Sometimes, even patients who had a mild or asymptomatic coronavirus infection can become long-haulers.
Scientists want to learn more about who becomes a long-hauler and why. This knowledge can help shape public policy, and determine the best standards of care and precautions to prevent viral transmission of the disease.
An advocacy group called Patient-Led Research for COVID-19 released its first report in May 2020, to provide an in-depth look at the experiences of more than 600 COVID-19 long-haulers. Susannah Fox, who studies online communities of patients with chronic conditions, told MIT Technology Review in August 2020 that such patient groups will be more important to health professionals, particularly during crises such as the coronavirus, that cause health professionals to be overwhelmed.
“The future of health care and technology is being built on such communities,” Fox said. She added that some of the earliest users of online bulletin boards and other online communities were patients with chronic diseases.
Cognitive FX compiled a list of long-term COVID-19 symptoms based on research and data from experts at institutions across the world, including the Centers for Disease Control and Prevention, Mayo Clinic, Northwestern University, and New York-Presbyterian/Columbia University.
Zigres // Shutterstock
Most people who get infected with the coronavirus recover within a few weeks. However, some continue to experience symptoms weeks or even months after they are infected. They have what are known as long-haul symptoms of COVID-19. As such, they are sometimes called COVID-19 long-haulers. Sometimes, even patients who had a mild or asymptomatic coronavirus infection can become long-haulers.
Scientists want to learn more about who becomes a long-hauler and why. This knowledge can help shape public policy, and determine the best standards of care and precautions to prevent viral transmission of the disease.
An advocacy group called Patient-Led Research for COVID-19 released its first report in May 2020, to provide an in-depth look at the experiences of more than 600 COVID-19 long-haulers. Susannah Fox, who studies online communities of patients with chronic conditions, told MIT Technology Review in August 2020 that such patient groups will be more important to health professionals, particularly during crises such as the coronavirus, that cause health professionals to be overwhelmed.
“The future of health care and technology is being built on such communities,” Fox said. She added that some of the earliest users of online bulletin boards and other online communities were patients with chronic diseases.
Cognitive FX compiled a list of long-term COVID-19 symptoms based on research and data from experts at institutions across the world, including the Centers for Disease Control and Prevention, Mayo Clinic, Northwestern University, and New York-Presbyterian/Columbia University.
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Monkey Business Images // Shutterstock
Among 100 people who presented to Northwestern Memorial Hospital’s Neuro-COVID-19 clinic in Chicago, with symptoms compatible with the Infectious Diseases Society of America COVID-19 guidelines, 59% reported dysgeusia, or an impaired sense of taste, and 55% reported anosmia, or an altered sense of smell. The patients were seen at the hospital, which operates in a partnership with Northwestern University’s Feinberg School of Medicine, an average of five to six months after the onset of COVID-19 symptoms. Dysgeusia and anosmia may be the result of viral invasion of the olfactory cortex, the part of the brain associated with the sense of smell and taste.
Monkey Business Images // Shutterstock
Among 100 people who presented to Northwestern Memorial Hospital’s Neuro-COVID-19 clinic in Chicago, with symptoms compatible with the Infectious Diseases Society of America COVID-19 guidelines, 59% reported dysgeusia, or an impaired sense of taste, and 55% reported anosmia, or an altered sense of smell. The patients were seen at the hospital, which operates in a partnership with Northwestern University’s Feinberg School of Medicine, an average of five to six months after the onset of COVID-19 symptoms. Dysgeusia and anosmia may be the result of viral invasion of the olfactory cortex, the part of the brain associated with the sense of smell and taste.
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CGN089 // Shutterstock
Dyspnea, or difficulty breathing, is the most common long-haul symptom of COVID-19. More than 40% to almost 70% of patients with COVID-19 report having trouble breathing 60 to 100 days after diagnosis or hospitalization. Dyspnea has been linked to viral damage of the alveolar and epithelial cells in the lungs, and inflammatory damage to vascular cells. Researchers have found corticosteroids may help some long-haul COVID-19 patients with residual lung inflammation or persistent inflammatory interstitial lung disease.
CGN089 // Shutterstock
Dyspnea, or difficulty breathing, is the most common long-haul symptom of COVID-19. More than 40% to almost 70% of patients with COVID-19 report having trouble breathing 60 to 100 days after diagnosis or hospitalization. Dyspnea has been linked to viral damage of the alveolar and epithelial cells in the lungs, and inflammatory damage to vascular cells. Researchers have found corticosteroids may help some long-haul COVID-19 patients with residual lung inflammation or persistent inflammatory interstitial lung disease.
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fizkes // Shutterstock
Cognitive impairment after COVID-19 recovery can present as trouble with concentration, memory, understanding words and language, and/or executive function. These cognitive difficulties may be the result of damage to the hippocampus, the part of the brain that plays an important role in learning and memory. Damage to the hippocampus may put people with COVID-19 long-haul symptoms at risk for the hippocampal-related degeneration characteristic of Alzheimer’s disease.
fizkes // Shutterstock
Cognitive impairment after COVID-19 recovery can present as trouble with concentration, memory, understanding words and language, and/or executive function. These cognitive difficulties may be the result of damage to the hippocampus, the part of the brain that plays an important role in learning and memory. Damage to the hippocampus may put people with COVID-19 long-haul symptoms at risk for the hippocampal-related degeneration characteristic of Alzheimer’s disease.
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Doro Guzenda // Shutterstock
The coronavirus that causes COVID-19 can make blood cells more likely to coagulate, or clump and form clots. Specifically, heart damage caused by COVID-19 is likely the result of clots in the small vessels, or capillaries, in the heart. The risk of blood clots in those with long-haul COVID-19 may be associated with damage from severe inflammation, although scientists don’t know how long the inflammation can persist. Doctors might want to treat blood clots in those with long-haul COVID-19 with low-molecular weight heparin and direct oral anticoagulants versus vitamin K antagonists, because patients taking vitamin K antagonists need frequent blood tests to monitor medication levels.
Doro Guzenda // Shutterstock
The coronavirus that causes COVID-19 can make blood cells more likely to coagulate, or clump and form clots. Specifically, heart damage caused by COVID-19 is likely the result of clots in the small vessels, or capillaries, in the heart. The risk of blood clots in those with long-haul COVID-19 may be associated with damage from severe inflammation, although scientists don’t know how long the inflammation can persist. Doctors might want to treat blood clots in those with long-haul COVID-19 with low-molecular weight heparin and direct oral anticoagulants versus vitamin K antagonists, because patients taking vitamin K antagonists need frequent blood tests to monitor medication levels.
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Photographee.eu // Shutterstock
Patients with long-haul COVID-19 may develop or will continue to experience neuropsychiatric symptoms, including insomnia, or sleeplessness, for months after they are initially infected. These symptoms may be the result of nerve cell damage due to inflammation. Levels of immune system activation are directly associated with cognitive and behavioral changes. Although little compelling evidence exists that the coronavirus that causes COVID-19 infects neurons, autopsies have found evidence that the virus causes changes in the brain that promote inflammation in nerve cells and blood vessels in the brain. Inflammaging, the chronic low-level brain inflammation that develops with age, may also play a role in the persistent psychiatric effects of COVID-19.
Photographee.eu // Shutterstock
Patients with long-haul COVID-19 may develop or will continue to experience neuropsychiatric symptoms, including insomnia, or sleeplessness, for months after they are initially infected. These symptoms may be the result of nerve cell damage due to inflammation. Levels of immune system activation are directly associated with cognitive and behavioral changes. Although little compelling evidence exists that the coronavirus that causes COVID-19 infects neurons, autopsies have found evidence that the virus causes changes in the brain that promote inflammation in nerve cells and blood vessels in the brain. Inflammaging, the chronic low-level brain inflammation that develops with age, may also play a role in the persistent psychiatric effects of COVID-19.
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Canva
Dizziness, sometimes called vertigo, has long been associated with viral infections. So researchers are not really surprised that studies from around the world have found vertigo is one of the most common symptoms of COVID-19. Scientists in Pakistan believe that the coronavirus enters the nervous system via the circulatory system, and binds to the angiotensin-converting enzyme 2 receptors in the lining of the capillaries in the brain. Hypoxia, or insufficient oxygen delivery, and damage caused by blood clots and inflammation are other possible ways nervous system damage can cause vertigo in those with long-haul COVID-19.
Canva
Dizziness, sometimes called vertigo, has long been associated with viral infections. So researchers are not really surprised that studies from around the world have found vertigo is one of the most common symptoms of COVID-19. Scientists in Pakistan believe that the coronavirus enters the nervous system via the circulatory system, and binds to the angiotensin-converting enzyme 2 receptors in the lining of the capillaries in the brain. Hypoxia, or insufficient oxygen delivery, and damage caused by blood clots and inflammation are other possible ways nervous system damage can cause vertigo in those with long-haul COVID-19.
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fizkes // Shutterstock
Scientists do not know much about what causes post-COVID-19 fatigue, also called post-exertional malaise or chronic fatigue/myalgic encephalopathy, following viral infection. One possible explanation is that while the body fights off the coronavirus, the immune system releases proteins that promote inflammation and can stimulate the immune response. These proteins are called cytokines, and they are also responsible for the symptoms of post-COVID-19 fatigue. However, cytokine levels sometimes do not return to normal and cause ongoing symptoms.
fizkes // Shutterstock
Scientists do not know much about what causes post-COVID-19 fatigue, also called post-exertional malaise or chronic fatigue/myalgic encephalopathy, following viral infection. One possible explanation is that while the body fights off the coronavirus, the immune system releases proteins that promote inflammation and can stimulate the immune response. These proteins are called cytokines, and they are also responsible for the symptoms of post-COVID-19 fatigue. However, cytokine levels sometimes do not return to normal and cause ongoing symptoms.
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Africa Studio // Shutterstock
Viral infection, inflammation and the immune response, and a decrease in the number of, or downregulation of, angiotensin-converting enzyme 2 receptors may be the root cause of chest pain and heart palpitations in those with long-haul COVID-19. Infection, inflammation, and the downregulation of ACE2 receptors damage the heart muscle; the pericardium, or the sac around the heart; and the conduction system that controls the heartbeat by conducting electrical impulses through the heart. Scarring of the heart muscle can lead to palpitations, or arrhythmias, as can cytokines, which are proteins that stimulate the immune response and promote inflammation.
This story originally appeared on Cognitive FX and was produced and distributed in partnership with Stacker Studio.
Africa Studio // Shutterstock
Viral infection, inflammation and the immune response, and a decrease in the number of, or downregulation of, angiotensin-converting enzyme 2 receptors may be the root cause of chest pain and heart palpitations in those with long-haul COVID-19. Infection, inflammation, and the downregulation of ACE2 receptors damage the heart muscle; the pericardium, or the sac around the heart; and the conduction system that controls the heartbeat by conducting electrical impulses through the heart. Scarring of the heart muscle can lead to palpitations, or arrhythmias, as can cytokines, which are proteins that stimulate the immune response and promote inflammation.
This story originally appeared on Cognitive FX and was produced and distributed in partnership with Stacker Studio.
