Until March, when everything started to taste like cardboard, Katherine Hansen had such a keen sense of smell that she could recreate almost any restaurant dish at home without the recipe, just remembering the smells and tastes.
Then came the coronavirus. One of Hansen’s first symptoms was loss of smell, and then taste. Hansen still can’t taste the food, and says he can’t even tolerate chewing it. He now lives mainly on soups and smoothies.
“I’m like someone who loses their sight as an adult,” said Hansen, a real estate agent who lives on the outskirts of Seattle. “They know how things should look. I know what I should know, but I can’t prove anything.”
Decreased sense of smell, called anosmia, has emerged as one of the telltale symptoms of COVID-19, the disease caused by coronavirus. It is the first symptom for some patients, and sometimes the only one. Often accompanied by an inability to taste, anosmia occurs abruptly and dramatically in these patients, almost as if a switch had been actuated.
Most regain their senses of smell and taste after recovering, usually within weeks. But in a minority of patients, like Hansen, the loss persists, and doctors do not know when they will regain those senses or whether they will.
Scientists know little about how the virus causes persistent anemia or how to cure it. However, cases are piling up as the coronavirus spreads around the world, and some experts fear the pandemic could leave a large number of people with a permanent loss of smell and taste. This possibility has sparked an urgent struggle among researchers to learn more about why patients are losing these essential senses and how to help them.
“Many people have been doing olfactory research for decades and have received little attention,” said Dolors Malaspina, a professor of psychiatry, neuroscience, genetics and genomics at Mount Sinai’s Icahn School of Medicine in New York City. “COVID is putting this field upside down.”
Smell is intimately linked to both taste and appetite, and anosmia often robs people of the pleasure of eating. But the sudden absence can also have a profound impact on mood and quality of life.
Studies have linked anosmia to social isolation and anhedonia, the inability to feel pleasure, as well as a strange feeling of disaffection and isolation. Memories and emotions are intrinsically linked to smell, and the olfactory system plays an important, though largely unrecognized, role in emotional well-being, said Sandeep Robert Datta, adjunct professor of neurobiology in the School of Medicine. of Harvard.
“Smell is not something we pay much attention to until it disappears,” said Pamela Dalton, who studies the link between smell and cognition and emotions at the Monell Center for Chemical Senses in Philadelphia. “Then people notice it, and it’s pretty distressing. Nothing is the same.”
British scientists studied the experiences of 9,000 COVID-19 patients who joined a Facebook support group set up by charity group AbScent between March 24 and September 30. Many members said they had not only lost the pleasure of eating, but also of socializing. The loss had weakened their ties with other people, by affecting intimate relationships and leaving them isolated, even separated from reality.
Loss of smell is a risk factor for anxiety and depression, so the implications of generalized anosmia are of deep concern to mental health experts. Malaspina and other researchers have found that olfactory dysfunction usually precedes social deficits in schizophrenia, and social isolation even in healthy people.
“From a public health perspective, that’s really important,” Datta said. “If the number of people with COVID is considered internationally, even if only ten percent have a longer-lasting odor loss, we’re possibly talking about millions of people.”
The most immediate effects can be nutritional. People with anosmia may continue to perceive the basic flavors: salty, sour, sweet, bitter, and umami. But the taste buds are relatively raw preceptors. Smell adds complexity to the perception of taste through hundreds of odor receptors that point to the brain.
Many people who cannot smell will lose their appetite, which puts them at risk for nutritional deficiencies and unwanted weight loss. Kara VanGuilder, who lives in Brookline, Massachusetts, said she had lost 9 pounds since March, when her sense of smell faded.
Smells also serve as a primitive alarm system that alerts humans to the dangers of our environment, such as fires or gas leaks. Decreased sense of smell in old age is one of the reasons why older people are more prone to accidents, such as fires caused by burning food on the stove.
Humans are constantly scouring their surroundings for odors that signal potential changes and damage, although the process is not always conscious, said Dalton of the Monell Center for Chemical Senses.
The smell alerts the worldly brain, like dirty clothes, and the risky one, like rotten food. Without this form of detection, “people get anxious about things,” Dalton commented.
What’s worse is that some COVID-19 survivors are plagued by phantom odors that are unpleasant and often harmful, such as the smell of burnt plastic, ammonia, or feces, a distortion called parosmia.
Eric Reynolds, a 51-year-old parole officer in Santa Maria, California, lost his sense of smell when he contracted COVID-19 in April. Now, he said, he often perceives unpleasant odors that he knows don’t exist. Diet drinks taste like dirt; soap and laundry detergent smell of stagnant water or ammonia.
“I can’t wash the dishes because it makes me nauseous,” Reynolds said. He’s also obsessed with the ghostly smells of fried corn and a smell that says “woman’s perfume smell”.
It’s not uncommon for patients like Reynolds to develop aversions to food related to their distorted perceptions, said Evan R. Reiter, medical director of the Center for Smell and Taste at the University of Virginia Commonwealth, which has been following recovery. of about 2,000 COVID-19 patients who lost their sense of smell.
One of his patients is recovering, but “now that he’s back, he says all or almost everything he eats will give him a taste or smell of gasoline,” Reiter said. Smell disorder can be part of the recovery process, as the receptors in the nose struggle to wake up again, sending signals to the brain that fail or are misread, he explained.
After loss of smell, “different populations or subtypes of receptors may be affected to varying degrees, so the signals the brain is used to receiving when eating a steak will be distorted and may trick the brain into thinking that dog poop or something that is not desirable is being eaten, ”Reiter concluded.