Early research suggests SARS-CoV-2 may enter the brain through the nose. It can infiltrate brain cells and create lasting neurological symptoms such as memory problems and trouble thinking .. Two new studies from the California National Primate Research Center in Toronto and the Rotman Research institute in Toronto suggest that the virus infects the brain directly. This could help explain why people may experience a variety of symptoms, even years after the initial Covid infection.
Neither of the studies, presented Wednesday during a meeting of the Society for Neuroscience, has been peer-reviewed, and neither is expected to answer all questions surrounding long Covid.
But they come as researchers worldwide are urgently trying to learn more about the mysterious and debilitating illness that is estimated to affect at least one-third of the more than 46 million people who have been infected in the U.S., as well as millions more globally.
Zeroing in on how the virus invades and affects the brain has the potential to defog the window into long Covid, an illness that doctors so far have been unable to appropriately define, diagnose or treat. We are still at the stage where it doesn’t even have a name. This is a problem,” Dr. Nir Silverstein, Director of the Center for Post Covid Care and Recovery at National Jewish Health Denver said. The new research was not conducted by Goldstein.
Invading the brain
The body’s natural blood-brain barrier usually does a good job at halting things like viruses before they can cross into the brain, though it is possible for viruses to sneak through. SARS-CoV-2, along with other viruses such as HIV, can also do this. The brain’s immune cells work to attack any invaders that are created when these breaches occur.
But one of the new studies presented Wednesday suggests it is increasingly clear that SARS-CoV-2 can also take a different, less-guarded route through the nose, heading straight to the brain. This research by the California National Primate Research Center found that brain neurons in brains of rhesus monkeys who were infected with SARS-CoV-2 within seven days had developed significant signs of infection. This was especially true for diabetic older animals.
A key finding would be that neurons can be infected. These brain cells transmit information via electrical impulses from the brain to other areas of the body. The immune system won’t attack any neurons that are sick because they are essential to the normal functioning of the body.
The virus has ridden on neurons and is now free to roam the brain’s circuitry.
“This is, I believe is a far more dangerous type of infection,” stated John Morrison, who is a professor of neurology and led the research. He said that the virus could travel through the brain’s circuitry and “it can get into multiple brain regions that mediate emotions and moods like cognition, memory, emotion, and mood.” These are the exact issues reported by people who have long Covid. Previous research on neural infections has been mixed and not all experts agree the results are definitive. Dr. Walter Koroshetz (director of the National Institute of Neurological Disorders and Stroke) stated that he was still not convinced that SARS-CoV-2 could infect neurons and that more research is needed.
Dr. Greg Vanichkachorn, an occupational medicine specialist who works with long Covid patients at the Mayo Clinic in Rochester, Minnesota, said brain samples taken from people who died of Covid-19 earlier in the pandemic largely haven’t shown this kind of infection.
But, he added, it is possible that Covid-19 affected those patients in a different way. Not all patients get the same type of illness. It may be that patients with a less severe condition, even if they are afflicted for months, might get infected in a different way.
” “I have felt since very early on in my treatment of patients with this condition, that it’s more then just a respiratory condition,” Vanichkachorn said. These findings are not surprising to me. “
It’s not all in their heads
Another study presented at Wednesday’s meeting, provided additional evidence of neural infection. Researchers at the Rotman Research Institute in Toronto used electroencephalography, or EEG, to measure how well the brain is functioning in terms of its electrical signals.
The study was small, just 41 Covid-positive patients and 14 others who had some symptoms, but ultimately tested negative. They all had mild illnesses and were not hospitalized.
The EEGs revealed brain wave patterns that were different in Covid patients, which lasted at most seven months after their initial infection. Simply put, the brains of Covid patients were not functioning as well or as effectively as those without the disease. Allison Sekuler, who also served as the Institute’s Sandra A. Rotman chair in Cognitive Neuroscience, stated that the EEGs showed different brain wave patterns.
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Sekuler’s research, too, should be considered early and preliminary. And it is unlikely that the new findings can fully explain the types of brain fog and other cognitive issues reported by those with long Covid.
But Sekuler stated that the results so far “clearly demonstrate” months-long changes in brain function. The findings may offer comfort to long-termers who are worried about their loved ones’ doubts regarding ambiguous or ongoing symptoms.
” “It’s very frustrating for many patients,” Vanichkachorn stated. “Patients are often accused of making this up or malingering to get attention. “
Sekuler also dismissed those who claim long Covid symptoms are “just all in a person’s head.”
“Yeah, OK, but that’s because the brain controls everything,” she said, “your sense of smell, your memory, the way you see the world, even the way you feel.”