An early study reveals that SARS-CoV-2 can infiltrate brain cells undetected if it enters by the nose, resulting in long-term neurological symptoms such as memory and thinking difficulties.
There are two new studies one from the California National Primate Research Center and another from the Rotman Research Institute that demonstrate that the virus directly infects neurons within the brain, which could explain why some people experience a wide range of symptoms even after their original Covid infection has passed.
Studies presented at the Society for Neuroscience meeting Wednesday were neither peer-reviewed nor designed to provide a comprehensive response to every question regarding the long Covid.
Nonetheless, they come at a time when researchers around the world are scrambling to learn more about a mysterious and debilitating illness that is estimated to affect at least one-third of the more than 46 million people who have been afflicted in the United States, as well as millions more globally.
Covid, a disease that has thus far escaped definitive diagnosis, prognosis, and treatment, can be defused by focusing on how the virus invades and affects the brain.
Things like viruses are normally prevented from entering the brain by the body’s natural blood-brain barrier, although this is not always the case. SARS-CoV-2 and other viruses, including viral encephalitis and HIV, are capable doing this. Immune cells in the brain respond to these breaches by launching an attack on the intruder.
New studies presented Wednesday reveal that SARS-CoV-2 can use a less-guarded pathway through the nose, which leads directly to the brain.
Research from the California National Primate Research Center discovered that monkeys infected with the virus had considerable indications of infection in their brain neurons just seven days after exposure. Older, diabetic animals were the most susceptible to this type of problem.
Key findings would include evidence that neurons can become infected. A kind of brain cell that transmits electrical impulses to different regions of the body from the brain. In order to keep the body’s functions running smoothly, the immune system avoids attacking even damaged neurons.
It is possible for the virus to roam about the brain’s circuitry once it has taken a ride on neurons.
“This, I believe, is a much more dangerous kind of infection,” says the study’s lead author John Morrison.
If the virus can reach the brain’s circuitry, he added, “it can get to multiple brain regions that mediate things like cognition and memory, and emotion and mood.”
Those are exactly the problems that patients with a long Covid report so frequently.
Additional evidence of neural infection was presented at the meeting on Wednesday. Electroencephalography, or EEG, was applied by researchers at the Rotman Research Institute in Toronto to determine how effectively the brain was operating in terms of electrical signals.
It was a small trial, with just 41 Covid-positive patients and 14 others who showed some symptoms, but were ultimately negative. All of the patients had minor ailments and were not hospitalized.
The EEGs of the Covid patients showed distinct brain wave patterns that lasted at least seven months after their first infection.
Allison Sekuler of the Institute for Cognitive Neuroscience, who directed the study and serves as the Sandra A. Rotman Chair in Cognitive Neuroscience claimed that on average their brains were less efficient or productive than those without Covid.
Sekuler’s research, too, should be regarded preliminary and in its early stages. Furthermore, the new findings are unlikely to explain the types of cognitive impairments described by patients who have had a long Covid history.
It’s not certain how long these changes in brain function will last, but Sekuler says they are “clearly show.” If the findings are confirmed in future studies, long-haulers whose loved ones may be suspicious about persisting, confusing symptoms could be comforted by the findings.
“It is very frustrating for many of my patients” who say they have family members who don’t believe that Covid exists in the first place, said Dr. Greg Vanichkachorn, an occupational medicine specialist who works with long Covid patients at the Mayo Clinic in Rochester, Minnesota.
“Patients often get accused of malingering or making this all up for 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.”
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