A new paper from a time at Yale University, Connecticut, in the US, says that headaches, confusion and delirium experienced by some Covid-19 patients may be the result of the coronavirus directly invading the brain. The preliminary research offers several some additional evidence to support earlier untested theories about long-term effects on some Covid-19 patients.
The novel coronavirus not only targets the lungs (a situation that is now well documented), but also the kidneys, liver and blood vessels. And brain. About 50% of patients report neurological symptoms suggesting the virus is also attacking the brain.
The study, led by Yale immunologist Akiko Iwasaki, reported that the virus is able to replicate inside the brain, and can starve brain cells of oxygen, though the precise mechanisms or prevalence of the phenomenon is not currently clear.
“If the brain does become infected, it could have a lethal consequence.”
Several peer researchers have already commented that the study, released yesterday, was “careful and elegant”, showing in multiple ways that the virus can infect a patient’s brain cells.
The Chairman of the neurology department at the University of California, San Francisco, S Andrew Josephson, has praised the techniques used for the study, but added that he would “remain cautious” until the paper underwent peer review.
“Understanding whether or not there is direct viral involvement of the brain is extraordinarily important.”
Doctors have previously believed that the neurological impacts seen in about half of all Covid-19 patients could instead be the result of an abnormal immune response that causes inflammation of the brain, part of the “cytokine storm”, rather than the virus invading directly.
The Yale experiments approached the question by infecting lab-grown mini-brains known as “brain organoids”, by infecting mice, and by examining the brain tissues of deceased Covid-19 patients. The team discovered that the SARS-CoV-2 virus is able to infect brain neurons and then “hijack” the neuron cell’s machinery and make copies of itself.
“Infected cells in turn promoted the death of surrounding cells by choking their oxygen supply”, according to the report.
They also performed a spinal tap on a Covid-19 patient suffering from delirium finding the individual had neutralising antibodies against the virus in their spinal fluid. They also examined the brains of 3 patients who died from Covid-19 related complications, finding evidence of the virus in the brains of the patients.
“The infected regions did not show signs of having been infiltrated by immune cells, such as T-cells, which rush to the site of other viruses like Zika or herpes to kill the infected cells.”
The report suggested that this could hint that the overloaded immune response known as cytokine storm which is responsible for much of the damage seen in the lungs of Covid-19 patients, might not be the main cause of neurological symptoms.
Researchers believe that the virus may be getting into the brain through the nose, or through the eyes or even from the bloodstream.
“It’s unclear which route the pathogen is taking, and whether it does so often enough to explain the symptoms seen in people.”
SOURCE: AFP | New York Times
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