How Covid-19 can damage the brain

Not only does Covid-19 damage the lungs, heart and kidneys, it can also cause severe brain damage – with patients suffering neurological conditions including paranoia and hallucinations, a British scientific study has revealed.

A model of SARS-CoV-2, known as the novel coronavirus, is seen ahead of a U.S. Senate Appropriations subcommittee hearing on the plan to research, manufacture and distribute a coronavirus vaccine, known as "Operation Warp Speed", on Capitol Hill in Washington, D.C, U.S, July 2, 2020.
A model of SARS-CoV-2, known as the novel coronavirus, is seen ahead of a U.S. Senate Appropriations subcommittee hearing on the plan to research, manufacture and distribute a coronavirus vaccine, known as "Operation Warp Speed", on Capitol Hill in Washington, D.C, U.S, July 2, 2020. © Saul Loeb, Reuters

Following her discharge from hospital after being treated for symptoms of Covid-19, a 55 year-old British woman started hallucinating, seeing monkeys and lions in her house. She started suffering from a persecution complex, and was possessed by a compulsion to repeatedly take off and put on her coat.

She was one of 43 patients with severe neurological complications from Covid-19 studied by British scientists, for a study published on July 8 in the neurological publication Brain. This report reinforced the growing scientific consensus about the severe brain damage the coronavirus can cause.

“We had to wait for the virus to come over to Europe from China before scientists in Italy could tell us about its neurological effects,” said Pierre-Marie Lledo, director of the Department of Neuroscience at the Institut Pasteur, the renowned medical research centre in Paris. At the outset of the pandemic, the first salient finding in this domain was the loss of taste and smell amongst those suffering from the coronavirus.

‘Repercussions on the brain’

The new study “makes it possible to the see more clearly the kind of neurological damage Covid-19 causes”, Lledo noted. There is a wide variety of problems it creates. The British scientists behind the Brain study have found that it can provoke strokes, different types of encephalitis, ADEM (an acute inflammatory disease of the central nervous system that usually affects children), and Guillan Barré syndrome (a condition that attacks the nervous system and causes paralysis).

These complications – which only seem to affect a small number of those infected with the virus – can occur up to six days before and 14 days after the onset of the more common Covid-19 symptoms such as a dry cough or fever.

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These findings suggest that Covid-19 has a “neurotropic inclination, meaning that it attacks neurons”, Lledo continued. The best-known neurotropic virus is rabies, which attacks the central nervous system almost exclusively. The fact that Covid-19 is primarily a respiratory illness in no way prevents it from having this neurological aspect.

“We know that the receptor which allows Covid-19 to enter cells is present in the respiratory tract, but it is also present in cells of other organs, such as the brain and liver,” said Nicholas Locker, a professor of virology at the University of Surrey. “It’s quite common for a virus to be able to migrate, so it’s not surprising that Covid-19 causes brain damage,” he continued.

Covid-19 is not the first case of a virus that attacks the brain. One of previous pandemics to take the world by storm, the 1918-19 Spanish flu, caused serious neurological complications. Similarly, the Zika virus, which travels through the blood, has been shown to cause forms of brain damage such as microcephaly. During previous pandemics of coronaviruses – such as SARS in 2002 and MERS in 2012 – “there were signs of repercussions on the brain, although not enough” for a sufficiently clear picture, Lledo said.

Possibility of ‘chronic’ consequences

What surprised the British researchers was that, for some of the hospitalised patients, “the pulmonary symptoms were relatively weak, while the neurological symptoms were severe”, Lledo said. This was notably the case for a woman in her sixties, already suffering from symptoms of cognitive decline, who was admitted to the hospital after a series of hallucinations. The damage to her brain was worse than the damage to her lungs.

However, the British study doesn’t give any indications as to whether people who are asymptomatic or are showing only mild symptoms risk developing serious neurological complications. “The researchers were looking specifically at what was happening in patients who were already very ill,” Locker said. The sample size was also too small to allow scientists to make an assessment on this point.

The fact that some of these patients developed neurological complications up to two weeks after the onset of symptoms of Covid-19 suggests that “we’ll need to monitor patients more closely after they’ve hospital to take this risk into account”, Locker noted.

The study also called for further investigations into the effects of Covid-19 on the brain. Locker argued that it would be necessary to find out if “Covid-19 symptoms are worse for people who are likely to develop neurodegenerative diseases”.

In doing so, scientists would determine whether or not such people should be included in group sheltered from the virus because of their elevated health risks, such as those with diabetes and respiratory diseases.

The great fear this study raises is the possibility that “Covid-19 could have chronic neurological consequences”, Lledo said. He noted that, “for reasons that are still mysterious to us, certain symptoms of Covid-19 seem to recur in some people”. Notably one of the main risks – currently being examined in pan-European research – is that the coronavirus can trigger chronic fatigue syndromes.

This article was adapted from the original in French.


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