Confusion, stroke, memory loss: How coronavirus affects brain

Confusion, loss of smell, behavioural changes -- These are some of the neurological symptoms of the novel coronavirus as witnessed in Covid-19 patients lately.

Some people, hospitalised with Covid-19, experience delirium -- they are confused, disorientated and agitated. Stroke, brain haemorrhage and memory loss are some other serious impact coronavirus has on few patients.

Robert Stevens, MD, Johns Hopkins University, estimated that at least half of the patients he's seeing in the Covid-19 units have neurological symptoms. However, scientists are struggling to understand why the brain may be harmed due to the virus.

A Johns Hopkins article, authored by Robert Stevens, listed some of the theories by scientists who are researching on the subject.

According to the article, several Covid-19 cases across the world can have a variety of conditions related to the brain. These include confusion, loss of consciousness, seizures, stroke, loss of smell and taste, headaches, trouble focusing and changes in behaviour.

Less common peripheral nerve issues, which may lead to paralysis and respiratory failure, have also been noticed among some Covid patients. Similar symptoms have been seen in outbreaks such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), also caused by coronaviruses, a report in a leading science journal said.

HOW CORONAVIRUS AFFECTS BRAIN?

The Johns Hopkins article mentions four ways, based on current research, how Covid-19 may harm the brain. It specified that each "needs to be studied rigorously before any conclusions can be made".

Severe infection: "The first possible way is that the virus may have the capacity to enter the brain and cause a severe and sudden infection," the article read.

It further said that some cases reported in China and Japan found the "virus's genetic material in spinal fluid, and a case in Florida found viral particles in brain cells. This might occur due to the virus entering the bloodstream or nerve endings."

According to the article, the loss of smell that occurs in some Covid-19 patients could indicate that the "virus entered through the olfactory bulb, which is located right above the nose and communicates information about smell to the brain".

Immune system: The immune system is affected in an attempt to fight the novel coronavirus, producing a "maladaptive" inflammatory response that may cause much of the tissue and organ damage seen in this disease.

Physiological changes: The physiological changes induced in the body by coronavirus -- ranging from high fevers to low oxygen levels to multiple organ failures -- contribute to, or account for, brain dysfunction, such as the delirium or coma seen in many of the severe Covid-19 patients.

Stroke: The blood-clotting system in Covid-19 patients with illness is highly abnormal. Clots are much more likely to occur in these patients than in others. "Clots can form in veins deep inside the body or in the lungs, where they can cut off blood flow. A stroke could occur if a blood clot were to block or narrow arteries leading to the brain."

HOW COMMON IS BRAIN DAMAGING IN COVID PATIENTS | STUDIES

According to a study published in The Lancet, a research was conducted with a sample size of 125 Covid patients in the UK who had neurological or psychiatric effects.

According to the results, 62 per cent of the sample size had experienced damage to the brain's blood supply, such as strokes and haemorrhages, and 31 per cent had altered mental states, such as confusion or prolonged unconsciousness - sometimes accompanied by encephalitis, the swelling of brain tissue.

Ten people, who had altered mental states, developed psychosis.

"Not all people with neurological symptoms have been seriously ill in intensive-care units," the study revealed.

A similar study was published in July compiled detailed case reports of 43 people with neurological complications from Covid-19. ()

According to Michael Zandi, a neurologist at University College London and a lead author on the study, the most common neurological effects are stroke and encephalitis.

The study revealed that some of the worst-affected patients had only mild respiratory symptoms. "This was the brain being hit as their main disease," says Zandi.

A report quoted Alysson Muotri, a neuroscientist at the University of California, San Diego, in La Jolla, as saying: "The neurological symptoms are only becoming more and more scary," says .