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Infectious Diseases

21 September 2020

To what extent is Covid-19 damaging the brain?

Scientists are struggling to understand the coronavirus's effect on the brain as more patients present with neurological symptoms.

  • Many neurological symptoms and diagnoses have been documented in Covid-19 patients
  • It's unknown how prevalent these brain disorders are in those infected
  • Scientists are trying to figure out if Covid-19 affects the brain directly, or if inflammation in the immune system is causing the disorders

Maybe it's a bad trip, or maybe it's the "rona". For one woman – hallucinating about lions and monkeys in her home and convinced her husband was someone else – it turned out to be the latter.

And she's not the only one.

Scientists are struggling to understand Covid-19's effect on the brain as more patients present with neurological symptoms. In the beginning of the pandemic, these symptoms were often missed as healthcare workers were more concerned about keeping patients breathing than noticing whether they were "seeing things".

READ | Brain disorders found in Covid-19 patients with mild symptoms 

The research

Scientists have, however, slowly started taking note of neurological disorders in Covid-19 patients. In July, a UK study detailed more than 40 cases of patients presenting with brain dysfunctions like encephalopathy, ischaemic stroke and Guillain-Barré Syndrome, all of which can cause haemorrhaging and inflammation.

These symptoms were even present in patients with mild Covid-19.

Another study also showed how mini-brains grown in a lab proved that viral replication could take place in their cells, signalling potential long-term brain damage, although how the virus would get into the brain remains an unanswered question.

A research paper explained that an infection of the brain could happen in three stages: loss of taste and smell as it infects the nose's epithelial cells; blood clots in the system that could lead to strokes; and damage to the blood-brain barrier by the ensuing cytokine storm, making our most important organ vulnerable to further infection.

Brain haemorrhage and memory loss have also been added to the growing list of brain disorders caused by Covid-19.

READ MORE | Proof that the coronavirus can infect lab-grown brain cells might make its effects felt long-term 

'Scary'

This growing number of neurological symptoms are becoming quite "scary", scientists told Nature. They are not too sure how prevalent the conditions are in the general population, who is at greatest risk of developing these symptoms, or even why it's happening.

Despite the research mentioned earlier, the evidence isn't yet conclusive as to whether it's the virus infecting the brain or if it's a reaction to the havoc caused in the immune system. This is vital to know what treatment to give them, as it can be risky to give medication for the wrong cause.

Experts haven't found the virus in real human brains, or in the spinal cord and fluid that surround the brain. The brain also doesn't have ACE2 receptors, the most popular gateway for the virus into cells, which might lean the debate in favour of the immune system effect.

Common diagnoses

In another 125 unique cases study, 62% suffered from damage to the brain's blood supply, and 31% exhibited altered states of mind, 41% of which was attributed to unspecified encephalopathy and encephalitis. The rest received mostly new psychiatric diagnoses, including new-onset psychosis, dementia-like syndrome and affective disorder. 

Neurological conditions also affected younger patients and didn't necessarily mean that one ended up in the ICU. This means that numbers affected by these symptoms could be unknown, as most studies only focused on patients that were hospitalised. 

But research and clinical trials are currently underway to better understand these brain disorders linked to Covid-19, including tracking recovered patients' progress and sampling spinal fluids, but it could take years to sort through all the data.

READ | Stroke, confusion: Covid-19 often impacts the brain

Image credit: iStock