How does coronavirus affect the brain?

July 24, 2020

How does coronavirus affect the brain? And why are people with COVID-19 experiencing delirium? Here's what you need to know.

There’s a common idea that SARS-CoV-2, the coronavirus that causes COVID-19, is a virus that mostly affects the lungs and airways. But it’s now becoming clear that it can affect other parts of the body too, such as the skin and gut.

Data from our COVID Symptom Study app shows that patients with coronavirus frequently suffer from delirium, a state of acute confusion, and disorientation. So can coronavirus affect the brain too?

Increasingly, the evidence is saying ‘yes’, with doctors warning of rare but serious brain disorders triggered by even mild cases of the disease.

In this post, we speak to our consultant geriatrician, Dr. Claire Steves, to find out more about how coronavirus affects the brain, and what you can do to decrease your risk of neurological symptoms.

What is delirium?

Delirium is an acute confusional state that can come in any acute medical illness. And it usually happens in people who have a susceptibility. For example, people with Alzheimer's or dementia, more commonly get delirium. But it also can happen when people have no background problems,” explains Claire.

Claire says that although it hasn’t been widely reported, people with coronavirus often develop delirium. 

"Right at the beginning of the pandemic we noticed just anecdotally that patients with coronavirus were coming in with acute confusion and disorientation." 

Patients have reported terrifying confusion and hallucinations from their time in the hospital being treated with COVID-19. But there hasn't been much research on the neurological effects of the diseases so far.

“Everybody's talking about it, but there are very few research papers,” says Claire. 

To find out more, we included a simple question in our COVID Symptom Study app: ‘Do you have confusion, disorientation, or drowsiness?’. The results were revealing. 

“We found that it is quite a common symptom, especially in frailer older people. Delirium is more common in those that tested positive than those that tested negative for COVID-19,” Claire explains. 

“We also found that if you have delirium, you are more likely to be admitted to hospital with COVID-19, and you are more likely to need respiratory support.” 

Other studies have also found that 20% of people admitted to hospital and 60% of patients in intensive care with COVID-19 suffered from confusion. 

Why are people with COVID-19 suffering from delirium?

“The big question is if people with coronavirus are developing delirium because the virus has a huge effect on the body and the immune system, as we might see with other infections, or is there something more specific with coronavirus and the brain?”

Claire suspects that the SARS-CoV-2 virus, which causes COVID-19, may enter nerve cells in the brain, disrupting them and causing delirium symptoms. 

This idea that coronavirus might attack nerve cells is supported by studies suggesting that loss of smell (anosmia) experienced by some people with COVID-19 is also caused by the virus entering olfactory nerve cells in the back of the nose.

Delirium has also been linked to hypoxia, which is when your body is not getting enough oxygen, which can be related to the lung damage and blood clots caused by the virus. But clinicians have noticed that patients with coronavirus may not show any signs they are hypoxic. 

"Patients would be on their mobile phone looking like they're fine talking away, but actually they're very hypoxic and they deteriorate very rapidly," says Claire.

What factors increase the risk of developing delirium?

"We've looked at the delirium data from twins using the COVID Symptom Study app, and we've seen that delirium symptoms were more likely to be similar between identical twins than non-identical twins,” says Claire.  

When the team analyzed the data more closely, they found that around 50% of the variation between people developing delirium or not when they contract COVID-19 is explained by genes.

"That might mean that there are genes and biological pathways that could explain why some people are more vulnerable to delirium in the context of COVID-19 compared to others,” Claire explains. 

How can we reduce the risk of delirium?

As a doctor who focuses on elderly people, Claire is familiar with the signs of delirium, as well as the things that can help to reduce the risk. Here are her tips:

  1. Stay hydrated - Make sure you’re getting enough fluids, because dehydration is often associated with delirium.
  1. Control blood sugar levels - Unhealthy changes in blood sugar levels are seen in some patients with COVID-19 and can exacerbate delirium. If you have diabetes, you should make sure that you are taking care to control your blood sugar levels. And even if you don’t, it’s a good idea to eat foods that keep your blood sugar responses healthy. 
  1. Keep your digestive system moving - Constipation has been associated with an increased risk of delirium, so make sure you’re eating plenty of fiber (tip: eat more plants!) as well as drinking plenty of fluids to make sure you’re staying regular.

As well as reducing your risk of delirium, taking these actions will also reduce your risk of other severe COVID-19 symptoms. 

"It's all linked, so if you get coronavirus, doing these things will improve outcomes overall," Claire says.

COVID-19 and the brain in a nutshell

  • Delirium is an acute confusional state that is common among people with COVID-19.
  • If you have delirium, you are more likely to test positive for coronavirus, become hospitalized, and need respiratory support.
  • You can reduce your risk of developing delirium and other severe symptoms of COVID-19 by staying hydrated and nourished.
  • Delirium symptoms may indicate that the virus has neurological effects, but we need more research to understand how coronavirus affects the brain. 

To learn more about the neurological effects of COVID-19, we need people to keep tracking their symptoms through the COVID Symptom Study app. If you haven’t already, download the app to get started.

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