New studies have revealed more about the damaging effects of Covid-19 on the human brain.
Professor of neurology and Director of the Institute of Infection and Global Health at the University of Liverpool, Professor Tom Solomon, has co-authored a UK-wide study published in Lancet Psychiatry, and also an international study Brain Infections Global investigating the breadth of Covid-19's complications on the brain.
There has been evidence of neurological complications even after a mild bout of what has been referred to since the start of the pandemic as a respiratory disease.
Some people have reported problems with memory and tiredness, and there are more serious concerns about more severe repercussions including stroke, confusion and anxiety.
Dr Solomon tells Lynn Freeman that one of the more surprising neurological problems they are seeing is stroke.
“Initially the focus with Covid-19 was on the lungs. It is clearly a respiratory pathogen. but what we’ve seen as the outbreak’s gone on is more and more cases of neurological diseases, brain disease.
“And we’ve written up some of these patients in the last few weeks. In particular, we wrote up our first 150 or so from the UK to describe what we were seeing.
“What we are seeing is this virus causes a range of brain problems, perhaps one of the most important and most surprising is stroke.”
The reasons for this are unclear, he says.
“It seems to increase the risk of stroke for reasons that are not yet clear, so we’re seeing stroke, we’re also seeing delirium, which is when a patient is confused.
“All breathing viruses and breathing diseases can do that, but we are seeing more of it with this virus than we would expect. And we’re also seeing evidence sometimes that the virus might have got into the brain itself and be causing inflammation there, a condition called encephalitis.”
UK-wide study reported brain complications in 150 coronavirus patients, half of which have had a stroke. Others had brain inflammation, psychosis, or dementia-like symptoms.
An international study Brain Infections Global investigating the breadth of Covid-19's complications on the brain, is also underway.
“What we’re now doing is a much bigger study where we’ve gone back to everyone who has published a paper and said let’s collect the data in a consistent way so that we can compare from all the different places were we’re seeing this.”
He says data from 2500 patients around the world has already been gathered.
So far the data indicates older patients are more likely to have a stroke, while there is an increased incidence of psychiatric problems among younger patients – such as delirium.
He says this is a cause for concern.
“I think this is worrying, we know this virus damages the lungs, most people who have a respiratory infection will make a full recovery from that.
“With the brain it’s different. Once the brain is damaged the brain can’t usually get fully back to normal and so this is leaving some people with long-term problems.”
The virus seems to make the blood stickier, he says.
“Stroke is a blockage of a blood vessel usually, that’s the most common cause, and then the brain tissue that is supplied by that blood vessel dies and that’s what a stroke is.
“In the normal population the risk of a stroke is increased in people who are smokers or who have high blood pressure or diabetes. Covid-19 seems to provide an additional risk factor on top of those risk factors.
“In severe infections the virus seems to make the blood more likely to clot, more sticky.”
Neurological presentations have ranged from poor memory, to concentration problems and anxiety and depression, Dr Solomon says.
“This is a new virus, we have only known about it since the end of December so we are really feeling our way.
“To begin with, with any of these neurological presentations, the initial approach was just to manage the patients as we would normally manage someone with stroke or normally manage someone with delirium or encephalitis.”
Now the research will focus on whether there are differences among Covid patients, he says.
Covid-19 is behaving like SARS 1 and MERS did, he says.
“It’s causing encephalitis, it’s casing myelitis, damage in the spinal cord, it’s causing peripheral nerve problems as well Guillaine-Barre syndrome
“I think it’s behaving a bit more like a coronavirus than the 1918 flu virus in terms of the types of neurological problems that it’s causing.”
He says the level of international cooperation has been very strong.
“We’ve had a fantastic response, and one of the striking things about this pandemic is the way the world scientific community has pulled together, sharing data very readily, publishing results as soon as we have them.
“For our international study now we have 77 countries contributing data it’s pretty much everywhere that there’s been any patients.”
He advises medical practitioners and patients in New Zealand to monitor post Covid recovery.
“Some people who apparently just had a respiratory problem and then got out of hospital and you would hope would get back completely to normal - some of these people are having anxiety and depression.
“Does that just relate to the fact they’ve been ill and maybe they’re in some kind of lockdown? Or is this virus causing problems beyond just the usual problems of being unwell?”
The data being collected through the Covid-19 Brain Infections Global network will give a better chance of answering those questions, he says.