COVID survivors have been warned the brain could be irreversibly damaged by the virus.
Dozens of studies have shown that the main organ is damaged in even the mildest forms of Covid disease.
There have been reports of “brain fog”, trouble concentrating and memory problems, with some encouraging studies suggesting that most people see improvements within six to nine months.
The new study by Oxford University researchers looked at people in the UK over 50 who had a mild case of Covid.
All 785 participants were in the UK Biobank, a large medical research database, and had two brain scans 38 months apart.
A total of 401 participants had tested positive for Covid between the two scans.
The study found a range of brain effects, an average of 4.5 months after infection.
Covid survivors had greater reductions in gray matter thickness and tissue damage in regions of the brain associated with smell.
They had a reduction in overall brain size and showed a decline in cognitive function after running a battery of tests.
The effects ranged from 0.2 to 2 percent additional change compared to the uninfected participants.
Professor Gwenaëlle Douaud, lead author of the study, said: “Although the infection was mild for 96 percent of our participants, we saw greater loss of gray matter volume and tissue damage in the infected participants.
“They also showed greater declines in their mental abilities to perform complex tasks, and this mental deterioration was partly related to these brain abnormalities.
“All of these negative effects were more pronounced in older age.
“A key question for future brain imaging studies is to see if this brain tissue damage resolves over time.”
It is not clear at this time if the effects on the brain are reversible.
Professor Stephen Smith, senior author of the study, said: “The fact that we have the scan before infection helps us distinguish brain changes related to infection from differences that may already have existed in their brain.”
The evidence is piling up
The study, published in the journal Nature in March, echoes the findings of a number of others.
Researchers at Tulane University last week reported findings based on examining primates used in human similarity studies.
They found severe brain swelling and injury associated with reduced blood flow or oxygen to the brain.
They also found evidence of minor hemorrhages, neuron damage, and death — even in primates that didn’t have a serious illness.
The lead researcher Dr. Tracy Fischer said: “Because the subjects had no significant respiratory symptoms, nobody expected that they would have the severity of the disease that we found in the brain.
“But the findings were clear and profound and undoubtedly a result of the infection.”
Meanwhile, researchers – including those from Imperial College London and Cambridge universities – found that Covid can cause a “significant decline” in intelligence.
The results come from a series of tests of memory, reasoning, planning and problem solving on more than 81,300 people.
People who were on a ventilator during their Covid illness were most likely to see their scores drop.
The team claimed that they would have lost the equivalent of seven points in IQ on a classic intelligence test.
The study states: “These results are consistent with reports of long Covid where ‘brain fog’, difficulty concentrating and difficulty finding the right words are common.
“The deficits had a significant effect size for people who had been hospitalized.”
Another study reassured that “Brain Fog” shouldn’t last more than a year.
Covid patients scored significantly lower on episodic memory and their ability to sustain attention on a task for an extended period of time.
However, Professor Masud Husain of the University of Oxford said it was “encouraging” that most people’s attention and memory “will largely return to normal in six to nine months”.
He said, “We still don’t understand the mechanisms that cause these cognitive deficits.”
A team in the US suggested that brain fog symptoms were the result of a lack of oxygen to the organ.
After the autopsy of Covid victimsScientists at Johns Hopkins University School of Medicine found that large cells called megakaryocytes took up space, leaving less room for blood to flow freely through the brain.
According to Professor James Goodwin, the director of science and research impact at the Brain Health Network, it is assumed Covid invades the brain through tightly occluded blood vessels surrounding the organ.
But there is another explanation, he wrote The telegraphh, and our own immune system is to blame.
Sometimes, in response to a virus, the immune system goes into overdrive and releases too many inflammatory molecules called cytokines.
Known as a cytokine storm, this phenomenon can damage healthy organs, including the brain, as well as the lungs and heart.
It has resulted in the deaths of many Covid victims and those that survive may suffer long-term damage.
The cytokine storm is typically more common in people who are unhealthy, have a long-term illness, are elderly or have a high viral load, Prof Goodwin said.
https://www.thesun.ie/health/8637905/warning-anyone-had-covid-irreversible-damage-brain/ Warning to anyone who has had Covid of ‘irreversible’ damage to the brain