After the researchers’ video briefing, the question that arises is: How stupid has Corona made us? A sensational answer could be: Help, Covid-19 lowers the IQ. However, such a short version would not be serious, even if the impression currently arises that the pandemic has damaged the level of many debates. So back to what Adam Hampshire and Paul Elliott were actually able to prove with their extensive study: The scientists from Imperial College London show that cognitive impairments and memory impairments can occur after a corona infection – although these deficits are comparatively small.
The Results from brain researchers and epidemiologists are currently in New England Journal of Medicine appeared. The bad news, according to which impairments in brain function were evident in the 112,000 test subjects, is countered by the good news: the changes are so small that the individual would hardly notice them. Statistically, however, they are definitely noticeable with such a large number of participants.
“There are two other positive messages,” says Paul Elliott. “In the early phase of the pandemic, i.e. with infections with the wild type or the alpha variant, the effects on memory and thinking skills were worse. Like many other things, this has improved significantly with Omicron.” It has also been shown that in the small group in which the Covid symptoms persisted even after twelve weeks, the cognitive limitations subsided as soon as the symptoms associated with Corona improved. Those affected by Long Covid can therefore expect fewer impairments over time. “This is reassuring news,” said Elliott. “Once the chronic symptoms resolve, the cognitive deficits are comparable to those seen in people with a very short duration of illness.”
As a further finding, the researchers were able to demonstrate that a stay in the intensive care unit had the greatest negative impact on cognition and memory. “However, it has long been known that cognitive losses often occur after periods of intensive care,” emphasizes Adam Hampshire, the first author of the study. Whether after an accident, heart attack or stroke – the invasive therapies, ventilation and the temporary loss of consciousness apparently have a negative effect on the brain, although the exact mechanism has not yet been elucidated.
The discrete limitations of the subjects in the study were not based on self-reports, but were recorded by having the participants solve eight different tasks online. This meant that not only memory, but also spatial orientation, expressiveness and comprehension could be assessed. The risk of greater deficits in these areas increased with a longer duration of illness, infection with early virus variants of Sars-CoV-2 and if an inpatient stay was necessary due to the course of the corona. Scientists do not know the exact mechanisms as to why the brain structures are affected at all. “We just don’t know,” said Elliott. “There is speculation about possible markers and accelerated changes. And there is probably not just one factor involved.”
“Compared to the early phases of the pandemic, fewer people are now suffering from persistent symptoms”
The neuroresearchers from London emphasize that they did not conduct any IQ tests on the participants. If one were to transfer the results of the cognition tasks to an appropriate scale – although this is fraught with great inaccuracy – the result would be a loss of around three IQ points. “Such minimal differences would not be noticed by the individual,” says Elliott. “These are small differences between the groups.” If all the unfavorable factors came together, the cognitive impairment would add up to minus five or minus six IQ points, but this would not be associated with any change relevant to everyday life. When asked what the oft-mentioned “brain fog” was all about, Adam Hampshire replied: “Although the term is very much in the general consciousness because it has been reported so much, we actually don’t really know what it is based on our findings that is.”
For Germany, the AOK Scientific Institute has just announced that the number of sick notes following a Covid-19 infection due to Long Covid or chronic fatigue syndrome was “significantly lower” in 2023 than in 2021 and 2022. The peak number of sick notes in this regard was in March 2022 it was 416 out of 100,000 employees, i.e. 0.416 percent. In December 2023 it was 110 out of 100,000 insured people, i.e. 0.11 percent.
“The potential long-term effects of Covid-19 on the brain and memory have been of great concern to doctors, politicians and the public, and have been difficult to assess objectively,” says Hampshire. “Now we have better insights.” For Paul Elliott, there are also positive developments: “Compared to the first phases of the pandemic, fewer people are now suffering from persistent symptoms and cognitive abilities are less likely to be impaired,” said the epidemiologist. When asked whether there was any reason to be concerned given the comparatively small differences between infected and non-infected people, Elliott replied: “So many people have been infected and we don’t know what the long-term consequences are – that’s why we will continue to use the clinical approach Keep an eye on the course and the effects on the brain.”