In the most severe cases, the impact of the disease on cognitive abilities could be equivalent to 20 years of brain aging.
Since the Covid-19 pandemic broke out at the very end of 2019, the effects of the disease have been widely documented by scores of studies conducted by laboratories around the world. Among these symptoms, we find in particular cognitive disorders which occur mainly in the most severe cases. By taking a closer look, a team of researchers determined that this cognitive damage could be much greater than expected.
To reach this conclusion, researchers at the prestigious Imperial College in London conducted a large study that was particularly interested in patients with a so-called form of “severe”. These all had a cluster of acute symptoms, especially at the respiratory level. Some of them, for example, had to be placed on respiratory assistance during the protocol.
A study as rigorous as it is worrying
In total, this work involved a total of 506 patients, including 46 with severe forms. The other 460 served of control group. Lwas then compared to results from more than 66,000 patients to confirm the robustness of the results. It is therefore very well documented work, which is among the most rigorous on the question of the cognitive impact of Covid-19. And unfortunately, their findings are quite worrying.
By statistically comparing the evolution of their cognitive abilities over the course of the disease using the Cognitron platform, the researchers observed a clear trend after six months. After this time, the 46 patients suffering from a severe form had all undergone cognitive impact equivalent to 20 years of brain aging (between 50 and 70 years).
The researchers claim that this corresponds to a loss of about 10 IQ points. This metric in particular is obviously debatable. But this analysis is also verified with much more concrete parameters. Overall, affected patients had, among other things, a slower reaction time and a loss of overall accuracy.
The researchers’ statement also explains that survivors of severe forms obtained particularly worrying scores in tasks such as “verbal analogical reasoning”. In practice, this means they had more difficulty finding their words.
“The cognitive imprint” of Covid-19 persists over the long term
Another important element of this work: the large number of patients included in this study made it possible to statistically isolate the neurological effects of Covid-19. The researchers have identified a set of patterns that clearly show that it is a consequence of this disease, and not the simple effects of aging or the onset of Alzheimer’s, for example.
“Cognitive problems are common to many neurological disorders, such as dementia, and even normal aging. But the patterns we spotted – the cognitive “fingerprint” of Covid-19 were distinct from all of these cases.”, explains David Menon, professor at Cambridge and lead author of the study.
Finally, and this is the most worrying thing, the researchers were unable to determine to what extent this cognitive damage was reversible, even nearly a year after infection. “We followed patients up to ten months after their severe infection”, explains Menon. “We found a very slow improvement, which was not statistically significant”, he indicates.
This observation has at least the merit of showing that the disease generally evolves “in the right direction”. But by the researcher’s own admission, “it is quite possible that some of its individuals will never fully recover”.
A discreet public health problem, but with serious consequences
The exact cause of this damage, however, is still unclear. In their press release, the researchers explain that they are probably the result of a combination of factors. They thus quote pell-mell “inadequate oxygen supply to the brain, blockage of small blood vessels by clotting, microbleeding“, and “the inflammatory response of the immune system”.
For researchers, therefore, there is “urgency to study what can be done to help these people”. And it is difficult to contradict them. Because even if the consequences of the pandemic are no longer so perceptible today, there are still tens of thousands of patients who have suffered from acute forms of Covid-19 since the start of the pandemic.
As many people who, according to this work, could all suffer from long-term cognitive impairment. But to hope to remedy this, it will already be necessary to determine their exact physiological origin. A company that already promises to be excessively complicated. In any case, one thing is certain: we have not finished hearing about this damn pandemic.