The fatigue it is the best known consequence of Covid 19. An unnatural exhaustion, which can last for days or weeks even after being healed. But this is not the only aftermath of the disease. Problems with memory and reasoning – the so-called brain fog, a cognitive fog that seems to dull the mind – are emerging more and more often in the scientific literature, with an increasing number of patients suffering from it even months after the infection. And a new study from the University of Cambridge helps today to better understand the proportions of the problem: for some of the most at-risk patients, those who have suffered from a severe form of Covid 19, it is as if the brain had suddenly aged over 20 years.
Long Covid and Brain
The cognitive sequelae of Covid are one of the aspects of this pandemic that is receiving the most attention in recent months from the public and the scientific community. The legacy of this virus that we have to deal with in these months when the epidemic seems to loosen its grip, at least in terms of hospitalizations and deaths. In fact, many patients continue to complain of symptoms even at the end of the infection: sleep problems, memory, reasoning, anxiety disorders and other psychiatric symptoms. In England, nearly 13% of patients appear to be suffering from one or more of these problems within three months of recovery. But for those who have suffered from a form severe enough to need hospitalization, things seem to be even worse: between 33 and 76% of former patients are talking about cognitive problems up to 6 months after being healed. .
Being mostly statistics collected on subjective evaluations of patients, the Cambridge researchers decided to try a more objective verification of the prevalence and severity of symptoms. To do this, they assessed the cognitive abilities of 46 former patients hospitalized for Covid 19 in the UK using Cognitron, an online platform developed by Imperial College London. The participants were carefully tested six months after the war, and the results were compared with those of 460 volunteers who did not contract Covid, and with the average results calculated on over 66 thousand people who have taken the test in the past.
10 points of IQ
In this way, the researchers believe they have obtained a credible assessment of the cognitive effects experienced by those who develop Covid in an acute form. On average, critically ill ex-patients performed particularly poorly in aspects such as analog verbal reasoning (the ability to find similarities and relationships between words) and reasoning speed. The effects – the researchers write on eClinicalMedicine – are comparable to those seen in 20 years of brain aging between the fiftieth and seventieth years of life. Or even a net loss of 10 points of IQ.
“Cognitive impairment is a problem common to a wide range of neurological disorders, such as dementia and even normal brain aging, but the pattern we observed – the Covid 19 fingerprint – is completely different from any other,” he explains. David Menon, Cambridge anesthetist who coordinated the research. “Some patients were able to follow them up to 10 months after acute infection, and therefore I can say that we have observed some slow improvement – he adds – nothing significant from a statistical point of view, but still a step in the right direction. As far as we know at the moment, however, some of these patients may never make a full recovery. “
A known problem
As we said, the cognitive consequences of Covid 19 are an increasingly studied field in recent months. A study published in preprint in March on Nature for example, it looked at brain scans of 401 people aged 51 to 81 who contracted SARS-Cov-2 in the UK, comparing them with those of 384 who did not have the disease. The analysis made it possible to verify the brain anatomy of the participants both before and after the disease, demonstrating the presence of important changes, in particular in the thickness of the gray matter and in the total volume of the brain. Also testing the cognitive abilities of the participants, the study revealed a decline in those affected by Covid 19, related to the morphological changes that emerged from brain scans.
Another recent study, published in Jama Neurology, instead, investigated the link between Covid and the development of dementia. The research involved over 1,400 patients from Wuhan (the Chinese city where the disease first emerged), all over 60, testing the cognitive abilities of patients 6 and 12 months after the war. In patients who had suffered from severe Covid the risk of early-onset dementia was 4.87 times higher than that of non-infected. And even for those who had developed a mild form, the problem was still 1.71 times more common than normal. Results that, according to the authors of the study, “show that the pandemic in the future will contribute to worsening the burden of dementia in the world“.