According to a team of scientists, the cognitive impairment resulting from severe COVID-19 is similar to that suffered from 20 years of aging between 50 and 70 years and is equivalent to a loss of 10 IQ points.
Cognitive impairment from severe COVID-19 is similar to that suffered between the ages of 50 and 70 and is equivalent to losing 10 IQ points, said a team of scientists from the University of Cambridge and Imperial College London.
The findings, recently published in the journal eClinicalMedicine, come from the National Institute for Health and Care Research (NIHR) COVID-19 BioResource. The results of the study show that the effects can still be detected more than six months after the acute illness and that any recovery is at best gradual.
“Cognitive impairment is common in a wide range of neurological disorders, but the models we saw – the cognitive” fingerprint “of COVID-19 – were different from all of these.” – David Menon
There is growing evidence that COVID-19 can cause long-term cognitive and mental health problems, with recovering patients reporting symptoms including fatigue, brain fog, difficulty remembering, sleep disorders, anxiety and even post-traumatic stress disorder (PTSD). . ) months after infection. In the United Kingdom, a research study found that one in seven people reported having symptoms such as cognitive impairment 12 weeks after passing a COVID-19 test.
While even mild cases can lead to persistent cognitive symptoms, between one-third and three-quarters of hospitalized patients report still suffering from cognitive symptoms three to six months later.
To investigate this relationship in more detail, the researchers analyzed data from 46 people who received inpatient care for COVID-19 at Adenbrook Hospital, part of the Cambridge University Hospitals NHS Foundation Trust. During their hospital stay, 16 patients were placed on mechanical ventilation. All patients were admitted between March and July 2020 and were employed by NIHR COVID-19 BioResource.
Individuals underwent detailed computerized cognitive tests an average of six months after their acute illness, using the Cognitron platform, which measures various aspects of mental ability such as memory, attention and reasoning. Scales for measuring anxiety, depression and post-traumatic stress disorder were also assessed. Their data were compared with matching controls.
This is the first time that such a rigorous assessment and comparison has been made of the consequences of severe COVID-19.
Survivors of COVID-19 were less accurate and slower to respond than the matched control population – and these deficiencies were still detected when patients were followed up six months later. The effects are strongest for those who need mechanical ventilation. Comparing patients with 66,008 members of the general public, the researchers estimated that the rate of cognitive loss was on average similar to that maintained at age 20, between age 50 and age 70, and that this was equivalent to a loss of 10 IQ points. .
Survivors have performed particularly poorly on tasks such as verbally similar reasoning, a finding that supports the often reported problem of difficulty finding words. They also showed slower processing speeds, consistent with previous post-COVID-19 observations of reduced brain glucose consumption in the anterior parietal network of the brain, responsible for attention, problem solving, and working memory, among others. functions.
Professor David Menon of the Department of Anesthesia at the University of Cambridge, a senior author of the study, said: “Cognitive impairment is common in a wide range of neurological disorders, including dementia and even routine aging, COVID-19 – was different from all these. “
Although it is well established that people who have recovered from severe COVID-19 can have a wide range of symptoms of ill mental health – depression, anxiety, post-traumatic stress disorder, low motivation, fatigue, low mood and poor sleep – The team found that the severity of acute illness is better at predicting cognitive deficits.
Patients’ outcomes and response times have begun to improve over time, but researchers say any recovery in cognitive ability is gradual at best and is likely to be influenced by a number of factors, including the severity of the disease and its neurological or psychological effects.
Professor Menon added: “We followed up on some patients up to ten months after their acute infection, so we can see a very slow improvement. Although this is not statistically significant, it is at least going in the right direction, but it is very possible that some of these people will never fully recover. “
There are several factors that can cause cognitive deficits, researchers say. Direct viral infection is possible, but unlikely to be the root cause; instead, a combination of factors are more likely to contribute, including insufficient oxygen or blood supply to the brain, blockage of large or small blood vessels due to clotting, and microscopic hemorrhage. However, emerging evidence suggests that the most important mechanism may be damage caused by the body’s own inflammatory response and immune system.
While this study looks at hospitalized cases, the team says that even those patients who are not sick enough to be admitted may also have signs of mild impairment.
Professor Adam Hampshire of the Department of Brain Science at Imperial College London, the first author of the study, said: “About 40,000 people have gone through intensive care with COVID-19 in England alone and many others will be very ill but not admitted. hospital. This means that there are a large number of people who still experience knowledge problems many months later. We urgently need to look at what can be done to help these people. “
Professor Menon and Professor Ed Bullmore of the Cambridge Department of Psychiatry are jointly leading working groups as part of the COVID-CNS Clinical Neuroscience Study (COVID-CNS), which aims to identify biomarkers associated with neurological impairment as a result of COVID- 19, and the changes in neuroimaging that are associated with them.
Reference: “Multiple profiles and correlates of the acute phase of cognitive deficits in a hospitalized cohort with COVID-19” by Adam Hampshire, Doris A. Chatfield, Ann Manctelow MPhil, Amy Jolie, William Trender, Peter J. Helier, Martina Del Giovanni, Virginia FJ Newcombe, Joanne G. Outtrim, Ben Warne, Junaid Bhatti, Linda Pointon, Anne Elmer, Nyarie Sithole, John Bradley, Nathalie Kingston, Stephen J. Sawcer, Edward T. Bullmore, James B. Rowe , David K. Menon, the Cambridge NeuroCOVID Group, NIHR COVID-19 BioResource and Cambridge NIHR Clinical Research Facility, April 28, 2022, eClinicalMedicine.DOI: 10.1016 / j.eclinm.2022.101417
The study was funded by the NIHR BioResource, the NIHR Cambridge Biomedical Research Center and the Addenbrooke Charitable Trust, with support from the NIHR Cambridge Clinical Research Facility.
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