Severe cognitive impairment due to COVID-19 equivalent to 20 years of age

Summary: Severe COVID-19 infection causes cognitive impairment similar to that sustained by natural aging between the ages of 50 and 70, and is equivalent to losing 10 IQ points.

Source: Cambridge University

Cognitive impairment as a result of severe COVID-19 is similar to that sustained between the ages of 50 and 70 and is the equivalent of losing 10 IQ points, according to a team of scientists at the University of Cambridge and ‘Imperial College London.

The findings, published in the journal Eclinical medicine, arise from NIHR’s COVID-19 BioResource. The results of the study suggest that the effects are still detectable more than six months after the acute illness and that any recovery is, at best, gradual.

There is growing evidence that COVID-19 can cause lasting cognitive and mental health problems, with recovered patients reporting symptoms such as fatigue, “brain fog,” memory problems, sleep disorders, anxiety, and even disorder. post-traumatic stress disorder (PTSD) months later. infection. In the UK, one study found that around one in seven people surveyed reported having symptoms that included cognitive difficulties 12 weeks after a positive COVID-19 test.

Although even mild cases can cause persistent cognitive symptoms, between one-third and one-third of hospitalized patients report that they still experience cognitive symptoms three to six months later.

To explore this link in more detail, the researchers analyzed data from 46 people who received hospital care, in the ward or in the intensive care unit, for COVID-19 at Addenbrooke Hospital, part of the Cambridge University Hospitals NHS Foundation. 16 patients received mechanical ventilation during their hospital stay. All patients were admitted between March and July 2020 and were recruited to the NIHR’s COVID-19 BioResource.

Individuals underwent detailed computerized cognitive testing an average of six months after their acute illness using the Cognitron platform, which measures different aspects of mental faculties such as memory, attention, and reasoning. Scales measuring anxiety, depression, and post-traumatic stress disorder were also evaluated. Their data were compared with matching controls.

This is the first time such a rigorous evaluation and comparison has been made in relation to the subsequent effects of severe COVID-19.

COVID-19 survivors were less accurate and with slower response times than the matched control population, and these deficits were still detectable when patients were followed up six months later.

The effects were stronger for those who needed mechanical ventilation. When comparing patients with 66,008 members of the general public, the researchers estimate that the magnitude of cognitive loss is similar, on average, to that sustained at 20 years of age, between 50 and 70 years, and that this is equivalent to losing 10 IQ. points.

Survivors scored especially low on tasks such as verbal analogical reasoning, a finding that supports the commonly reported problem of difficulty finding words. They also showed slower processing speeds, which align with previous observations after COVID-19 decreased brain glucose consumption within the frontoparietal network of the brain, which is responsible for attention, complex problem solving, and working memory, among other functions.

Professor David Menon of the University of Cambridge’s Anesthesia Division, lead author of the study, said: “Cognitive impairment is common in a wide range of neurological disorders, including dementia and even aging. routine, but the patterns we saw: the cognitive ones. the “fingerprint” of COVID-19: it was different from all of them. ”

Although it is now well established that people who have recovered from severe COVID-19 disease may have a wide range of symptoms of poor mental health: depression, anxiety, post-traumatic stress, low motivation, fatigue, mood swings. ‘low mood and sleep disorders, the team found that the severity of the acute illness was better for predicting cognitive deficits.

Patient scores and reaction times began to improve over time, but researchers say that any recovery in cognitive faculties was, at best, gradual and likely influenced by a number of factors, such as now the severity of the disease and its neurological or psychological impacts.

Professor Menon added: “We followed some patients for up to ten months after their acute infection, so we could see a very slow improvement. Although this was not statistically significant, at least it is going in the right direction. but it is very possible that some of these individuals will never fully recover. ”

There are several factors that could cause cognitive deficits, the researchers say. Direct viral infection is possible, but is unlikely to be a major cause; instead, a combination of factors, such as an inadequate supply of oxygen or blood to the brain, blockage of large or small blood vessels due to clotting, and microscopic bleeding, are more likely to contribute. However, emerging evidence suggests that the most important mechanism may be damage caused by the body’s own inflammatory response and immune system.

Although this study looked at hospitalized cases, the team says that even those patients who are not sick enough to be admitted may also have telltale signs of mild deterioration.

In the UK, one study found that around one in seven people surveyed reported having symptoms that included cognitive difficulties 12 weeks after a positive COVID-19 test. The image is in the public domain

Professor Adam Hampshire of the Department of Brain Sciences at Imperial College London, the study’s lead author, said: “Around 40,000 people have undergone intensive care with COVID-19 in England alone and many more. “They have been very ill, but not hospitalized. This means that there are a lot of people who still have cognition problems many months later. We need to look urgently at what can be done to help these people.”

Professor Menon and Professor Ed Bullmore of the Cambridge Department of Psychiatry co-lead working groups as part of the COVID-19 Clinical Neuroscience Study (COVID-CNS) aimed at identifying biomarkers that are related to deficiencies neurological as a result of COVID-19. and the neuroimaging changes associated with them.

Financing: The research was funded by NIHR BioResource, NIHR Cambridge Biomedical Research Center and Addenbrooke’s Charitable Trust.

About this news on cognition, aging and research on COVID-19

Author: Craig Brierley
Source: Cambridge University
Contact: Craig Brierley – Cambridge University
Image: The image is in the public domain

Original research: Open Access.
“Multivariate profile and acute phase correlation of cognitive deficits in a cohort hospitalized for COVID-19” by Hampshire, A et al. Eclinical medicine


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Multivariate profile and acute phase correlation of cognitive deficits in a cohort hospitalized with COVID-19


Preliminary evidence has revealed a possible association between severe COVID-19 and persistent cognitive deficits. Further research is required to confirm this association, to determine whether cognitive deficits are related to the clinical features of the acute phase, or to the state of mental health at the point of assessment, and to quantify the rate of recovery.


46 people who received critical care for COVID-19 at Addenbrooke Hospital between March 10, 2020 and July 31, 2020 (16 with mechanical ventilation) underwent a detailed computerized cognitive assessment along with scales which measured anxiety, depression, and post-traumatic stress disorder under moderately supervised conditions. up to 6.0 (± 2.1) months after acute illness.

Patient and equated control (N = 460) performances were transformed into standard deviation from expected scores, taking into account age and demographic factors using N = 66,008 regulatory datasets. Compounds of global accuracy and response time (G_SScore and G_RT) were calculated. Linear modeling predicted composite scoring deficits based on acute severity, mental health status on assessment, and time since hospital admission.

The pattern of deficits between tasks was qualitatively compared with the normal age-related decrease and early-stage dementia.


COVID-19 survivors were less accurate (G_SScore = -0.53SDs) and slower (G_RT = + 0.89SDs) in their responses than expected compared to their matching controls. Acute illness, but not chronic mental health, significantly predicted cognitive deviation from expected scores (G_SScore)p= 0.0037) and G_RT (p = 0.0366)).

The most prominent task associations with COVID-19 were for greater cognition and processing speed, which was qualitatively different from the profiles of normal aging and dementia and of similar magnitude to the effects of aging between 50 and 70. years old. The tendency to reduce deficits over time since the disease (r∼ = 0.15) did not reach statistical significance.


Cognitive deficits after severe COVID-19 are more strongly related to the severity of acute disease, persist for a long time to the chronic phase, and slowly recover, if they do, with a characteristic profile that highlights cognitive functions. and higher processing speed.


This work was funded by the Cambridge Biomedical Research Center (BRC) of the National Institutes of Health Research (NIHR), the NIHR Cambridge Clinical Research Center (BRC-1215-20014), Addenbrooke’s Charities Trust and the NIHR COVID-19 BioResource RG9402. AH is funded by the Center for Research and Technology Care at the UK Dementia Research Institute and the Biomedical Research Center at Imperial College London. ETB and DKM are supported by the NIHR Senior Researcher Awards. JBR has the support of Wellcome Trust (220258) and Medical Research Council (SUAG / 051 G101400). VFJN is funded by The Health Foundation Clinician Scientist Fellowship. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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