Just before the pandemic, a research team from King’s College London, Imperial College London and Cambridge University ran a series of online tests for the general public. They did so as part of the BBC2’s Horizon Great British Intelligence Test, one of the largest intelligence experiments ever. In early 2020, the study team expanded the questionnaires to also collect information about the effect of SARS-CoV-2 infection on patients’ cognitive performance.
Of the 81,337 people who took part in the tests, 12,689 said they had Covid-19. 3,559 participants experienced respiratory symptoms but were allowed to recover at home, 192 were hospitalized and a quarter required mechanical ventilation.
The results showed that a relationship can be established between poor cognitive performance and the severity of respiratory symptoms experienced by him. But also not all areas of the mind have been affected by Covid-19. Some cognitive skills, such as emotional discrimination (eg, recognizing faces expressing the same emotions) and working memory (eg, remembering where a series of squares appeared on a screen) were avoided.
The greatest deficiencies were found in executive tasks that require patients to think (eg, determine if relationships between words are the same) and solve problems (eg, determine the number of movements needed to move from one location to another).
To understand the magnitude of the deficit, the authors compared the pattern of scores on the tests to cognitive changes that occur from other causes. Effects in those mechanically ventilated were comparable to the average cognitive decline seen over 10 years of aging and corresponded to a difference of seven IQ points. The researchers conducted a series of examinations to ensure that the cognitive deficits were not due to other variables.
According to Dr. Adam Hampshire, the study’s lead author, the findings confirm results from a growing group of studies showing important effects of Covid-19 on patients’ brains that need further investigation. Researchers also want to know why some cognitive functions are affected more than others. and whether reducing the severity of the disease can also reduce the severity of cognitive problems.
The study could not show whether the effects on cognition were long-term, as no participant had been ill for more than six months. This requires long-term follow-up of patients. Additionally, the researchers say it would be beneficial to combine brain imaging and cognitive tests with other information about mental health and daily functioning.
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