A significant drop in intelligence was detected in patients who recovered from the coronavirus, especially among those who had a severe case of the virus, a new study published in the United Kingdom found last week.
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Those who had previously contracted the virus scored lower on intelligence tests and cognitive assessments than those who were never infected, the study published on July 22 in The Lancet journal EClincalMedicine showed.
Before the coronavirus outbreak spread worldwide, Adam Hampshire, cognitive neuroscientist at Imperial College London began working with the BBC on a nationwide cognitive study to determine the general level of the UK’s intelligence.
By May, when the pandemic had forced countries worldwide to go into lockdown and close their borders, Hampshire and his team incorporated questions related to COVID-19 into the surveys to determine whether the disease would have any lasting effects on cognitive abilities.
“At the time of writing, we had collected comprehensive cognitive test and questionnaire data from a very large cross-section of the general public, predominantly within the UK, as part of the Great British Intelligence Test - a collaborative project with BBC2 Horizon,” the researchers said.
“During May, at the peak of the UK lockdown, we expanded the questionnaire to include questions pertaining to the impact of the pandemic, including suspected or confirmed COVID-19 illness, alongside details of symptom persistence and severity, relevant pre-existing medical conditions, and measures of depression, anxiety and post-traumatic stress,” they added.
The researchers looked at data from 81,337 individuals across the UK and adjusted for a variety of factors, including age, sex, education level, first language, and other variables.
They found that the more severe a COVID-19 infection was, the more likely the recovered person would have a greater drop in intelligence. The most significant deficits were found in tasks that evaluated reasoning, planning, and selective attention. Previous large-scale studies have shown COVID-19 patients suffer from “brain fog” long after they have recovered.
“When examining the entire population, the deficits were most pronounced for paradigms that tapped cognitive functions such as reasoning, problem solving, spatial planning and target detection whilst sparing tests of simpler functions such as working-memory span as well as emotional processing,” the researchers said.
“These results accord with reports of long-COVID, where ‘brain fog,’ trouble concentrating and difficulty finding the correct words are common.”
A drop in IQ was also significantly more notable in those who had been hospitalized and put on a ventilator, according to the study. The deficit was even greater than the deficits recorded in people who had previously suffered a stroke and reported learning disabilities.
“The scale of the observed deficit was not insubstantial; the 0.47 SD global composite score reduction for the hospitalized with ventilator sub-group was greater than the average 10-year decline in global performance between the ages of 20 to 70 within this dataset,” the researchers added.
“It was larger than the mean deficit of 480 people who indicated they had previously suffered a stroke (−0.24SDs) and the 998 who reported learning disabilities (−0.38SDs). For comparison, in a classic intelligence test, 0.47 SDs equates to a 7-point difference in IQ.”
The results show that there is a “worrying association between COVID-19 illness and a broad range of higher cognitive functions in the early chronic phase. More research is needed to determine how long these deficits last and their biological/psychological basis,” Hampshire wrote on Twitter.
7/7 Upshot. Their is a worrying association between Covid-19 illness and a broad range of higher cognitive functions in the early chronic phase. More research is needed to determine how long these deficits last and their biological/psychological basis.— Adam Hampshire (@HampshireHub) July 23, 2021
Clinical Researcher at University College London Christina Pagel said that disaster could unfold if the disease continues to spread uncontrollably.
“I worry that once again we are watching an unfolding disaster while waiting for unequivocal evidence. Unequivocal evidence on long term impacts will, by definition, take months or years. Maybe it never will – but so far, trajectory is towards more certain evidence not less,” Pagel wrote on Twitter.
“What if by the time there can be no doubt of long-term problems in many people who’ve had COVID, we’ve allowed millions more infections leaving hundreds of thousands more people affected.”
10. What if by the time there can be no doubt of long term problems in many people who've had covid, we've allowed millions more infections leaving hundreds of thousands more people affected.— Prof. Christina Pagel (@chrischirp) July 23, 2021
ONS estimated 634K people with long covid that impacts their life in June. pic.twitter.com/VfSJzNqZVv